Today's Message Index:
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1. 09:08 AM - Re: Hand-Held NAV-COM (Lynn Cole)
2. 09:34 AM - Re: B&C alternator diagnosis (Robert L. Nuckolls, III)
3. 12:32 PM - Re: turn coordinator causing noise in headset (jerrytex)
4. 01:11 PM - radio interference? (thomas sargent)
5. 02:41 PM - vhf transponder interference (jappie)
6. 08:02 PM - Re: B&C alternator diagnosis (Henry Hallam)
Message 1
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Subject: | Re: Hand-Held NAV-COM |
Thanks!
-----
Lynn Cole
LynnCole@foxvalley.net
On Oct 28, 2012, at 2:22 PM, Robert L. Nuckolls, III wrote:
> At 12:03 PM 10/27/2012, you wrote:
>> I have an old hand-held NAV-COM marketed by Satellite Technology
Services, Inc. of St. Louis, MO. It works well on 720 channels of COM
and 200 channels of NAV, but the center pin of the external power-supply
jack is broken. It has a removable battery pack that takes 6 AA
batteries. The instruction manual talks about a 7.2-volt NiCad battery
pack, but it works well using 6 alkaline batteries (9 volts). However,
it uses up the batteries quite rapidly, and I would like to find a way
of attaching an external power supply.
>>
>> I checked the web and found 3 references to the company, a BBB
report, a lawsuit, and a patent assignment. Apparently they don't have
a web site. I don't know whether they still support the radio.
>>
>> My options seem to be:
>> 1. Replace the power-supply jack. It seems to be a special jack
that is soldered into the main board. I have not been able to find the
correct jack from any of the usual electronics suppliers.
>>
>> 2. Remove the jack, solder a pigtail to the board, and connect the
pigtail to a new jack that would dangle from the case.
>>
>> 3. Modify the battery pack, possibly by making a pair of dummy
batteries that would connect to an external power jack. This is
attractive because the instruction manual says to disconnect the battery
pack (to avoid damaging it) when the external power supply is used.
>>
>> Whichever option I choose I will need two power supplies, one to
connect to connect to the cigarette-lighter in the airplane, and the
other to connect to the 120-V AC power. Any suggestions for these?
>
> Search on STS "AV-7600" and you'll get more hits.
>
> A friend of mine in Wichita works on hand-helds and
> might be able to repair/replace the existing jack.
>
> If you go the pigtail route, you can power up from
> a/c mains with a power supply like this:
>
> http://tinyurl.com/963xg74
>
> there are many similar models at very reasonable prices
> on eBay.
>
> You probably don't want to apply a 14-15 volt bus
> directly to this radio. Some sort of boost-buck
> dc/dc converter that will give you a constant 12v
> out for a range of inputs that goes both above and
> below the output setting.
>
> http://tinyurl.com/9dqt39k
>
> Bob . . .
>
>
>
>> -----
>> Lynn Cole
>> LynnCole@foxvalley.net
>>
>>
>>
>>
>>
>> AeroElectric-List Email Forum -
>>
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>>
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> 10/27/12
>
> Bob . . .
>
>
>
>
Message 2
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Subject: | Re: B&C alternator diagnosis |
>Adjusting the regulator's screw while all
>this was happening didn't seem to change much.
This alternator output is too small to be set
reliably at combinations of low rpm and significant
load.
>So now I'm at a loss - it seems to be working again. Do you think
>it's still a good idea to replace the regulator? The only other thing
>I noticed is that one screw terminal on the battery was not tight -
>not terribly loose, but I could undo it with just my fingers. I guess
>I will put it all back together with a trusted voltmeter in the
>cockpit and go fly in VMC for a while, but I'd love to hear ideas.
The regulator can be accurately adjusted ONLY
with a fully charged battery, very light sytem
loads (suggest 2A or less) and SIGNIFICANT rpm,
like something 2000 or better.
The alternator is exceedingly robust . . . very
unlikely to fail. The rectifier/regulator has
a very low parts count, is potted for mechanical
ruggedness and is vulnerable to few stresses OTHER
than overheat.
If it has a history of good performance (Not accurately
known without an accurate voltmeter) what appears to
be a transient failure may have been a poor connection
that got 'cured' as a product of removal and replacement.
If it were my airplane, I'd fit it with a voltmeter of
trustworthy accuracy. Also, a low voltage warning
light so that future failures are not a surprise.
Find out where the system voltage stabilizes under light
load after some sustained operations . . . say just before
descent to land on your next trip. Make little tweeks
of the potentiometer setting based on these observations.
Shoot for 14.2 but settle for 14.0 to 14.5.
The successful resolution starts with trustworthy
measurement and observation. Where's your rectifier/
regulator mounted? Where does it tie into the electrical
system? Do you have a wiring diagram for this airplane
that can be scanned/shared?
Bob . . .
Message 3
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Subject: | Re: turn coordinator causing noise in headset |
As I mentioned earlier, I have had my fair share of electrical issues. It appears
that this noise is the result of or partially caused by low voltage directly
related to another electrical problem.
The original builder wired in a hotbox. In the hotbox instructions it says to run
the two AC lines from the alternator to the hotbox. Apparently some of the
Hotboxes had the regulator attached to them and jumpers are need to connect to
the regulator. In my case, the regulator is on the firewall. The original builder
split the the two AC lines with a crimp connector. He had two AC lines going
to the hotbox which were not needed and then had two going to the the regulator
with the 12 volt DC line output going to the charging circuit. I discovered
that these crimp connectors had bad connections causing resistance and ultimately
melted the AC wires together essentially shorting out the AC current.
That caused the battery to not charge and caused low voltage. I eliminated the
split and ran the AC lines directly to the regulator, crimped and soldered all
the connections and the alternator is now charging the battery. I charged the
battery with a good battery charger and flew yesterday. It appears that the
noise is either gone or lessened to the point that I cannot hear over the engine.
So I guess that low voltage was the main culprit with the melted wires causing
the low voltage situation by not charging the battery. Thanks for all the
thoughts and advice on this.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=386225#386225
Message 4
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Subject: | radio interference? |
At Ryan field yesterday a fellow I know who has done an incredible job
building a perfect Hatz bi-plane asked me for help with a very odd radio
problem. He has about 10 flights on it so far.
His brand new ICOM radio produces only very soft, badly garbled reception
when his engine (Lyc. O-290) is running. He can't talk to the tower when
he's on-airport without stopping the engine. The really odd part is that
the same is true if he uses a hand-held radio. (The ICOM has been benched
checked by an official shop and looks fine.)
His belly mounted antenna was obviously poor since it had a 90 deg. bend it
it about 2 inches after it emerges from the plane. It has what looks like
a good ground plane. He's switching to a plain, straight whip antenna for
next flight. But I doubt it will work any better given the performance of
the hand-held. He was also going to fly it once with the magnetos shorted
at the magneto (so the wires going from the mag to the switch will be
disconnected, thinking they may be radiating somehow).
Engine installation looks beautiful, like the rest of the plane. Grounding
looks good, all parts are real aircraft parts, spark plugs, wires, etc.
Any ideas?
--
Tom Sargent
Message 5
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Subject: | vhf transponder interference |
Hello everyone
I'm a new member here and looking for some help on a problem I've noticed approx.
2 years ago.
1- When I transmit on my Garmin GNC 250XL, some gauges on my panel go haywire.
ie: Mitchell fuel level indicator.
2- When I trasnmit, ATC tells me my altitude changes on his radar ( transponder
Garmin GTX-320) encoder AK-350.
3- When I put my X-Ponder from Off to any position ( SBY, ON, ALT ) a "White" noise
can be heard in my headset ( only while receiving).
4-Receiving deteriorate as the flight goes.
airplane all fiberglass, C-GGYY to see pictures
Thank you
Jean-Pierre
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=386234#386234
Message 6
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Subject: | Re: B&C alternator diagnosis |
On Mon, Oct 29, 2012 at 9:33 AM, Robert L. Nuckolls, III
<nuckolls.bob@aeroelectric.com> wrote:
> <nuckolls.bob@aeroelectric.com>
>
>
>> Adjusting the regulator's screw while all
>> this was happening didn't seem to change much.
>
>
> This alternator output is too small to be set
> reliably at combinations of low rpm and significant
> load.
Thanks for the insights! I also found this doc on B&C's site:
http://www.bandc.biz/pdfs/sd8trbreva.pdf that agrees with everything
you've said.
> The successful resolution starts with trustworthy
> measurement and observation. Where's your rectifier/
> regulator mounted? Where does it tie into the electrical
> system? Do you have a wiring diagram for this airplane
> that can be scanned/shared?
>
>
> Bob . . .
I will definitely be fitting a reliable voltmeter and warning light.
Unfortunately I don't have a wiring diagram, though I'm working on
putting one together from my own notes taken during maintenance and
upgrades. My rectifier/regulator is mounted on the engine side of the
firewall, in what I think is a relatively cool location (on the high
pressure side of the updraft cooling system). The positive output
goes via a 14 AWG wire to a 10-amp CB on the instrument panel and from
there to the positive battery terminal (battery in the nose of the
canard-pusher airplane). The negative output goes to a general ground
terminal on the engine mount frame and from there via a similar 14 AWG
wire to the negative battery terminal. The instrument power bus is
connected to the battery terminals by another set of wires, and
there's a third set for the electronic ignition.
Any reason not to tune the regulator voltage setpoint on the bench
with a constant-current bench supply on the blue wires and my airplane
battery on the red+black?
Thanks again for the advice.
Henry
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