Today's Message Index:
----------------------
1. 07:11 AM - Re: Battery Solenoid (Relay) (David J. Spencer)
2. 07:17 AM - Re: Battery Solenoid (Relay) (David J. Spencer)
3. 10:03 AM - Re: Battery Solenoid (Relay) (Martini Luc J.R.)
4. 04:49 PM - Re: Battery Solenoid (Relay) (David J. Spencer)
5. 07:36 PM - Re: Battery Solenoid (Relay) (Martini Luc J.R.)
6. 07:50 PM - Re: Battery Solenoid (Relay) (Martini Luc J.R.)
Message 1
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| Subject: | Re: Battery Solenoid (Relay) |
--> Avionics-List message posted by: "David J. Spencer" <djs@54Transmission.com>
Luc...
The resistance didn't change with a reverse in polarity... it rarely does.
My VOM has a 1 amp capability. When I set it to AC voltage and ran a check
with the +/- cables I got .245 volt flow in either direction.
You raise an interesting point about the two different types of grounds...
power and audio. Both are separated in the wiring harness, but connected to
the same center point ground. Should there be two center point grounds?
Everything is very clean as I just rebuilt the wiring harness. I have had
it out twice and rechecked for faulty wiring or shielding touching the
center wire and it checks out just fine.
With the DC power source hooked directly to the power cable (I come off the
power bus with one power cable to the audio panel, 2 NavComs, transponder,
ADF and intercom though another set of breakers) to the radio stack, the
only thing I eliminated was the battery and the associated wiring... all
other noise sources (motors, alternator, gyros, etc.) were always off. I
was getting the hum just off the battery power with no other motors,
solenoids, regulators, gyros or anything turned on even connected.
The + cable was the one with the crimp in it. The negative cable is only
about 18" long and connected to the frame.
I have not checked the grounding strap from the engine to the firewall
within the last two months, but will be checking that also along with the
starter cables, ammeter cables (which I found had some "burned spots" on
them which was hidden from view until you "unbundled" all the wiring) and
installing an AmeriKing DC filter and Alternator filter. I've always though
Last year I replaced all the antenna cables as I found them to be bundled
and taped to the + power cable. I also replaced all the comm antennae
(fiberglass and cracked) with stainless steel, which helped a lot. The
controlled field I fly out of has a "cone of static" which many complain
about, but the FAA and FCC can't seem to isolate or do anything about, but
rather claim it's everybody's radios... when you lift off, sometimes, the
static is so bad you have to turn off the radios...
I also replaced the alternator, voltage regulator and OV regulator plus all
the associated wiring as some Avionics moron had butt spliced the field wire
"INSIDE" the firewall cannon plug. The butt splice was broken and, of
course, the field wire was going to ground. After 3 avionics shops checked
my alternator I took it out myself and found 3 diodes were bad...
AeroElectric found that one more was bad when they replaced my alternator
with an upgraded version with larger bearings.
Yesterday as I pulled out the + battery power cable, I found all the lights,
strobe, electric fuel pump, and fuel sensors taped (relatively new looking
tape) to the + power cable. Needless to say, during it's 36 year existence,
maintenance has always been done in FAA certified shops and done with a very
high level of poor quality.
I honestly think this is a wiring problem relative to 36 y/o wire, but I
won't know until I get all the wiring replaced and according to Beech wiring
diagram specifications.
Thanks for you help and input...
David J. Spencer
Super3
djs@54Transmission.com
----- Original Message -----
From: "Martini Luc J.R." <martini@foxinternet.net>
Subject: Re: Avionics-List: Battery Solenoid (Relay)
> --> Avionics-List message posted by: "Martini Luc J.R."
<martini@foxinternet.net>
>
> What was the reverse polarity reading? I assume since you did not give a
> value for another range on the VOM, that it was a Digitial Type.
>
> Do you have a 1 amp Current meter? From the ohmic check, that's about the
> current you are drawing if this is a DC load. If not, hook a 100 ohm
> resistor in series with the + battery Cable and measure the voltage drop
> across the resistor.
>
> As far as Radio noise in general GOOD GROUNDS (very low ohmic contact) are
> EVERYTHING.
>
> However, there are frequently 2 ground levels, SIGNAL ground and POWER
> ground. Great care must be taken when assembling your avionics to keep
> these two seperate, and connect them only at a SINGLE POINT ground.
>
> It is not a bad idea to stick your head under the panel, and clean the
> single point avionics ground to make sure the spade lugs and washers are
> not oxidized (high ohmic contact)
>
> It does not surprise me that with EXTERNAL DC power, that you do NOT have
> radio hum. since your do NOT have a source of noise..
generator/alternator,
> motors, etc.
>
> You did not mention if it was the + or the - battery lead that had a crimp
> splice in it. If it was in the + lead. other than creating a voltage
> drop... which would be reflected to the voltage regulator, i.e. the
> generator/alternator would be putting out more voltage than it should
> because it senses a Battery slightly low voltage condition. If on the
> other hand it was on the - side. as far as the radios go, it would be
like
> putting a resistance between the - battery terminal and Chasis Ground.
This
> could conceiveably cause the noise floor to be raised...but not likely if
> yourGenrator/Alternator grouind is good... By the way... have to checked
> that to make sure you have a good & clean grounding strap from the engine
to
> the firewall ??
>
> Luc
>
>
> ssage -----
> From: "David J. Spencer" <djs@54Transmission.com>
> To: <avionics-list@matronics.com>
> Subject: Re: Avionics-List: Battery Solenoid (Relay)
>
>
> > --> Avionics-List message posted by: "David J. Spencer"
> <djs@54Transmission.com>
> >
> > Luc...
> >
> > There was approximately 11 ohms between the + & - with the correct
> polarity
> > hook up on the VOM.
> >
> > I took out the battery cable yesterday and found a split in the
insulation
> > about 3/8" long which had been taped over. The cable itself had been
> > "crimped" creating a bulge and part of the internal wiring was broken at
> > that point.
> >
> > As best I could tell this open area was not laying on the skin but ,
> rather,
> > pointing away from the skin as the cable lay on the belly of the plane.
> >
> > This is being corrected with new wiring and proper attachments.
> >
> > I hooked the radios up to a DC power source i.e. they are isolated from
> > anything (except the antenna)... and the hum went away.
> >
> > David J. Spencer
> > Super3
> > djs@54Transmission.com
> >
> > ----- Original Message -----
> > From: "Martini Luc J.R." <martini@foxinternet.net>
> > To: <avionics-list@matronics.com>
> > Subject: Re: Avionics-List: Battery Solenoid (Relay)
> >
> >
> > > --> Avionics-List message posted by: "Martini Luc J.R."
> > <martini@foxinternet.net>
> > >
> > > What resistance do you read between the battery cable and ground. Be
> sure
> > > to take the measurement with the leads swapped as well as standard
> > polarity,
> > > i.e. red lead to + and black to -.. If you are NOT using a digital
VOM,
> > > then also take values in both polarities in more than one RANGE on the
> VOM
> > > (active devices - diodes /transistors - are non-linear.. give you a
good
> > > clue if the value changes). You may have another noise suppression
diode
> > > somewhere, and/or an RC type (Band Pass) noise filter , with possibly
a
> > bad
> > > capacitor in it.
> > >
> > > Let me know what you get.
> > >
> > > Luc Martini
> > > ----- Original Message -----
> > > From: "David J. Spencer" <djs@54Transmission.com>
> > > To: <avionics-list@matronics.com>
> > > Subject: Avionics-List: Battery Solenoid (Relay)
> > >
> > >
> > > > --> Avionics-List message posted by: "David J. Spencer"
> > > <djs@54Transmission.com>
> > > >
> > > > Hi all...
> > > >
> > > > Has anyone ever replaced the battery relay on their Beech A23-24
Super
> > > III?
> > > >
> > > > My relay seems to work fine, but is 36 y/o and uses a Kipvolt
Voltage
> > > > suppressor (diode) to eliminate voltage spikes flushing through the
> > > system.
> > > >
> > > > I am replacing the battery, ground and starter cables with new
cable
> > (AC
> > > > grade #0 wire for the 40 amp system) and am wondering if anyone has
> put
> > > in
> > > > a
> > > > new Aircraft grade battery relay from an aircraft supply (Spruce)
> > source
> > > > battery relay in place of ours.
> > > >
> > > > I can currently remove the battery, diode and battery rely and get
> > > current
> > > > continuity (VOM) through the system from the positive cable to the
> > > > negative cable or any
> > > > ground... everything is off... i.e switches, breaker etc. This is
> what
> > > > some
> > > > people think is causing a "hum" in the radios. The "hum" is
present
> > with
> > > > the engine off and running the radios off a fully charged battery.
.
> > > > Additionally, using the AC voltage test setup on the VOM I can
detect
> > > > current flow between the positive cable and ground... any ground.
> > > >
> > > >
> > > > I'm using certer point grounding, but all the avionics manual
> articles
> > > > point
> > > > to RMI induced noise through the hull by poor shielding on the DC
> power
> > > > lines.
> > > >
> > > > Beech doesn't seem to have these parts anymore.
> > > >
> > > > All comments welcomed...
> > > >
> > > > David J. Spencer
> > > > Super3
> > > > djs@54Transmission.com
> > > >
> > > >
> > >
> > >
> >
> >
>
>
Message 2
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| Subject: | Re: Battery Solenoid (Relay) |
--> Avionics-List message posted by: "David J. Spencer" <djs@54Transmission.com>
Luc...
Another point.
I always thought it strange that on start-up with a well charged battery the
ammeter always showed a charge for about 30-45 seconds when I turn on the
alternator. At times, with everything, but the intercom off it would simply
cycle charge like I was turning something on/off at regular cycles.
This, as you point out, was probably due to the + cable being broken
indicating a low battery condition to the VR.
I checked the alternator wiring yesterday and it is just fine... no grounded
field wire and everything else is normal.
David
----- Original Message -----
From: "Martini Luc J.R." <martini@foxinternet.net>
Subject: Re: Avionics-List: Battery Solenoid (Relay)
> --> Avionics-List message posted by: "Martini Luc J.R."
<martini@foxinternet.net>
>
> What was the reverse polarity reading? I assume since you did not give a
> value for another range on the VOM, that it was a Digitial Type.
>
> Do you have a 1 amp Current meter? From the ohmic check, that's about the
> current you are drawing if this is a DC load. If not, hook a 100 ohm
> resistor in series with the + battery Cable and measure the voltage drop
> across the resistor.
>
> As far as Radio noise in general GOOD GROUNDS (very low ohmic contact) are
> EVERYTHING.
>
> However, there are frequently 2 ground levels, SIGNAL ground and POWER
> ground. Great care must be taken when assembling your avionics to keep
> these two seperate, and connect them only at a SINGLE POINT ground.
>
> It is not a bad idea to stick your head under the panel, and clean the
> single point avionics ground to make sure the spade lugs and washers are
> not oxidized (high ohmic contact)
>
> It does not surprise me that with EXTERNAL DC power, that you do NOT have
> radio hum. since your do NOT have a source of noise..
generator/alternator,
> motors, etc.
>
> You did not mention if it was the + or the - battery lead that had a crimp
> splice in it. If it was in the + lead. other than creating a voltage
> drop... which would be reflected to the voltage regulator, i.e. the
> generator/alternator would be putting out more voltage than it should
> because it senses a Battery slightly low voltage condition. If on the
> other hand it was on the - side. as far as the radios go, it would be
like
> putting a resistance between the - battery terminal and Chasis Ground.
This
> could conceiveably cause the noise floor to be raised...but not likely if
> yourGenrator/Alternator grouind is good... By the way... have to checked
> that to make sure you have a good & clean grounding strap from the engine
to
> the firewall ??
>
> Luc
>
>
> ssage -----
> From: "David J. Spencer" <djs@54Transmission.com>
> To: <avionics-list@matronics.com>
> Subject: Re: Avionics-List: Battery Solenoid (Relay)
>
>
> > --> Avionics-List message posted by: "David J. Spencer"
> <djs@54Transmission.com>
> >
> > Luc...
> >
> > There was approximately 11 ohms between the + & - with the correct
> polarity
> > hook up on the VOM.
> >
> > I took out the battery cable yesterday and found a split in the
insulation
> > about 3/8" long which had been taped over. The cable itself had been
> > "crimped" creating a bulge and part of the internal wiring was broken at
> > that point.
> >
> > As best I could tell this open area was not laying on the skin but ,
> rather,
> > pointing away from the skin as the cable lay on the belly of the plane.
> >
> > This is being corrected with new wiring and proper attachments.
> >
> > I hooked the radios up to a DC power source i.e. they are isolated from
> > anything (except the antenna)... and the hum went away.
> >
> > David J. Spencer
> > Super3
> > djs@54Transmission.com
> >
> > ----- Original Message -----
> > From: "Martini Luc J.R." <martini@foxinternet.net>
> > To: <avionics-list@matronics.com>
> > Subject: Re: Avionics-List: Battery Solenoid (Relay)
> >
> >
> > > --> Avionics-List message posted by: "Martini Luc J.R."
> > <martini@foxinternet.net>
> > >
> > > What resistance do you read between the battery cable and ground. Be
> sure
> > > to take the measurement with the leads swapped as well as standard
> > polarity,
> > > i.e. red lead to + and black to -.. If you are NOT using a digital
VOM,
> > > then also take values in both polarities in more than one RANGE on the
> VOM
> > > (active devices - diodes /transistors - are non-linear.. give you a
good
> > > clue if the value changes). You may have another noise suppression
diode
> > > somewhere, and/or an RC type (Band Pass) noise filter , with possibly
a
> > bad
> > > capacitor in it.
> > >
> > > Let me know what you get.
> > >
> > > Luc Martini
> > > ----- Original Message -----
> > > From: "David J. Spencer" <djs@54Transmission.com>
> > > To: <avionics-list@matronics.com>
> > > Subject: Avionics-List: Battery Solenoid (Relay)
> > >
> > >
> > > > --> Avionics-List message posted by: "David J. Spencer"
> > > <djs@54Transmission.com>
> > > >
> > > > Hi all...
> > > >
> > > > Has anyone ever replaced the battery relay on their Beech A23-24
Super
> > > III?
> > > >
> > > > My relay seems to work fine, but is 36 y/o and uses a Kipvolt
Voltage
> > > > suppressor (diode) to eliminate voltage spikes flushing through the
> > > system.
> > > >
> > > > I am replacing the battery, ground and starter cables with new
cable
> > (AC
> > > > grade #0 wire for the 40 amp system) and am wondering if anyone has
> put
> > > in
> > > > a
> > > > new Aircraft grade battery relay from an aircraft supply (Spruce)
> > source
> > > > battery relay in place of ours.
> > > >
> > > > I can currently remove the battery, diode and battery rely and get
> > > current
> > > > continuity (VOM) through the system from the positive cable to the
> > > > negative cable or any
> > > > ground... everything is off... i.e switches, breaker etc. This is
> what
> > > > some
> > > > people think is causing a "hum" in the radios. The "hum" is
present
> > with
> > > > the engine off and running the radios off a fully charged battery.
.
> > > > Additionally, using the AC voltage test setup on the VOM I can
detect
> > > > current flow between the positive cable and ground... any ground.
> > > >
> > > >
> > > > I'm using certer point grounding, but all the avionics manual
> articles
> > > > point
> > > > to RMI induced noise through the hull by poor shielding on the DC
> power
> > > > lines.
> > > >
> > > > Beech doesn't seem to have these parts anymore.
> > > >
> > > > All comments welcomed...
> > > >
> > > > David J. Spencer
> > > > Super3
> > > > djs@54Transmission.com
> > > >
> > > >
> > >
> > >
> >
> >
>
>
Message 3
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| Subject: | Re: Battery Solenoid (Relay) |
--> Avionics-List message posted by: "Martini Luc J.R." <martini@foxinternet.net>
Hello again
There can be a very considerable difference in resitance readings of a VOM
for forward v. reverse polarity if you have an "Active Device" in the
circuit... i.e. a Diode, or a Transistor. Looking from the battery, you
could be looking at several of these, (diodes or transistors) which are
used for noise suppression, voltage spike protection, even internally in a
voltage regulator, and on the BATTERY BUS CIRCUIT, i.e, not isolated by a
circuit breaker.
If there is No change as you indicated, that simply verifies that you likely
DO NOT have an Active Device in the Battery Bus Circuit, since Active
Devices are very NON LINEAR, i.e., the reading you get on a VOM is typically
MUCH higher in one polarity than the other.
If your VOM has a 1 amp direct reading capability, the way to proceed is to
disconnected the + lead from the battery. Set your VOM to DC CURRENT
(milliaps or amps) & to the 1 Amp RANGE. Then Connect the VOM in SERIES
with the battery, i.e., VOM - lead to battery cable (where the LOAD is), and
+ lead to the battery + lead (Current Source).
The reading you will get will be in either MILLIAMPS (ma) or AMPS (A)..
depending on your meter...if the scale is calibrated in (ma), move the
decimal place to the right 3 spaces (X 1000) for (amps)
If you are using your fully charged aircraft battery,. you should get 1.09
Amps showing on the meter.:
12 VDC/11 OHMS = 1.09 AMPS.
Note that if you use external power the voltage might be higher, up to 14
volts.. that might damage your VOM since that is 1.3 Amps.
You may have done this already according to your note, but you read the
VOLTS RANGE, rather than the AMPS RANGE on the dial. Since each meter is
different, I have no way of knowing what the .245 you referred to really is.
The nice thing about using a CURRENT METER is that you can leave it hooked
up and go disconnect various things that power goes to, i.e voltage
regulators, bulkhead connectors, circuit breakers, etc. and with a quick
check see if the current dropped to ZERO.... BINGO... your problem is in
THAT CIRCUIT.
As to your question about Avionics Signal and Power Grounds. NO, they MUST
be connected together at ONE and ONLY one place for noise immunity... also
helps with lighning protection. Signal ground is not the same as AUDIO
ground.
That is not to say that Avionics Shops do things right... as you have found
out.
There is one other thing I should tell you about. Audio Panels are an even
MORE complicated item. In Audio Panels, they may have as many as 2 MORE
types of Grounds. King (KMA-24) is famous for this. You have to Isolate the
AUDIO GROUNDS as well. and may have to isolate the Pilot and Co-pilot audio
from ANY OTHER audio ground, as well as isolation from CHASIS GROUND.
These suckers can be real bears, and the source of Noise PICKUP (from
external sources such as motors, sparks (like bad shielding on spark plug
wires) and even external to the aircraft.. industrial sources.
The Noise Zone you mention is intriguing. There are two ways of looking at
the problem.. 1) that there exists a NOISE SOURCE in that area, or 2), that
there exists a SHIELD from radiation.
I believe the first is what everybody has been focused on. However, the
second is just as likely if not more so. For example, if there is a
significant magnetic disturbance in the area, or a very large metalic
structure in the area, or a hill with a lot of iron content.. etc. etc.
these can shield the background RF Noise Level The Automatic Gain Control
(AGC) circuits in you radios, and/or audio panel, would compensate by
INCREASING the GAIN... that would result in audio STATIC...exactly like what
you get when listening to your AM radio in the car when you drive through a
tunnel.
I got the point you made that you had EVERYTHING disconnected except the
Battery and the Avionics DC bus and of course the radios that power them..
One thing you should also do, is turn of your Transponder. Also, if the
Antenna Coax for the Transponder and the DME (if you have one) are run
parallel with other wiring bundles, that can be a source of severe static.
I always use Double Shielded Coax for these devices... some Av Shops do
not... and if I have to cross a wire bundle, I do it at as close to 90
degrees as I can.(the Electric and Magnetic Fields no not couple to the
other cable when; you do that) Obviously it pays to keep these Coax leads
as short as possible (but must generally be no shorter than 3 feet (1/2 wave
length).
Another general practice to follow is good GROUND PLANES for the antennas.
What that means generally, is as much flat metal around the antenna as your
airplane and avionics can afford; keep radiating elements like DME and
Transponder seperated by 6' from each other.. as well as from very low
signal sources like LORAN, GPS...Keep the Comm antenna away from those as
well... and strangely enough, keep these well away and UP-STREAM
(airstream) from non-electrically conductive surfaces such as Plexiglass,
Fiberglass etc. (these create static electricity that can couple the
discharge via inonizatiotion of the airstream) Then, have a Good Low ohmic
contact for the antennas. That means cleaning away all paint where the
antenna mounts, and Alodining the area. and on the INSIDE of the airplane,
make sure that your have a good clean contact in like fashion for the
antenna mounting nuts/bolts.
I just received another e-mail from you... about the odd charging habits of
your airplane. Keep in mind, that a fully charged battery is 12 VDC.
However, your voltage regulator puts out between 13.5 and 14.00 volts
depending on the current draw, and the internal setting of you voltage
regulator. You would be surprised at the variation in "Idling Current" from
one Regulator to the next. So, it does NOT surprise me that even after
starting your engines with a full battery, that they do a little chargin for
a while. What DOES surprise me is the CYCLING you mentioned. That was
common in the old days of RELAY type voltage regulagtors, but NOT for Solid
state Alternator Regulators.
Do you have some sort of switching arangement for left/right engine
alternators?
Luc
----- Original Message -----
From: "David J. Spencer" <djs@54Transmission.com>
Subject: Re: Avionics-List: Battery Solenoid (Relay)
> --> Avionics-List message posted by: "David J. Spencer"
<djs@54Transmission.com>
>
> Luc...
>
> The resistance didn't change with a reverse in polarity... it rarely does.
>
> My VOM has a 1 amp capability. When I set it to AC voltage and ran a
check
> with the +/- cables I got .245 volt flow in either direction.
>
> You raise an interesting point about the two different types of grounds...
> power and audio. Both are separated in the wiring harness, but connected
to
> the same center point ground. Should there be two center point grounds?
>
> Everything is very clean as I just rebuilt the wiring harness. I have had
> it out twice and rechecked for faulty wiring or shielding touching the
> center wire and it checks out just fine.
>
> With the DC power source hooked directly to the power cable (I come off
the
> power bus with one power cable to the audio panel, 2 NavComs, transponder,
> ADF and intercom though another set of breakers) to the radio stack, the
> only thing I eliminated was the battery and the associated wiring... all
> other noise sources (motors, alternator, gyros, etc.) were always off. I
> was getting the hum just off the battery power with no other motors,
> solenoids, regulators, gyros or anything turned on even connected.
>
> The + cable was the one with the crimp in it. The negative cable is only
> about 18" long and connected to the frame.
>
> I have not checked the grounding strap from the engine to the firewall
> within the last two months, but will be checking that also along with the
> starter cables, ammeter cables (which I found had some "burned spots" on
> them which was hidden from view until you "unbundled" all the wiring) and
> installing an AmeriKing DC filter and Alternator filter. I've always
though
>
> Last year I replaced all the antenna cables as I found them to be bundled
> and taped to the + power cable. I also replaced all the comm antennae
> (fiberglass and cracked) with stainless steel, which helped a lot. The
> controlled field I fly out of has a "cone of static" which many complain
> about, but the FAA and FCC can't seem to isolate or do anything about, but
> rather claim it's everybody's radios... when you lift off, sometimes, the
> static is so bad you have to turn off the radios...
>
> I also replaced the alternator, voltage regulator and OV regulator plus
all
> the associated wiring as some Avionics moron had butt spliced the field
wire
> "INSIDE" the firewall cannon plug. The butt splice was broken and, of
> course, the field wire was going to ground. After 3 avionics shops
checked
> my alternator I took it out myself and found 3 diodes were bad...
> AeroElectric found that one more was bad when they replaced my alternator
> with an upgraded version with larger bearings.
>
> Yesterday as I pulled out the + battery power cable, I found all the
lights,
> strobe, electric fuel pump, and fuel sensors taped (relatively new looking
> tape) to the + power cable. Needless to say, during it's 36 year
existence,
> maintenance has always been done in FAA certified shops and done with a
very
> high level of poor quality.
>
> I honestly think this is a wiring problem relative to 36 y/o wire, but I
> won't know until I get all the wiring replaced and according to Beech
wiring
> diagram specifications.
>
> Thanks for you help and input...
>
> David J. Spencer
> Super3
> djs@54Transmission.com
>
>
> ----- Original Message -----
> From: "Martini Luc J.R." <martini@foxinternet.net>
> To: <avionics-list@matronics.com>
> Subject: Re: Avionics-List: Battery Solenoid (Relay)
>
>
> > --> Avionics-List message posted by: "Martini Luc J.R."
> <martini@foxinternet.net>
> >
> > What was the reverse polarity reading? I assume since you did not give
a
> > value for another range on the VOM, that it was a Digitial Type.
> >
> > Do you have a 1 amp Current meter? From the ohmic check, that's about
the
> > current you are drawing if this is a DC load. If not, hook a 100 ohm
> > resistor in series with the + battery Cable and measure the voltage
drop
> > across the resistor.
> >
> > As far as Radio noise in general GOOD GROUNDS (very low ohmic contact)
are
> > EVERYTHING.
> >
> > However, there are frequently 2 ground levels, SIGNAL ground and POWER
> > ground. Great care must be taken when assembling your avionics to keep
> > these two seperate, and connect them only at a SINGLE POINT ground.
> >
> > It is not a bad idea to stick your head under the panel, and clean the
> > single point avionics ground to make sure the spade lugs and washers
are
> > not oxidized (high ohmic contact)
> >
> > It does not surprise me that with EXTERNAL DC power, that you do NOT
have
> > radio hum. since your do NOT have a source of noise..
> generator/alternator,
> > motors, etc.
> >
> > You did not mention if it was the + or the - battery lead that had a
crimp
> > splice in it. If it was in the + lead. other than creating a voltage
> > drop... which would be reflected to the voltage regulator, i.e. the
> > generator/alternator would be putting out more voltage than it should
> > because it senses a Battery slightly low voltage condition. If on the
> > other hand it was on the - side. as far as the radios go, it would be
> like
> > putting a resistance between the - battery terminal and Chasis Ground.
> This
> > could conceiveably cause the noise floor to be raised...but not likely
if
> > yourGenrator/Alternator grouind is good... By the way... have to
checked
> > that to make sure you have a good & clean grounding strap from the
engine
> to
> > the firewall ??
> >
> > Luc
> >
> >
> > ssage -----
> > From: "David J. Spencer" <djs@54Transmission.com>
> > To: <avionics-list@matronics.com>
> > Subject: Re: Avionics-List: Battery Solenoid (Relay)
> >
> >
> > > --> Avionics-List message posted by: "David J. Spencer"
> > <djs@54Transmission.com>
> > >
> > > Luc...
> > >
> > > There was approximately 11 ohms between the + & - with the correct
> > polarity
> > > hook up on the VOM.
> > >
> > > I took out the battery cable yesterday and found a split in the
> insulation
> > > about 3/8" long which had been taped over. The cable itself had been
> > > "crimped" creating a bulge and part of the internal wiring was broken
at
> > > that point.
> > >
> > > As best I could tell this open area was not laying on the skin but ,
> > rather,
> > > pointing away from the skin as the cable lay on the belly of the
plane.
> > >
> > > This is being corrected with new wiring and proper attachments.
> > >
> > > I hooked the radios up to a DC power source i.e. they are isolated
from
> > > anything (except the antenna)... and the hum went away.
> > >
> > > David J. Spencer
> > > Super3
> > > djs@54Transmission.com
> > >
> > > ----- Original Message -----
> > > From: "Martini Luc J.R." <martini@foxinternet.net>
> > > To: <avionics-list@matronics.com>
> > > Subject: Re: Avionics-List: Battery Solenoid (Relay)
> > >
> > >
> > > > --> Avionics-List message posted by: "Martini Luc J.R."
> > > <martini@foxinternet.net>
> > > >
> > > > What resistance do you read between the battery cable and ground.
Be
> > sure
> > > > to take the measurement with the leads swapped as well as standard
> > > polarity,
> > > > i.e. red lead to + and black to -.. If you are NOT using a digital
> VOM,
> > > > then also take values in both polarities in more than one RANGE on
the
> > VOM
> > > > (active devices - diodes /transistors - are non-linear.. give you a
> good
> > > > clue if the value changes). You may have another noise suppression
> diode
> > > > somewhere, and/or an RC type (Band Pass) noise filter , with
possibly
> a
> > > bad
> > > > capacitor in it.
> > > >
> > > > Let me know what you get.
> > > >
> > > > Luc Martini
> > > > ----- Original Message -----
> > > > From: "David J. Spencer" <djs@54Transmission.com>
> > > > To: <avionics-list@matronics.com>
> > > > Subject: Avionics-List: Battery Solenoid (Relay)
> > > >
> > > >
> > > > > --> Avionics-List message posted by: "David J. Spencer"
> > > > <djs@54Transmission.com>
> > > > >
> > > > > Hi all...
> > > > >
> > > > > Has anyone ever replaced the battery relay on their Beech A23-24
> Super
> > > > III?
> > > > >
> > > > > My relay seems to work fine, but is 36 y/o and uses a Kipvolt
> Voltage
> > > > > suppressor (diode) to eliminate voltage spikes flushing through
the
> > > > system.
> > > > >
> > > > > I am replacing the battery, ground and starter cables with new
> cable
> > > (AC
> > > > > grade #0 wire for the 40 amp system) and am wondering if anyone
has
> > put
> > > > in
> > > > > a
> > > > > new Aircraft grade battery relay from an aircraft supply (Spruce)
> > > source
> > > > > battery relay in place of ours.
> > > > >
> > > > > I can currently remove the battery, diode and battery rely and
get
> > > > current
> > > > > continuity (VOM) through the system from the positive cable to
the
> > > > > negative cable or any
> > > > > ground... everything is off... i.e switches, breaker etc. This
is
> > what
> > > > > some
> > > > > people think is causing a "hum" in the radios. The "hum" is
> present
> > > with
> > > > > the engine off and running the radios off a fully charged
battery.
> .
> > > > > Additionally, using the AC voltage test setup on the VOM I can
> detect
> > > > > current flow between the positive cable and ground... any ground.
> > > > >
> > > > >
> > > > > I'm using certer point grounding, but all the avionics manual
> > articles
> > > > > point
> > > > > to RMI induced noise through the hull by poor shielding on the DC
> > power
> > > > > lines.
> > > > >
> > > > > Beech doesn't seem to have these parts anymore.
> > > > >
> > > > > All comments welcomed...
> > > > >
> > > > > David J. Spencer
> > > > > Super3
> > > > > djs@54Transmission.com
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >
> >
> >
>
>
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| Subject: | Re: Battery Solenoid (Relay) |
--> Avionics-List message posted by: "David J. Spencer" <djs@54Transmission.com>
Wow... what a wealth of information... You will never know how much this is
helping and I really appreciate your input.
First of all this is a single engine plane (1967 Beech Musketeer, 200 hp
Lycoming with fuel injection, A23-24 or Super III), so I only have one
alternator. Now to the cycling which I mentioned. The VR was a contact
type which I replaced with a Zeftronic unit. The cycling continued. I then
replaced the OV regulator with the matched Zeftronic solid state affair and
the cycling has stopped. I thought it might be one or the other as nothing
except the alternator and intercom were running when I last got fed up with
the noise.
Turn off the alternator and the noise went away. It just made sense and the
VR & OV were both original equipment and 36+ years old.
Thank you... You are correct for correcting me about resistance with or
without inline devices... I just wasn't thinking when I said there is no
difference as I always try to simplify the circuit to it's barest essentials
and then load on devices until I find a problem. Just my untrained
methodology.
I will run the amperage test when I get some new battery cable installed. I
bought #4 as it met the continuous usage requirements as per the chart on
page 1-10 of Robert G. Horan's "Avionics Installation Handbook"... HOWEVER,
the plane came with #0 wire and I am going to replace it with #0 wire. The
run from the battery to the starter solenoid is about 12 feet (12 volt
system) and then another 5 feet to the starter. The alternator is a 40 amp
unit, but my guess is that the amperage on engine start may be high enough
to warrant the heavier cable. Anyway what the hell it's just money and it
"might" prevent something I don't understand is going on... safe is better
than crispy.
Now to the audio panel. I have a Terra TMA 230 with a marker beacon and two
Terra TXN-960 NavComs with glide slopes and ILS which I call a radio stack.
I also have a KLN-88, cooling fan, King KT-76 transponder, Sigtronics
SPA-400 intercom and Collins RCR-650/IND 650 ADF. The audio panel has three
audio grounds (connected) and one chassis ground.
AND THANK YOU VERY MUCH -- YOU JUST JOGGED MY MEMORY-- THE GROUNDS FOR THE
ADF, TRANSPONDER & COOLING FAN ARE NOT ON THE CENTERPOINT SYSTEM. I also
have not put a ground on the radio trays themselves... I think I should.
Also, my centerpoint system is a terminal block where all the posts are
connected to the same frame point as the ground. This allowed me to create
a neat little area where all the grounds (except the ones I just mentioned)
are located. The intercom requires insulating all the headset jacks (with
isolation washers) and using the centerpoint ground.
Now to the Cone of Static... below is a diagram of the airport in
relationship to some 1600' AGL radio, TV & Microwave transmission towers
which are South of the field about 5 miles. The airport is directly between
the towers and Downtown Dallas Texas. Is it possible that the towers could
be transmitting a directional signal toward downtown?
++++
+++++ Radio Transmission towers (~15 @ 1600' AGL)
+++++
about
five miles to towers
|
|
| Runway (17/35)
|
|
about three miles
DOWNTOWN DALLAS TEXAS
As for large metallic structures...there are two hangars built by Howard
Hughes for something really big right on the 17/35 runway. Other than that
there is an FBI/U.S. Customs helicopter hangar (which tends to be rather a
secretive place) on the South end of the field and a medium sized strip mall
just across a highway to the South. There is also a six story Wells Fargo
Bank down by the FBI.
There is a National Guard Armory on the West side of the field which, I
believe has some radio antennae sticking up in the wooded area adjacent to
it... I'll check on the way home. My wife (she's a pilot also) says she
thinks the bank tower has dish antennae on it... either the bank or the FBI.
That's her side of the plane so I never look out there, because I don't want
to see what she's going to hit, and will check on it on way home.
The antennas are well grounded, but are on the aft slope of the top of the
fuselage (fuselage much like a V-35 Bonanza). After putting in the ADF
which required triaxial cable I changed EVERYTHING to triaxial as it just
seemed the logical thing to do.
They are too close together (about 2 feet apart), but are about 5 feet aft
of the Loran antenna. The transponder is under the foward fuselage (blade
type) and the ADF & marker beacon are on the bottom aft fuselage. The
aftmost comm antenna is very close to the vertical stabilizer which has an
ABS plastic shroud on the leading edge to affect airflow. I never thought
much about the static from plastic as all I've read indicates that our plane
is too slow... we cruise at ~145-150 mph with take-off and climb at 90-100
mph. Should I install some static wicks?
We only get this static garbage at this airport... no where else we have
flown has given us any problems and we have been into some strange places
like the Arizona & New Mexico desert and along the U.S./ Mexico border.
You will never know how much you are helping... I tend to be a rather
tenacious person and want very much to understand as much as possible about
what is going on and how to eliminate it... if possible.
David
----- Original Message -----
From: "Martini Luc J.R." <martini@foxinternet.net>
Subject: Re: Avionics-List: Battery Solenoid (Relay)
> --> Avionics-List message posted by: "Martini Luc J.R."
<martini@foxinternet.net>
>
> Hello again
>
> There can be a very considerable difference in resitance readings of a VOM
> for forward v. reverse polarity if you have an "Active Device" in the
> circuit... i.e. a Diode, or a Transistor. Looking from the battery, you
> could be looking at several of these, (diodes or transistors) which are
> used for noise suppression, voltage spike protection, even internally in
a
> voltage regulator, and on the BATTERY BUS CIRCUIT, i.e, not isolated by a
> circuit breaker.
>
> If there is No change as you indicated, that simply verifies that you
likely
> DO NOT have an Active Device in the Battery Bus Circuit, since Active
> Devices are very NON LINEAR, i.e., the reading you get on a VOM is
typically
> MUCH higher in one polarity than the other.
>
> If your VOM has a 1 amp direct reading capability, the way to proceed is
to
> disconnected the + lead from the battery. Set your VOM to DC CURRENT
> (milliaps or amps) & to the 1 Amp RANGE. Then Connect the VOM in SERIES
> with the battery, i.e., VOM - lead to battery cable (where the LOAD is),
and
> + lead to the battery + lead (Current Source).
>
> The reading you will get will be in either MILLIAMPS (ma) or AMPS (A)..
> depending on your meter...if the scale is calibrated in (ma), move the
> decimal place to the right 3 spaces (X 1000) for (amps)
>
> If you are using your fully charged aircraft battery,. you should get
1.09
> Amps showing on the meter.:
>
> 12 VDC/11 OHMS = 1.09 AMPS.
>
> Note that if you use external power the voltage might be higher, up to 14
> volts.. that might damage your VOM since that is 1.3 Amps.
>
> You may have done this already according to your note, but you read the
> VOLTS RANGE, rather than the AMPS RANGE on the dial. Since each meter is
> different, I have no way of knowing what the .245 you referred to really
is.
>
> The nice thing about using a CURRENT METER is that you can leave it hooked
> up and go disconnect various things that power goes to, i.e voltage
> regulators, bulkhead connectors, circuit breakers, etc. and with a quick
> check see if the current dropped to ZERO.... BINGO... your problem is in
> THAT CIRCUIT.
>
> As to your question about Avionics Signal and Power Grounds. NO, they
MUST
> be connected together at ONE and ONLY one place for noise immunity...
also
> helps with lighning protection. Signal ground is not the same as AUDIO
> ground.
>
> That is not to say that Avionics Shops do things right... as you have
found
> out.
>
> There is one other thing I should tell you about. Audio Panels are an
even
> MORE complicated item. In Audio Panels, they may have as many as 2 MORE
> types of Grounds. King (KMA-24) is famous for this. You have to Isolate
the
> AUDIO GROUNDS as well. and may have to isolate the Pilot and Co-pilot
audio
> from ANY OTHER audio ground, as well as isolation from CHASIS GROUND.
> These suckers can be real bears, and the source of Noise PICKUP (from
> external sources such as motors, sparks (like bad shielding on spark plug
> wires) and even external to the aircraft.. industrial sources.
>
> The Noise Zone you mention is intriguing. There are two ways of looking
at
> the problem.. 1) that there exists a NOISE SOURCE in that area, or 2),
that
> there exists a SHIELD from radiation.
>
> I believe the first is what everybody has been focused on. However, the
> second is just as likely if not more so. For example, if there is a
> significant magnetic disturbance in the area, or a very large metalic
> structure in the area, or a hill with a lot of iron content.. etc. etc.
> these can shield the background RF Noise Level The Automatic Gain
Control
> (AGC) circuits in you radios, and/or audio panel, would compensate by
> INCREASING the GAIN... that would result in audio STATIC...exactly like
what
> you get when listening to your AM radio in the car when you drive through
a
> tunnel.
>
> I got the point you made that you had EVERYTHING disconnected except the
> Battery and the Avionics DC bus and of course the radios that power them..
> One thing you should also do, is turn of your Transponder. Also, if the
> Antenna Coax for the Transponder and the DME (if you have one) are run
> parallel with other wiring bundles, that can be a source of severe static.
> I always use Double Shielded Coax for these devices... some Av Shops do
> not... and if I have to cross a wire bundle, I do it at as close to 90
> degrees as I can.(the Electric and Magnetic Fields no not couple to the
> other cable when; you do that) Obviously it pays to keep these Coax
leads
> as short as possible (but must generally be no shorter than 3 feet (1/2
wave
> length).
>
> Another general practice to follow is good GROUND PLANES for the antennas.
> What that means generally, is as much flat metal around the antenna as
your
> airplane and avionics can afford; keep radiating elements like DME and
> Transponder seperated by 6' from each other.. as well as from very low
> signal sources like LORAN, GPS...Keep the Comm antenna away from those as
> well... and strangely enough, keep these well away and UP-STREAM
> (airstream) from non-electrically conductive surfaces such as Plexiglass,
> Fiberglass etc. (these create static electricity that can couple the
> discharge via inonizatiotion of the airstream) Then, have a Good Low
ohmic
> contact for the antennas. That means cleaning away all paint where the
> antenna mounts, and Alodining the area. and on the INSIDE of the
airplane,
> make sure that your have a good clean contact in like fashion for the
> antenna mounting nuts/bolts.
>
> I just received another e-mail from you... about the odd charging habits
of
> your airplane. Keep in mind, that a fully charged battery is 12 VDC.
> However, your voltage regulator puts out between 13.5 and 14.00 volts
> depending on the current draw, and the internal setting of you voltage
> regulator. You would be surprised at the variation in "Idling Current"
from
> one Regulator to the next. So, it does NOT surprise me that even after
> starting your engines with a full battery, that they do a little chargin
for
> a while. What DOES surprise me is the CYCLING you mentioned. That was
> common in the old days of RELAY type voltage regulagtors, but NOT for
Solid
> state Alternator Regulators.
>
> Do you have some sort of switching arangement for left/right engine
> alternators?
>
> Luc
>
>
> ----- Original Message -----
> From: "David J. Spencer" <djs@54Transmission.com>
> To: <avionics-list@matronics.com>
> Subject: Re: Avionics-List: Battery Solenoid (Relay)
>
>
> > --> Avionics-List message posted by: "David J. Spencer"
> <djs@54Transmission.com>
> >
> > Luc...
> >
> > The resistance didn't change with a reverse in polarity... it rarely
does.
> >
> > My VOM has a 1 amp capability. When I set it to AC voltage and ran a
> check
> > with the +/- cables I got .245 volt flow in either direction.
> >
> > You raise an interesting point about the two different types of
grounds...
> > power and audio. Both are separated in the wiring harness, but
connected
> to
> > the same center point ground. Should there be two center point grounds?
> >
> > Everything is very clean as I just rebuilt the wiring harness. I have
had
> > it out twice and rechecked for faulty wiring or shielding touching the
> > center wire and it checks out just fine.
> >
> > With the DC power source hooked directly to the power cable (I come off
> the
> > power bus with one power cable to the audio panel, 2 NavComs,
transponder,
> > ADF and intercom though another set of breakers) to the radio stack, the
> > only thing I eliminated was the battery and the associated wiring... all
> > other noise sources (motors, alternator, gyros, etc.) were always off.
I
> > was getting the hum just off the battery power with no other motors,
> > solenoids, regulators, gyros or anything turned on even connected.
> >
> > The + cable was the one with the crimp in it. The negative cable is
only
> > about 18" long and connected to the frame.
> >
> > I have not checked the grounding strap from the engine to the firewall
> > within the last two months, but will be checking that also along with
the
> > starter cables, ammeter cables (which I found had some "burned spots" on
> > them which was hidden from view until you "unbundled" all the wiring)
and
> > installing an AmeriKing DC filter and Alternator filter. I've always
> though
> >
> > Last year I replaced all the antenna cables as I found them to be
bundled
> > and taped to the + power cable. I also replaced all the comm antennae
> > (fiberglass and cracked) with stainless steel, which helped a lot. The
> > controlled field I fly out of has a "cone of static" which many complain
> > about, but the FAA and FCC can't seem to isolate or do anything about,
but
> > rather claim it's everybody's radios... when you lift off, sometimes,
the
> > static is so bad you have to turn off the radios...
> >
> > I also replaced the alternator, voltage regulator and OV regulator plus
> all
> > the associated wiring as some Avionics moron had butt spliced the field
> wire
> > "INSIDE" the firewall cannon plug. The butt splice was broken and, of
> > course, the field wire was going to ground. After 3 avionics shops
> checked
> > my alternator I took it out myself and found 3 diodes were bad...
> > AeroElectric found that one more was bad when they replaced my
alternator
> > with an upgraded version with larger bearings.
> >
> > Yesterday as I pulled out the + battery power cable, I found all the
> lights,
> > strobe, electric fuel pump, and fuel sensors taped (relatively new
looking
> > tape) to the + power cable. Needless to say, during it's 36 year
> existence,
> > maintenance has always been done in FAA certified shops and done with a
> very
> > high level of poor quality.
> >
> > I honestly think this is a wiring problem relative to 36 y/o wire, but I
> > won't know until I get all the wiring replaced and according to Beech
> wiring
> > diagram specifications.
> >
> > Thanks for you help and input...
> >
> > David J. Spencer
> > Super3
> > djs@54Transmission.com
> >
> >
> > ----- Original Message -----
> > From: "Martini Luc J.R." <martini@foxinternet.net>
> > To: <avionics-list@matronics.com>
> > Subject: Re: Avionics-List: Battery Solenoid (Relay)
> >
> >
> > > --> Avionics-List message posted by: "Martini Luc J.R."
> > <martini@foxinternet.net>
> > >
> > > What was the reverse polarity reading? I assume since you did not
give
> a
> > > value for another range on the VOM, that it was a Digitial Type.
> > >
> > > Do you have a 1 amp Current meter? From the ohmic check, that's about
> the
> > > current you are drawing if this is a DC load. If not, hook a 100 ohm
> > > resistor in series with the + battery Cable and measure the voltage
> drop
> > > across the resistor.
> > >
> > > As far as Radio noise in general GOOD GROUNDS (very low ohmic contact)
> are
> > > EVERYTHING.
> > >
> > > However, there are frequently 2 ground levels, SIGNAL ground and POWER
> > > ground. Great care must be taken when assembling your avionics to
keep
> > > these two seperate, and connect them only at a SINGLE POINT ground.
> > >
> > > It is not a bad idea to stick your head under the panel, and clean the
> > > single point avionics ground to make sure the spade lugs and washers
> are
> > > not oxidized (high ohmic contact)
> > >
> > > It does not surprise me that with EXTERNAL DC power, that you do NOT
> have
> > > radio hum. since your do NOT have a source of noise..
> > generator/alternator,
> > > motors, etc.
> > >
> > > You did not mention if it was the + or the - battery lead that had a
> crimp
> > > splice in it. If it was in the + lead. other than creating a voltage
> > > drop... which would be reflected to the voltage regulator, i.e. the
> > > generator/alternator would be putting out more voltage than it should
> > > because it senses a Battery slightly low voltage condition. If on
the
> > > other hand it was on the - side. as far as the radios go, it would be
> > like
> > > putting a resistance between the - battery terminal and Chasis Ground.
> > This
> > > could conceiveably cause the noise floor to be raised...but not likely
> if
> > > yourGenrator/Alternator grouind is good... By the way... have to
> checked
> > > that to make sure you have a good & clean grounding strap from the
> engine
> > to
> > > the firewall ??
> > >
> > > Luc
> > >
> > >
> > > ssage -----
> > > From: "David J. Spencer" <djs@54Transmission.com>
> > > To: <avionics-list@matronics.com>
> > > Subject: Re: Avionics-List: Battery Solenoid (Relay)
> > >
> > >
> > > > --> Avionics-List message posted by: "David J. Spencer"
> > > <djs@54Transmission.com>
> > > >
> > > > Luc...
> > > >
> > > > There was approximately 11 ohms between the + & - with the correct
> > > polarity
> > > > hook up on the VOM.
> > > >
> > > > I took out the battery cable yesterday and found a split in the
> > insulation
> > > > about 3/8" long which had been taped over. The cable itself had
been
> > > > "crimped" creating a bulge and part of the internal wiring was
broken
> at
> > > > that point.
> > > >
> > > > As best I could tell this open area was not laying on the skin but ,
> > > rather,
> > > > pointing away from the skin as the cable lay on the belly of the
> plane.
> > > >
> > > > This is being corrected with new wiring and proper attachments.
> > > >
> > > > I hooked the radios up to a DC power source i.e. they are isolated
> from
> > > > anything (except the antenna)... and the hum went away.
> > > >
> > > > David J. Spencer
> > > > Super3
> > > > djs@54Transmission.com
> > > >
> > > > ----- Original Message -----
> > > > From: "Martini Luc J.R." <martini@foxinternet.net>
> > > > To: <avionics-list@matronics.com>
> > > > Subject: Re: Avionics-List: Battery Solenoid (Relay)
> > > >
> > > >
> > > > > --> Avionics-List message posted by: "Martini Luc J.R."
> > > > <martini@foxinternet.net>
> > > > >
> > > > > What resistance do you read between the battery cable and ground.
> Be
> > > sure
> > > > > to take the measurement with the leads swapped as well as standard
> > > > polarity,
> > > > > i.e. red lead to + and black to -.. If you are NOT using a
digital
> > VOM,
> > > > > then also take values in both polarities in more than one RANGE on
> the
> > > VOM
> > > > > (active devices - diodes /transistors - are non-linear.. give you
a
> > good
> > > > > clue if the value changes). You may have another noise suppression
> > diode
> > > > > somewhere, and/or an RC type (Band Pass) noise filter , with
> possibly
> > a
> > > > bad
> > > > > capacitor in it.
> > > > >
> > > > > Let me know what you get.
> > > > >
> > > > > Luc Martini
> > > > > ----- Original Message -----
> > > > > From: "David J. Spencer" <djs@54Transmission.com>
> > > > > To: <avionics-list@matronics.com>
> > > > > Subject: Avionics-List: Battery Solenoid (Relay)
> > > > >
> > > > >
> > > > > > --> Avionics-List message posted by: "David J. Spencer"
> > > > > <djs@54Transmission.com>
> > > > > >
> > > > > > Hi all...
> > > > > >
> > > > > > Has anyone ever replaced the battery relay on their Beech A23-24
> > Super
> > > > > III?
> > > > > >
> > > > > > My relay seems to work fine, but is 36 y/o and uses a Kipvolt
> > Voltage
> > > > > > suppressor (diode) to eliminate voltage spikes flushing through
> the
> > > > > system.
> > > > > >
> > > > > > I am replacing the battery, ground and starter cables with new
> > cable
> > > > (AC
> > > > > > grade #0 wire for the 40 amp system) and am wondering if anyone
> has
> > > put
> > > > > in
> > > > > > a
> > > > > > new Aircraft grade battery relay from an aircraft supply
(Spruce)
> > > > source
> > > > > > battery relay in place of ours.
> > > > > >
> > > > > > I can currently remove the battery, diode and battery rely and
> get
> > > > > current
> > > > > > continuity (VOM) through the system from the positive cable to
> the
> > > > > > negative cable or any
> > > > > > ground... everything is off... i.e switches, breaker etc. This
> is
> > > what
> > > > > > some
> > > > > > people think is causing a "hum" in the radios. The "hum" is
> > present
> > > > with
> > > > > > the engine off and running the radios off a fully charged
> battery.
> > .
> > > > > > Additionally, using the AC voltage test setup on the VOM I can
> > detect
> > > > > > current flow between the positive cable and ground... any
ground.
> > > > > >
> > > > > >
> > > > > > I'm using certer point grounding, but all the avionics manual
> > > articles
> > > > > > point
> > > > > > to RMI induced noise through the hull by poor shielding on the
DC
> > > power
> > > > > > lines.
> > > > > >
> > > > > > Beech doesn't seem to have these parts anymore.
> > > > > >
> > > > > > All comments welcomed...
> > > > > >
> > > > > > David J. Spencer
> > > > > > Super3
> > > > > > djs@54Transmission.com
> > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >
> >
> >
>
>
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| Subject: | Re: Battery Solenoid (Relay) |
--> Avionics-List message posted by: "Martini Luc J.R." <martini@foxinternet.net>
Glad to help out.
I forgot to ask if there is a significant Magnetic Deviation in that area
(what do they show on the maps?).. that would indicate an iron concentration
in the ground that could be acting as an RF shield. The effective range of
signals like VOR would also be decreased in such an area.
As for Static wicks.. they never hurt, but are not all that cheap. Static
discharge is more a function of humidity (altitude) than airspeed. There
are 2
advantages to Static wicks in addition to possibly reducing radio noise !)
is reduces galvanic corrosion..2) if you get hit by lightning, the tuffs
disappear instead of a piece of your flight control surfaces.
A lot of people don't realize that a plasma is not just a current, but
actually moves mater. The example I like to point out are the points in an
old distributor... No doubt you have noticed, that one side it builds a
mountain, and the other side a pit. The mountain and the pit are always on
the same side of the points. Current flows from - to +. when you open the
points a plasma arc forms. The flow of electrons (which are pretty light
but there are a lot of them and traveling at near the speed of
light. However, at the moment you open the circuit, the total energy in the
system must be equal, and you just stopped E=MC squared going that away
(toward the possitive terminal) instantaneously, For things to equal out,
metal (mass) must flow in the opposite direction to equalize energy state
equation. Electrons are light, so it does not take many atoms of
metal going much slower in the opposite direction for things to equal out,
quenching the plasma. The result however is that the metal builds up over
time on the - side of the points.. and that metal obviously comes from the
+ side.
So, if your airplane is hit with lightning, the tuffs will vaporize... In
military airplanes, they also provide bonding straps between the fuselage
and the flight control surfaces, so that no arcing occurs in the bearing/
bolts/pins that hold them on.
For the radios, you might be surprised how much you gain is Effective Range
for your receivers.. you find you pick up VOR stations for example quite a
few miles further out than before you spent your money and time on reducing
noise sources.
I take it that other people have bitched about the noise problem in your
local area.
With the advent of Cellphones, the general noise level have increased
dramatically. That is because cellphones are a SWITCHED System. When ever
you switch something on and off , you create noise. Take again for example,
the old car distributor with points. If you create a PLASMA, you are
radiating Radio Frequencies (Usually AM) , and as everyone knows, you
splatter AM noise
content all over the dial . If you SWITCH an RF signal on and off, the
amount of Noise content you generate is directly proportional to the Rise
and Fall time of the pulse. The faster the switch things on and off, the
worse it gets. A Zero Rise and Fall time,,, which is of course impossible,
would splatter equal amplitude from DC to Infinity. (and such noise could
also be FM -harmonic content) So, in short,
cellphones suck for radio... They have been the bane of Broadcast TV for
example..
And, as you might have expected, if the Ambient Noise Level goes UP, your
radio AGC compensates by turning the Signal Gain DOWN to compensate... Not
nice!
Do you by chance know any Ham Radio Operators in your area??? Those guys
would be your best bet for finding the Noise SOURCE in the neighborhood.
There is an instrument called a Field Strength Meter, which is nothing more
than a Directional Antenna hooked to a TUNED Circuit, hooked up to an AM
detector (diode) and that in turn to a sensitive meter movement. In short,
a radio of sorts. They can go around and see where the strongest signals
are coming from, and use their ham gear to see if the noise is strictly AM
or possibly FM as well, and how much bandwidth is affected. THEN you can go
to the guys causing the problem and threaten them with legal action if they
don't clean up their act and/or go to the FAA and FCC with evidence in hand
and bitch.
Luc
----- Original Message -----
From: "David J. Spencer" <djs@54Transmission.com>
Subject: Re: Avionics-List: Battery Solenoid (Relay)
> --> Avionics-List message posted by: "David J. Spencer"
<djs@54Transmission.com>
>
> Wow... what a wealth of information... You will never know how much this
is
> helping and I really appreciate your input.
>
> First of all this is a single engine plane (1967 Beech Musketeer, 200 hp
> Lycoming with fuel injection, A23-24 or Super III), so I only have one
> alternator. Now to the cycling which I mentioned. The VR was a contact
> type which I replaced with a Zeftronic unit. The cycling continued. I
then
> replaced the OV regulator with the matched Zeftronic solid state affair
and
> the cycling has stopped. I thought it might be one or the other as
nothing
> except the alternator and intercom were running when I last got fed up
with
> the noise.
>
> Turn off the alternator and the noise went away. It just made sense and
the
> VR & OV were both original equipment and 36+ years old.
>
> Thank you... You are correct for correcting me about resistance with or
> without inline devices... I just wasn't thinking when I said there is no
> difference as I always try to simplify the circuit to it's barest
essentials
> and then load on devices until I find a problem. Just my untrained
> methodology.
>
> I will run the amperage test when I get some new battery cable installed.
I
> bought #4 as it met the continuous usage requirements as per the chart on
> page 1-10 of Robert G. Horan's "Avionics Installation Handbook"...
HOWEVER,
> the plane came with #0 wire and I am going to replace it with #0 wire.
The
> run from the battery to the starter solenoid is about 12 feet (12 volt
> system) and then another 5 feet to the starter. The alternator is a 40
amp
> unit, but my guess is that the amperage on engine start may be high enough
> to warrant the heavier cable. Anyway what the hell it's just money and it
> "might" prevent something I don't understand is going on... safe is better
> than crispy.
>
> Now to the audio panel. I have a Terra TMA 230 with a marker beacon and
two
> Terra TXN-960 NavComs with glide slopes and ILS which I call a radio
stack.
> I also have a KLN-88, cooling fan, King KT-76 transponder, Sigtronics
> SPA-400 intercom and Collins RCR-650/IND 650 ADF. The audio panel has
three
> audio grounds (connected) and one chassis ground.
>
> AND THANK YOU VERY MUCH -- YOU JUST JOGGED MY MEMORY-- THE GROUNDS FOR
THE
> ADF, TRANSPONDER & COOLING FAN ARE NOT ON THE CENTERPOINT SYSTEM. I also
> have not put a ground on the radio trays themselves... I think I should.
>
> Also, my centerpoint system is a terminal block where all the posts are
> connected to the same frame point as the ground. This allowed me to
create
> a neat little area where all the grounds (except the ones I just
mentioned)
> are located. The intercom requires insulating all the headset jacks (with
> isolation washers) and using the centerpoint ground.
>
> Now to the Cone of Static... below is a diagram of the airport in
> relationship to some 1600' AGL radio, TV & Microwave transmission towers
> which are South of the field about 5 miles. The airport is directly
between
> the towers and Downtown Dallas Texas. Is it possible that the towers
could
> be transmitting a directional signal toward downtown?
>
>
> ++++
>
> +++++ Radio Transmission towers (~15 @ 1600' AGL)
>
> +++++
>
>
about
> five miles to towers
>
>
> |
> |
> | Runway
(17/35)
> |
> |
>
>
> about three miles
>
> DOWNTOWN DALLAS TEXAS
>
> As for large metallic structures...there are two hangars built by Howard
> Hughes for something really big right on the 17/35 runway. Other than
that
> there is an FBI/U.S. Customs helicopter hangar (which tends to be rather a
> secretive place) on the South end of the field and a medium sized strip
mall
> just across a highway to the South. There is also a six story Wells Fargo
> Bank down by the FBI.
>
> There is a National Guard Armory on the West side of the field which, I
> believe has some radio antennae sticking up in the wooded area adjacent to
> it... I'll check on the way home. My wife (she's a pilot also) says she
> thinks the bank tower has dish antennae on it... either the bank or the
FBI.
> That's her side of the plane so I never look out there, because I don't
want
> to see what she's going to hit, and will check on it on way home.
>
> The antennas are well grounded, but are on the aft slope of the top of the
> fuselage (fuselage much like a V-35 Bonanza). After putting in the ADF
> which required triaxial cable I changed EVERYTHING to triaxial as it just
> seemed the logical thing to do.
>
> They are too close together (about 2 feet apart), but are about 5 feet aft
> of the Loran antenna. The transponder is under the foward fuselage (blade
> type) and the ADF & marker beacon are on the bottom aft fuselage. The
> aftmost comm antenna is very close to the vertical stabilizer which has an
> ABS plastic shroud on the leading edge to affect airflow. I never thought
> much about the static from plastic as all I've read indicates that our
plane
> is too slow... we cruise at ~145-150 mph with take-off and climb at 90-100
> mph. Should I install some static wicks?
>
> We only get this static garbage at this airport... no where else we have
> flown has given us any problems and we have been into some strange places
> like the Arizona & New Mexico desert and along the U.S./ Mexico border.
>
> You will never know how much you are helping... I tend to be a rather
> tenacious person and want very much to understand as much as possible
about
> what is going on and how to eliminate it... if possible.
>
> David
>
>
> ----- Original Message -----
> From: "Martini Luc J.R." <martini@foxinternet.net>
> To: <avionics-list@matronics.com>
> Subject: Re: Avionics-List: Battery Solenoid (Relay)
>
>
> > --> Avionics-List message posted by: "Martini Luc J.R."
> <martini@foxinternet.net>
> >
> > Hello again
> >
> > There can be a very considerable difference in resitance readings of a
VOM
> > for forward v. reverse polarity if you have an "Active Device" in the
> > circuit... i.e. a Diode, or a Transistor. Looking from the battery,
you
> > could be looking at several of these, (diodes or transistors) which are
> > used for noise suppression, voltage spike protection, even internally
in
> a
> > voltage regulator, and on the BATTERY BUS CIRCUIT, i.e, not isolated by
a
> > circuit breaker.
> >
> > If there is No change as you indicated, that simply verifies that you
> likely
> > DO NOT have an Active Device in the Battery Bus Circuit, since Active
> > Devices are very NON LINEAR, i.e., the reading you get on a VOM is
> typically
> > MUCH higher in one polarity than the other.
> >
> > If your VOM has a 1 amp direct reading capability, the way to proceed
is
> to
> > disconnected the + lead from the battery. Set your VOM to DC CURRENT
> > (milliaps or amps) & to the 1 Amp RANGE. Then Connect the VOM in SERIES
> > with the battery, i.e., VOM - lead to battery cable (where the LOAD is),
> and
> > + lead to the battery + lead (Current Source).
> >
> > The reading you will get will be in either MILLIAMPS (ma) or AMPS (A)..
> > depending on your meter...if the scale is calibrated in (ma), move the
> > decimal place to the right 3 spaces (X 1000) for (amps)
> >
> > If you are using your fully charged aircraft battery,. you should get
> 1.09
> > Amps showing on the meter.:
> >
> > 12 VDC/11 OHMS = 1.09 AMPS.
> >
> > Note that if you use external power the voltage might be higher, up to
14
> > volts.. that might damage your VOM since that is 1.3 Amps.
> >
> > You may have done this already according to your note, but you read the
> > VOLTS RANGE, rather than the AMPS RANGE on the dial. Since each meter
is
> > different, I have no way of knowing what the .245 you referred to really
> is.
> >
> > The nice thing about using a CURRENT METER is that you can leave it
hooked
> > up and go disconnect various things that power goes to, i.e voltage
> > regulators, bulkhead connectors, circuit breakers, etc. and with a quick
> > check see if the current dropped to ZERO.... BINGO... your problem is in
> > THAT CIRCUIT.
> >
> > As to your question about Avionics Signal and Power Grounds. NO, they
> MUST
> > be connected together at ONE and ONLY one place for noise immunity...
> also
> > helps with lighning protection. Signal ground is not the same as AUDIO
> > ground.
> >
> > That is not to say that Avionics Shops do things right... as you have
> found
> > out.
> >
> > There is one other thing I should tell you about. Audio Panels are an
> even
> > MORE complicated item. In Audio Panels, they may have as many as 2 MORE
> > types of Grounds. King (KMA-24) is famous for this. You have to Isolate
> the
> > AUDIO GROUNDS as well. and may have to isolate the Pilot and Co-pilot
> audio
> > from ANY OTHER audio ground, as well as isolation from CHASIS GROUND.
> > These suckers can be real bears, and the source of Noise PICKUP (from
> > external sources such as motors, sparks (like bad shielding on spark
plug
> > wires) and even external to the aircraft.. industrial sources.
> >
> > The Noise Zone you mention is intriguing. There are two ways of looking
> at
> > the problem.. 1) that there exists a NOISE SOURCE in that area, or 2),
> that
> > there exists a SHIELD from radiation.
> >
> > I believe the first is what everybody has been focused on. However, the
> > second is just as likely if not more so. For example, if there is a
> > significant magnetic disturbance in the area, or a very large metalic
> > structure in the area, or a hill with a lot of iron content.. etc. etc.
> > these can shield the background RF Noise Level The Automatic Gain
> Control
> > (AGC) circuits in you radios, and/or audio panel, would compensate by
> > INCREASING the GAIN... that would result in audio STATIC...exactly like
> what
> > you get when listening to your AM radio in the car when you drive
through
> a
> > tunnel.
> >
> > I got the point you made that you had EVERYTHING disconnected except
the
> > Battery and the Avionics DC bus and of course the radios that power
them..
> > One thing you should also do, is turn of your Transponder. Also, if the
> > Antenna Coax for the Transponder and the DME (if you have one) are run
> > parallel with other wiring bundles, that can be a source of severe
static.
> > I always use Double Shielded Coax for these devices... some Av Shops do
> > not... and if I have to cross a wire bundle, I do it at as close to 90
> > degrees as I can.(the Electric and Magnetic Fields no not couple to the
> > other cable when; you do that) Obviously it pays to keep these Coax
> leads
> > as short as possible (but must generally be no shorter than 3 feet (1/2
> wave
> > length).
> >
> > Another general practice to follow is good GROUND PLANES for the
antennas.
> > What that means generally, is as much flat metal around the antenna as
> your
> > airplane and avionics can afford; keep radiating elements like DME and
> > Transponder seperated by 6' from each other.. as well as from very low
> > signal sources like LORAN, GPS...Keep the Comm antenna away from those
as
> > well... and strangely enough, keep these well away and UP-STREAM
> > (airstream) from non-electrically conductive surfaces such as
Plexiglass,
> > Fiberglass etc. (these create static electricity that can couple the
> > discharge via inonizatiotion of the airstream) Then, have a Good Low
> ohmic
> > contact for the antennas. That means cleaning away all paint where the
> > antenna mounts, and Alodining the area. and on the INSIDE of the
> airplane,
> > make sure that your have a good clean contact in like fashion for the
> > antenna mounting nuts/bolts.
> >
> > I just received another e-mail from you... about the odd charging habits
> of
> > your airplane. Keep in mind, that a fully charged battery is 12 VDC.
> > However, your voltage regulator puts out between 13.5 and 14.00 volts
> > depending on the current draw, and the internal setting of you voltage
> > regulator. You would be surprised at the variation in "Idling Current"
> from
> > one Regulator to the next. So, it does NOT surprise me that even after
> > starting your engines with a full battery, that they do a little chargin
> for
> > a while. What DOES surprise me is the CYCLING you mentioned. That was
> > common in the old days of RELAY type voltage regulagtors, but NOT for
> Solid
> > state Alternator Regulators.
> >
> > Do you have some sort of switching arangement for left/right engine
> > alternators?
> >
> > Luc
> >
> >
> > ----- Original Message -----
> > From: "David J. Spencer" <djs@54Transmission.com>
> > To: <avionics-list@matronics.com>
> > Subject: Re: Avionics-List: Battery Solenoid (Relay)
> >
> >
> > > --> Avionics-List message posted by: "David J. Spencer"
> > <djs@54Transmission.com>
> > >
> > > Luc...
> > >
> > > The resistance didn't change with a reverse in polarity... it rarely
> does.
> > >
> > > My VOM has a 1 amp capability. When I set it to AC voltage and ran a
> > check
> > > with the +/- cables I got .245 volt flow in either direction.
> > >
> > > You raise an interesting point about the two different types of
> grounds...
> > > power and audio. Both are separated in the wiring harness, but
> connected
> > to
> > > the same center point ground. Should there be two center point
grounds?
> > >
> > > Everything is very clean as I just rebuilt the wiring harness. I have
> had
> > > it out twice and rechecked for faulty wiring or shielding touching the
> > > center wire and it checks out just fine.
> > >
> > > With the DC power source hooked directly to the power cable (I come
off
> > the
> > > power bus with one power cable to the audio panel, 2 NavComs,
> transponder,
> > > ADF and intercom though another set of breakers) to the radio stack,
the
> > > only thing I eliminated was the battery and the associated wiring...
all
> > > other noise sources (motors, alternator, gyros, etc.) were always off.
> I
> > > was getting the hum just off the battery power with no other motors,
> > > solenoids, regulators, gyros or anything turned on even connected.
> > >
> > > The + cable was the one with the crimp in it. The negative cable is
> only
> > > about 18" long and connected to the frame.
> > >
> > > I have not checked the grounding strap from the engine to the firewall
> > > within the last two months, but will be checking that also along with
> the
> > > starter cables, ammeter cables (which I found had some "burned spots"
on
> > > them which was hidden from view until you "unbundled" all the wiring)
> and
> > > installing an AmeriKing DC filter and Alternator filter. I've always
> > though
> > >
> > > Last year I replaced all the antenna cables as I found them to be
> bundled
> > > and taped to the + power cable. I also replaced all the comm antennae
> > > (fiberglass and cracked) with stainless steel, which helped a lot.
The
> > > controlled field I fly out of has a "cone of static" which many
complain
> > > about, but the FAA and FCC can't seem to isolate or do anything about,
> but
> > > rather claim it's everybody's radios... when you lift off, sometimes,
> the
> > > static is so bad you have to turn off the radios...
> > >
> > > I also replaced the alternator, voltage regulator and OV regulator
plus
> > all
> > > the associated wiring as some Avionics moron had butt spliced the
field
> > wire
> > > "INSIDE" the firewall cannon plug. The butt splice was broken and, of
> > > course, the field wire was going to ground. After 3 avionics shops
> > checked
> > > my alternator I took it out myself and found 3 diodes were bad...
> > > AeroElectric found that one more was bad when they replaced my
> alternator
> > > with an upgraded version with larger bearings.
> > >
> > > Yesterday as I pulled out the + battery power cable, I found all the
> > lights,
> > > strobe, electric fuel pump, and fuel sensors taped (relatively new
> looking
> > > tape) to the + power cable. Needless to say, during it's 36 year
> > existence,
> > > maintenance has always been done in FAA certified shops and done with
a
> > very
> > > high level of poor quality.
> > >
> > > I honestly think this is a wiring problem relative to 36 y/o wire, but
I
> > > won't know until I get all the wiring replaced and according to Beech
> > wiring
> > > diagram specifications.
> > >
> > > Thanks for you help and input...
> > >
> > > David J. Spencer
> > > Super3
> > > djs@54Transmission.com
> > >
> > >
> > > ----- Original Message -----
> > > From: "Martini Luc J.R." <martini@foxinternet.net>
> > > To: <avionics-list@matronics.com>
> > > Subject: Re: Avionics-List: Battery Solenoid (Relay)
> > >
> > >
> > > > --> Avionics-List message posted by: "Martini Luc J.R."
> > > <martini@foxinternet.net>
> > > >
> > > > What was the reverse polarity reading? I assume since you did not
> give
> > a
> > > > value for another range on the VOM, that it was a Digitial Type.
> > > >
> > > > Do you have a 1 amp Current meter? From the ohmic check, that's
about
> > the
> > > > current you are drawing if this is a DC load. If not, hook a 100
ohm
> > > > resistor in series with the + battery Cable and measure the voltage
> > drop
> > > > across the resistor.
> > > >
> > > > As far as Radio noise in general GOOD GROUNDS (very low ohmic
contact)
> > are
> > > > EVERYTHING.
> > > >
> > > > However, there are frequently 2 ground levels, SIGNAL ground and
POWER
> > > > ground. Great care must be taken when assembling your avionics to
> keep
> > > > these two seperate, and connect them only at a SINGLE POINT ground.
> > > >
> > > > It is not a bad idea to stick your head under the panel, and clean
the
> > > > single point avionics ground to make sure the spade lugs and washers
> > are
> > > > not oxidized (high ohmic contact)
> > > >
> > > > It does not surprise me that with EXTERNAL DC power, that you do
NOT
> > have
> > > > radio hum. since your do NOT have a source of noise..
> > > generator/alternator,
> > > > motors, etc.
> > > >
> > > > You did not mention if it was the + or the - battery lead that had a
> > crimp
> > > > splice in it. If it was in the + lead. other than creating a
voltage
> > > > drop... which would be reflected to the voltage regulator, i.e. the
> > > > generator/alternator would be putting out more voltage than it
should
> > > > because it senses a Battery slightly low voltage condition. If on
> the
> > > > other hand it was on the - side. as far as the radios go, it would
be
> > > like
> > > > putting a resistance between the - battery terminal and Chasis
Ground.
> > > This
> > > > could conceiveably cause the noise floor to be raised...but not
likely
> > if
> > > > yourGenrator/Alternator grouind is good... By the way... have to
> > checked
> > > > that to make sure you have a good & clean grounding strap from the
> > engine
> > > to
> > > > the firewall ??
> > > >
> > > > Luc
> > > >
> > > >
> > > > ssage -----
> > > > From: "David J. Spencer" <djs@54Transmission.com>
> > > > To: <avionics-list@matronics.com>
> > > > Subject: Re: Avionics-List: Battery Solenoid (Relay)
> > > >
> > > >
> > > > > --> Avionics-List message posted by: "David J. Spencer"
> > > > <djs@54Transmission.com>
> > > > >
> > > > > Luc...
> > > > >
> > > > > There was approximately 11 ohms between the + & - with the correct
> > > > polarity
> > > > > hook up on the VOM.
> > > > >
> > > > > I took out the battery cable yesterday and found a split in the
> > > insulation
> > > > > about 3/8" long which had been taped over. The cable itself had
> been
> > > > > "crimped" creating a bulge and part of the internal wiring was
> broken
> > at
> > > > > that point.
> > > > >
> > > > > As best I could tell this open area was not laying on the skin but
,
> > > > rather,
> > > > > pointing away from the skin as the cable lay on the belly of the
> > plane.
> > > > >
> > > > > This is being corrected with new wiring and proper attachments.
> > > > >
> > > > > I hooked the radios up to a DC power source i.e. they are isolated
> > from
> > > > > anything (except the antenna)... and the hum went away.
> > > > >
> > > > > David J. Spencer
> > > > > Super3
> > > > > djs@54Transmission.com
> > > > >
> > > > > ----- Original Message -----
> > > > > From: "Martini Luc J.R." <martini@foxinternet.net>
> > > > > To: <avionics-list@matronics.com>
> > > > > Subject: Re: Avionics-List: Battery Solenoid (Relay)
> > > > >
> > > > >
> > > > > > --> Avionics-List message posted by: "Martini Luc J.R."
> > > > > <martini@foxinternet.net>
> > > > > >
> > > > > > What resistance do you read between the battery cable and
ground.
> > Be
> > > > sure
> > > > > > to take the measurement with the leads swapped as well as
standard
> > > > > polarity,
> > > > > > i.e. red lead to + and black to -.. If you are NOT using a
> digital
> > > VOM,
> > > > > > then also take values in both polarities in more than one RANGE
on
> > the
> > > > VOM
> > > > > > (active devices - diodes /transistors - are non-linear.. give
you
> a
> > > good
> > > > > > clue if the value changes). You may have another noise
suppression
> > > diode
> > > > > > somewhere, and/or an RC type (Band Pass) noise filter , with
> > possibly
> > > a
> > > > > bad
> > > > > > capacitor in it.
> > > > > >
> > > > > > Let me know what you get.
> > > > > >
> > > > > > Luc Martini
> > > > > > ----- Original Message -----
> > > > > > From: "David J. Spencer" <djs@54Transmission.com>
> > > > > > To: <avionics-list@matronics.com>
> > > > > > Subject: Avionics-List: Battery Solenoid (Relay)
> > > > > >
> > > > > >
> > > > > > > --> Avionics-List message posted by: "David J. Spencer"
> > > > > > <djs@54Transmission.com>
> > > > > > >
> > > > > > > Hi all...
> > > > > > >
> > > > > > > Has anyone ever replaced the battery relay on their Beech
A23-24
> > > Super
> > > > > > III?
> > > > > > >
> > > > > > > My relay seems to work fine, but is 36 y/o and uses a Kipvolt
> > > Voltage
> > > > > > > suppressor (diode) to eliminate voltage spikes flushing
through
> > the
> > > > > > system.
> > > > > > >
> > > > > > > I am replacing the battery, ground and starter cables with
new
> > > cable
> > > > > (AC
> > > > > > > grade #0 wire for the 40 amp system) and am wondering if
anyone
> > has
> > > > put
> > > > > > in
> > > > > > > a
> > > > > > > new Aircraft grade battery relay from an aircraft supply
> (Spruce)
> > > > > source
> > > > > > > battery relay in place of ours.
> > > > > > >
> > > > > > > I can currently remove the battery, diode and battery rely
and
> > get
> > > > > > current
> > > > > > > continuity (VOM) through the system from the positive cable
to
> > the
> > > > > > > negative cable or any
> > > > > > > ground... everything is off... i.e switches, breaker etc.
This
> > is
> > > > what
> > > > > > > some
> > > > > > > people think is causing a "hum" in the radios. The "hum" is
> > > present
> > > > > with
> > > > > > > the engine off and running the radios off a fully charged
> > battery.
> > > .
> > > > > > > Additionally, using the AC voltage test setup on the VOM I
can
> > > detect
> > > > > > > current flow between the positive cable and ground... any
> ground.
> > > > > > >
> > > > > > >
> > > > > > > I'm using certer point grounding, but all the avionics manual
> > > > articles
> > > > > > > point
> > > > > > > to RMI induced noise through the hull by poor shielding on
the
> DC
> > > > power
> > > > > > > lines.
> > > > > > >
> > > > > > > Beech doesn't seem to have these parts anymore.
> > > > > > >
> > > > > > > All comments welcomed...
> > > > > > >
> > > > > > > David J. Spencer
> > > > > > > Super3
> > > > > > > djs@54Transmission.com
> > > > > > >
> > > > > > >
> > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >
> >
> >
>
>
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| Subject: | Re: Battery Solenoid (Relay) |
--> Avionics-List message posted by: "Martini Luc J.R." <martini@foxinternet.net>
Hi again
I forget to mention something about what you said you used for Coax. Triax
is of course a Double Shielded form of Coax, and has the proper 50 Ohm
impedance just like RG-58 (which also comes in a doble shielded variety).
However, it has an additional insulation layer between the first and second
shield. Obviously, that makes the coax larger in diameter and heavier.
The cable was actually designed for use on Cable TV systems. By putting an
insulator between the shields, they not only kept the better noise immunity
that double shielding provided, but more importantly, could use the shields
as CONDUCTORS the send power to the INLINE AMPS that the cables systems need
to install every 1/2 mile or so to compensate for line losses i.e, one
shield carried a +28VDC and the other was the Power as well as Signal
Ground.. cute eh?
The problem in airplanes with TRIAX, is that they are a BITCH to terminate
at coaxial connectors properly. The greatest problem is because they used
plastic that melt rather readily at soldering iron temperatures, while the
better forms of RG-58 used nylon center conductors. And, stripping that
2nd layer of plastic so that you can join the braids before jamming them
into a connector can get REALLY MESSY and at the very least result in one
hell of a lot of serious cussing.
Luc
----- Original Message -----
From: "David J. Spencer" <djs@54Transmission.com>
Subject: Re: Avionics-List: Battery Solenoid (Relay)
> --> Avionics-List message posted by: "David J. Spencer"
<djs@54Transmission.com>
>
> Wow... what a wealth of information... You will never know how much this
is
> helping and I really appreciate your input.
>
> First of all this is a single engine plane (1967 Beech Musketeer, 200 hp
> Lycoming with fuel injection, A23-24 or Super III), so I only have one
> alternator. Now to the cycling which I mentioned. The VR was a contact
> type which I replaced with a Zeftronic unit. The cycling continued. I
then
> replaced the OV regulator with the matched Zeftronic solid state affair
and
> the cycling has stopped. I thought it might be one or the other as
nothing
> except the alternator and intercom were running when I last got fed up
with
> the noise.
>
> Turn off the alternator and the noise went away. It just made sense and
the
> VR & OV were both original equipment and 36+ years old.
>
> Thank you... You are correct for correcting me about resistance with or
> without inline devices... I just wasn't thinking when I said there is no
> difference as I always try to simplify the circuit to it's barest
essentials
> and then load on devices until I find a problem. Just my untrained
> methodology.
>
> I will run the amperage test when I get some new battery cable installed.
I
> bought #4 as it met the continuous usage requirements as per the chart on
> page 1-10 of Robert G. Horan's "Avionics Installation Handbook"...
HOWEVER,
> the plane came with #0 wire and I am going to replace it with #0 wire.
The
> run from the battery to the starter solenoid is about 12 feet (12 volt
> system) and then another 5 feet to the starter. The alternator is a 40
amp
> unit, but my guess is that the amperage on engine start may be high enough
> to warrant the heavier cable. Anyway what the hell it's just money and it
> "might" prevent something I don't understand is going on... safe is better
> than crispy.
>
> Now to the audio panel. I have a Terra TMA 230 with a marker beacon and
two
> Terra TXN-960 NavComs with glide slopes and ILS which I call a radio
stack.
> I also have a KLN-88, cooling fan, King KT-76 transponder, Sigtronics
> SPA-400 intercom and Collins RCR-650/IND 650 ADF. The audio panel has
three
> audio grounds (connected) and one chassis ground.
>
> AND THANK YOU VERY MUCH -- YOU JUST JOGGED MY MEMORY-- THE GROUNDS FOR
THE
> ADF, TRANSPONDER & COOLING FAN ARE NOT ON THE CENTERPOINT SYSTEM. I also
> have not put a ground on the radio trays themselves... I think I should.
>
> Also, my centerpoint system is a terminal block where all the posts are
> connected to the same frame point as the ground. This allowed me to
create
> a neat little area where all the grounds (except the ones I just
mentioned)
> are located. The intercom requires insulating all the headset jacks (with
> isolation washers) and using the centerpoint ground.
>
> Now to the Cone of Static... below is a diagram of the airport in
> relationship to some 1600' AGL radio, TV & Microwave transmission towers
> which are South of the field about 5 miles. The airport is directly
between
> the towers and Downtown Dallas Texas. Is it possible that the towers
could
> be transmitting a directional signal toward downtown?
>
>
> ++++
>
> +++++ Radio Transmission towers (~15 @ 1600' AGL)
>
> +++++
>
>
about
> five miles to towers
>
>
> |
> |
> | Runway
(17/35)
> |
> |
>
>
> about three miles
>
> DOWNTOWN DALLAS TEXAS
>
> As for large metallic structures...there are two hangars built by Howard
> Hughes for something really big right on the 17/35 runway. Other than
that
> there is an FBI/U.S. Customs helicopter hangar (which tends to be rather a
> secretive place) on the South end of the field and a medium sized strip
mall
> just across a highway to the South. There is also a six story Wells Fargo
> Bank down by the FBI.
>
> There is a National Guard Armory on the West side of the field which, I
> believe has some radio antennae sticking up in the wooded area adjacent to
> it... I'll check on the way home. My wife (she's a pilot also) says she
> thinks the bank tower has dish antennae on it... either the bank or the
FBI.
> That's her side of the plane so I never look out there, because I don't
want
> to see what she's going to hit, and will check on it on way home.
>
> The antennas are well grounded, but are on the aft slope of the top of the
> fuselage (fuselage much like a V-35 Bonanza). After putting in the ADF
> which required triaxial cable I changed EVERYTHING to triaxial as it just
> seemed the logical thing to do.
>
> They are too close together (about 2 feet apart), but are about 5 feet aft
> of the Loran antenna. The transponder is under the foward fuselage (blade
> type) and the ADF & marker beacon are on the bottom aft fuselage. The
> aftmost comm antenna is very close to the vertical stabilizer which has an
> ABS plastic shroud on the leading edge to affect airflow. I never thought
> much about the static from plastic as all I've read indicates that our
plane
> is too slow... we cruise at ~145-150 mph with take-off and climb at 90-100
> mph. Should I install some static wicks?
>
> We only get this static garbage at this airport... no where else we have
> flown has given us any problems and we have been into some strange places
> like the Arizona & New Mexico desert and along the U.S./ Mexico border.
>
> You will never know how much you are helping... I tend to be a rather
> tenacious person and want very much to understand as much as possible
about
> what is going on and how to eliminate it... if possible.
>
> David
>
>
> ----- Original Message -----
> From: "Martini Luc J.R." <martini@foxinternet.net>
> To: <avionics-list@matronics.com>
> Subject: Re: Avionics-List: Battery Solenoid (Relay)
>
>
> > --> Avionics-List message posted by: "Martini Luc J.R."
> <martini@foxinternet.net>
> >
> > Hello again
> >
> > There can be a very considerable difference in resitance readings of a
VOM
> > for forward v. reverse polarity if you have an "Active Device" in the
> > circuit... i.e. a Diode, or a Transistor. Looking from the battery,
you
> > could be looking at several of these, (diodes or transistors) which are
> > used for noise suppression, voltage spike protection, even internally
in
> a
> > voltage regulator, and on the BATTERY BUS CIRCUIT, i.e, not isolated by
a
> > circuit breaker.
> >
> > If there is No change as you indicated, that simply verifies that you
> likely
> > DO NOT have an Active Device in the Battery Bus Circuit, since Active
> > Devices are very NON LINEAR, i.e., the reading you get on a VOM is
> typically
> > MUCH higher in one polarity than the other.
> >
> > If your VOM has a 1 amp direct reading capability, the way to proceed
is
> to
> > disconnected the + lead from the battery. Set your VOM to DC CURRENT
> > (milliaps or amps) & to the 1 Amp RANGE. Then Connect the VOM in SERIES
> > with the battery, i.e., VOM - lead to battery cable (where the LOAD is),
> and
> > + lead to the battery + lead (Current Source).
> >
> > The reading you will get will be in either MILLIAMPS (ma) or AMPS (A)..
> > depending on your meter...if the scale is calibrated in (ma), move the
> > decimal place to the right 3 spaces (X 1000) for (amps)
> >
> > If you are using your fully charged aircraft battery,. you should get
> 1.09
> > Amps showing on the meter.:
> >
> > 12 VDC/11 OHMS = 1.09 AMPS.
> >
> > Note that if you use external power the voltage might be higher, up to
14
> > volts.. that might damage your VOM since that is 1.3 Amps.
> >
> > You may have done this already according to your note, but you read the
> > VOLTS RANGE, rather than the AMPS RANGE on the dial. Since each meter
is
> > different, I have no way of knowing what the .245 you referred to really
> is.
> >
> > The nice thing about using a CURRENT METER is that you can leave it
hooked
> > up and go disconnect various things that power goes to, i.e voltage
> > regulators, bulkhead connectors, circuit breakers, etc. and with a quick
> > check see if the current dropped to ZERO.... BINGO... your problem is in
> > THAT CIRCUIT.
> >
> > As to your question about Avionics Signal and Power Grounds. NO, they
> MUST
> > be connected together at ONE and ONLY one place for noise immunity...
> also
> > helps with lighning protection. Signal ground is not the same as AUDIO
> > ground.
> >
> > That is not to say that Avionics Shops do things right... as you have
> found
> > out.
> >
> > There is one other thing I should tell you about. Audio Panels are an
> even
> > MORE complicated item. In Audio Panels, they may have as many as 2 MORE
> > types of Grounds. King (KMA-24) is famous for this. You have to Isolate
> the
> > AUDIO GROUNDS as well. and may have to isolate the Pilot and Co-pilot
> audio
> > from ANY OTHER audio ground, as well as isolation from CHASIS GROUND.
> > These suckers can be real bears, and the source of Noise PICKUP (from
> > external sources such as motors, sparks (like bad shielding on spark
plug
> > wires) and even external to the aircraft.. industrial sources.
> >
> > The Noise Zone you mention is intriguing. There are two ways of looking
> at
> > the problem.. 1) that there exists a NOISE SOURCE in that area, or 2),
> that
> > there exists a SHIELD from radiation.
> >
> > I believe the first is what everybody has been focused on. However, the
> > second is just as likely if not more so. For example, if there is a
> > significant magnetic disturbance in the area, or a very large metalic
> > structure in the area, or a hill with a lot of iron content.. etc. etc.
> > these can shield the background RF Noise Level The Automatic Gain
> Control
> > (AGC) circuits in you radios, and/or audio panel, would compensate by
> > INCREASING the GAIN... that would result in audio STATIC...exactly like
> what
> > you get when listening to your AM radio in the car when you drive
through
> a
> > tunnel.
> >
> > I got the point you made that you had EVERYTHING disconnected except
the
> > Battery and the Avionics DC bus and of course the radios that power
them..
> > One thing you should also do, is turn of your Transponder. Also, if the
> > Antenna Coax for the Transponder and the DME (if you have one) are run
> > parallel with other wiring bundles, that can be a source of severe
static.
> > I always use Double Shielded Coax for these devices... some Av Shops do
> > not... and if I have to cross a wire bundle, I do it at as close to 90
> > degrees as I can.(the Electric and Magnetic Fields no not couple to the
> > other cable when; you do that) Obviously it pays to keep these Coax
> leads
> > as short as possible (but must generally be no shorter than 3 feet (1/2
> wave
> > length).
> >
> > Another general practice to follow is good GROUND PLANES for the
antennas.
> > What that means generally, is as much flat metal around the antenna as
> your
> > airplane and avionics can afford; keep radiating elements like DME and
> > Transponder seperated by 6' from each other.. as well as from very low
> > signal sources like LORAN, GPS...Keep the Comm antenna away from those
as
> > well... and strangely enough, keep these well away and UP-STREAM
> > (airstream) from non-electrically conductive surfaces such as
Plexiglass,
> > Fiberglass etc. (these create static electricity that can couple the
> > discharge via inonizatiotion of the airstream) Then, have a Good Low
> ohmic
> > contact for the antennas. That means cleaning away all paint where the
> > antenna mounts, and Alodining the area. and on the INSIDE of the
> airplane,
> > make sure that your have a good clean contact in like fashion for the
> > antenna mounting nuts/bolts.
> >
> > I just received another e-mail from you... about the odd charging habits
> of
> > your airplane. Keep in mind, that a fully charged battery is 12 VDC.
> > However, your voltage regulator puts out between 13.5 and 14.00 volts
> > depending on the current draw, and the internal setting of you voltage
> > regulator. You would be surprised at the variation in "Idling Current"
> from
> > one Regulator to the next. So, it does NOT surprise me that even after
> > starting your engines with a full battery, that they do a little chargin
> for
> > a while. What DOES surprise me is the CYCLING you mentioned. That was
> > common in the old days of RELAY type voltage regulagtors, but NOT for
> Solid
> > state Alternator Regulators.
> >
> > Do you have some sort of switching arangement for left/right engine
> > alternators?
> >
> > Luc
> >
> >
> > ----- Original Message -----
> > From: "David J. Spencer" <djs@54Transmission.com>
> > To: <avionics-list@matronics.com>
> > Subject: Re: Avionics-List: Battery Solenoid (Relay)
> >
> >
> > > --> Avionics-List message posted by: "David J. Spencer"
> > <djs@54Transmission.com>
> > >
> > > Luc...
> > >
> > > The resistance didn't change with a reverse in polarity... it rarely
> does.
> > >
> > > My VOM has a 1 amp capability. When I set it to AC voltage and ran a
> > check
> > > with the +/- cables I got .245 volt flow in either direction.
> > >
> > > You raise an interesting point about the two different types of
> grounds...
> > > power and audio. Both are separated in the wiring harness, but
> connected
> > to
> > > the same center point ground. Should there be two center point
grounds?
> > >
> > > Everything is very clean as I just rebuilt the wiring harness. I have
> had
> > > it out twice and rechecked for faulty wiring or shielding touching the
> > > center wire and it checks out just fine.
> > >
> > > With the DC power source hooked directly to the power cable (I come
off
> > the
> > > power bus with one power cable to the audio panel, 2 NavComs,
> transponder,
> > > ADF and intercom though another set of breakers) to the radio stack,
the
> > > only thing I eliminated was the battery and the associated wiring...
all
> > > other noise sources (motors, alternator, gyros, etc.) were always off.
> I
> > > was getting the hum just off the battery power with no other motors,
> > > solenoids, regulators, gyros or anything turned on even connected.
> > >
> > > The + cable was the one with the crimp in it. The negative cable is
> only
> > > about 18" long and connected to the frame.
> > >
> > > I have not checked the grounding strap from the engine to the firewall
> > > within the last two months, but will be checking that also along with
> the
> > > starter cables, ammeter cables (which I found had some "burned spots"
on
> > > them which was hidden from view until you "unbundled" all the wiring)
> and
> > > installing an AmeriKing DC filter and Alternator filter. I've always
> > though
> > >
> > > Last year I replaced all the antenna cables as I found them to be
> bundled
> > > and taped to the + power cable. I also replaced all the comm antennae
> > > (fiberglass and cracked) with stainless steel, which helped a lot.
The
> > > controlled field I fly out of has a "cone of static" which many
complain
> > > about, but the FAA and FCC can't seem to isolate or do anything about,
> but
> > > rather claim it's everybody's radios... when you lift off, sometimes,
> the
> > > static is so bad you have to turn off the radios...
> > >
> > > I also replaced the alternator, voltage regulator and OV regulator
plus
> > all
> > > the associated wiring as some Avionics moron had butt spliced the
field
> > wire
> > > "INSIDE" the firewall cannon plug. The butt splice was broken and, of
> > > course, the field wire was going to ground. After 3 avionics shops
> > checked
> > > my alternator I took it out myself and found 3 diodes were bad...
> > > AeroElectric found that one more was bad when they replaced my
> alternator
> > > with an upgraded version with larger bearings.
> > >
> > > Yesterday as I pulled out the + battery power cable, I found all the
> > lights,
> > > strobe, electric fuel pump, and fuel sensors taped (relatively new
> looking
> > > tape) to the + power cable. Needless to say, during it's 36 year
> > existence,
> > > maintenance has always been done in FAA certified shops and done with
a
> > very
> > > high level of poor quality.
> > >
> > > I honestly think this is a wiring problem relative to 36 y/o wire, but
I
> > > won't know until I get all the wiring replaced and according to Beech
> > wiring
> > > diagram specifications.
> > >
> > > Thanks for you help and input...
> > >
> > > David J. Spencer
> > > Super3
> > > djs@54Transmission.com
> > >
> > >
> > > ----- Original Message -----
> > > From: "Martini Luc J.R." <martini@foxinternet.net>
> > > To: <avionics-list@matronics.com>
> > > Subject: Re: Avionics-List: Battery Solenoid (Relay)
> > >
> > >
> > > > --> Avionics-List message posted by: "Martini Luc J.R."
> > > <martini@foxinternet.net>
> > > >
> > > > What was the reverse polarity reading? I assume since you did not
> give
> > a
> > > > value for another range on the VOM, that it was a Digitial Type.
> > > >
> > > > Do you have a 1 amp Current meter? From the ohmic check, that's
about
> > the
> > > > current you are drawing if this is a DC load. If not, hook a 100
ohm
> > > > resistor in series with the + battery Cable and measure the voltage
> > drop
> > > > across the resistor.
> > > >
> > > > As far as Radio noise in general GOOD GROUNDS (very low ohmic
contact)
> > are
> > > > EVERYTHING.
> > > >
> > > > However, there are frequently 2 ground levels, SIGNAL ground and
POWER
> > > > ground. Great care must be taken when assembling your avionics to
> keep
> > > > these two seperate, and connect them only at a SINGLE POINT ground.
> > > >
> > > > It is not a bad idea to stick your head under the panel, and clean
the
> > > > single point avionics ground to make sure the spade lugs and washers
> > are
> > > > not oxidized (high ohmic contact)
> > > >
> > > > It does not surprise me that with EXTERNAL DC power, that you do
NOT
> > have
> > > > radio hum. since your do NOT have a source of noise..
> > > generator/alternator,
> > > > motors, etc.
> > > >
> > > > You did not mention if it was the + or the - battery lead that had a
> > crimp
> > > > splice in it. If it was in the + lead. other than creating a
voltage
> > > > drop... which would be reflected to the voltage regulator, i.e. the
> > > > generator/alternator would be putting out more voltage than it
should
> > > > because it senses a Battery slightly low voltage condition. If on
> the
> > > > other hand it was on the - side. as far as the radios go, it would
be
> > > like
> > > > putting a resistance between the - battery terminal and Chasis
Ground.
> > > This
> > > > could conceiveably cause the noise floor to be raised...but not
likely
> > if
> > > > yourGenrator/Alternator grouind is good... By the way... have to
> > checked
> > > > that to make sure you have a good & clean grounding strap from the
> > engine
> > > to
> > > > the firewall ??
> > > >
> > > > Luc
> > > >
> > > >
> > > > ssage -----
> > > > From: "David J. Spencer" <djs@54Transmission.com>
> > > > To: <avionics-list@matronics.com>
> > > > Subject: Re: Avionics-List: Battery Solenoid (Relay)
> > > >
> > > >
> > > > > --> Avionics-List message posted by: "David J. Spencer"
> > > > <djs@54Transmission.com>
> > > > >
> > > > > Luc...
> > > > >
> > > > > There was approximately 11 ohms between the + & - with the correct
> > > > polarity
> > > > > hook up on the VOM.
> > > > >
> > > > > I took out the battery cable yesterday and found a split in the
> > > insulation
> > > > > about 3/8" long which had been taped over. The cable itself had
> been
> > > > > "crimped" creating a bulge and part of the internal wiring was
> broken
> > at
> > > > > that point.
> > > > >
> > > > > As best I could tell this open area was not laying on the skin but
,
> > > > rather,
> > > > > pointing away from the skin as the cable lay on the belly of the
> > plane.
> > > > >
> > > > > This is being corrected with new wiring and proper attachments.
> > > > >
> > > > > I hooked the radios up to a DC power source i.e. they are isolated
> > from
> > > > > anything (except the antenna)... and the hum went away.
> > > > >
> > > > > David J. Spencer
> > > > > Super3
> > > > > djs@54Transmission.com
> > > > >
> > > > > ----- Original Message -----
> > > > > From: "Martini Luc J.R." <martini@foxinternet.net>
> > > > > To: <avionics-list@matronics.com>
> > > > > Subject: Re: Avionics-List: Battery Solenoid (Relay)
> > > > >
> > > > >
> > > > > > --> Avionics-List message posted by: "Martini Luc J.R."
> > > > > <martini@foxinternet.net>
> > > > > >
> > > > > > What resistance do you read between the battery cable and
ground.
> > Be
> > > > sure
> > > > > > to take the measurement with the leads swapped as well as
standard
> > > > > polarity,
> > > > > > i.e. red lead to + and black to -.. If you are NOT using a
> digital
> > > VOM,
> > > > > > then also take values in both polarities in more than one RANGE
on
> > the
> > > > VOM
> > > > > > (active devices - diodes /transistors - are non-linear.. give
you
> a
> > > good
> > > > > > clue if the value changes). You may have another noise
suppression
> > > diode
> > > > > > somewhere, and/or an RC type (Band Pass) noise filter , with
> > possibly
> > > a
> > > > > bad
> > > > > > capacitor in it.
> > > > > >
> > > > > > Let me know what you get.
> > > > > >
> > > > > > Luc Martini
> > > > > > ----- Original Message -----
> > > > > > From: "David J. Spencer" <djs@54Transmission.com>
> > > > > > To: <avionics-list@matronics.com>
> > > > > > Subject: Avionics-List: Battery Solenoid (Relay)
> > > > > >
> > > > > >
> > > > > > > --> Avionics-List message posted by: "David J. Spencer"
> > > > > > <djs@54Transmission.com>
> > > > > > >
> > > > > > > Hi all...
> > > > > > >
> > > > > > > Has anyone ever replaced the battery relay on their Beech
A23-24
> > > Super
> > > > > > III?
> > > > > > >
> > > > > > > My relay seems to work fine, but is 36 y/o and uses a Kipvolt
> > > Voltage
> > > > > > > suppressor (diode) to eliminate voltage spikes flushing
through
> > the
> > > > > > system.
> > > > > > >
> > > > > > > I am replacing the battery, ground and starter cables with
new
> > > cable
> > > > > (AC
> > > > > > > grade #0 wire for the 40 amp system) and am wondering if
anyone
> > has
> > > > put
> > > > > > in
> > > > > > > a
> > > > > > > new Aircraft grade battery relay from an aircraft supply
> (Spruce)
> > > > > source
> > > > > > > battery relay in place of ours.
> > > > > > >
> > > > > > > I can currently remove the battery, diode and battery rely
and
> > get
> > > > > > current
> > > > > > > continuity (VOM) through the system from the positive cable
to
> > the
> > > > > > > negative cable or any
> > > > > > > ground... everything is off... i.e switches, breaker etc.
This
> > is
> > > > what
> > > > > > > some
> > > > > > > people think is causing a "hum" in the radios. The "hum" is
> > > present
> > > > > with
> > > > > > > the engine off and running the radios off a fully charged
> > battery.
> > > .
> > > > > > > Additionally, using the AC voltage test setup on the VOM I
can
> > > detect
> > > > > > > current flow between the positive cable and ground... any
> ground.
> > > > > > >
> > > > > > >
> > > > > > > I'm using certer point grounding, but all the avionics manual
> > > > articles
> > > > > > > point
> > > > > > > to RMI induced noise through the hull by poor shielding on
the
> DC
> > > > power
> > > > > > > lines.
> > > > > > >
> > > > > > > Beech doesn't seem to have these parts anymore.
> > > > > > >
> > > > > > > All comments welcomed...
> > > > > > >
> > > > > > > David J. Spencer
> > > > > > > Super3
> > > > > > > djs@54Transmission.com
> > > > > > >
> > > > > > >
> > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >
> >
> >
>
>
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