Today's Message Index:
----------------------
1. 03:30 PM - NARCO Help ()
2. 04:14 PM - Re: NARCO Help (Wayne Sweet)
3. 05:08 PM - Re: NARCO Help (Fred Fillinger)
4. 05:52 PM - Re: NARCO Help (Mike Larkin)
Message 1
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--> Avionics-List message posted by: <bakerocb@cox.net>
8/18/2005
Hello Avionics Experts, My friend has a Cessna 172 with a NARCO CP 136 TSO
audio control panel in it. One selects which radio to transmit on or which
receivers to listen to by pushing in round buttons. No intercom is
incorporated.
He has been having VHF radio transmitter problems that appear after an hour
or so of flight. Since both transmitters send out just basic carrier with no
voice included after this failure mode happens it has been assumed that the
failure may be heat related and caused within the audio panel since both
transmitters are affected the same way at the same time.
When the problem was discussed with a local avionics shop their analysis was
that it could not be a heat related problem within the audio panel because
the audio panel was a simple mechanical device with no electronics inside.
Nevertheless their solution was to replace the audio control panel with a
modern PS Engineering audio control panel and intercom at the cost of big
bucks.
Can anyone confirm this description of the inner workings and hidden
mechanisms of this audio control panel? Can anyone come up with a better
(cheaper) cure than the one described above? Thank you.
OC
Message 2
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--> Avionics-List message posted by: "Wayne Sweet" <w_sweet@comcast.net>
I had that problem when I first wired my MustangII. The audio out from the
mic was grounded through a pinched wired to ground behind the instrument
panel. Does both pilot and copilot have that same problem?
Find the audio out wire from the audio panel (btw, I have found NARCO stuff
to be CRAP!) and from the affected mic and check it with a multimeter to
ground. If it shows continuity to ground, that's the problem
Wayne
----- Original Message -----
From: <bakerocb@cox.net>
Subject: Avionics-List: NARCO Help
> --> Avionics-List message posted by: <bakerocb@cox.net>
>
> 8/18/2005
>
> Hello Avionics Experts, My friend has a Cessna 172 with a NARCO CP 136
> TSO
> audio control panel in it. One selects which radio to transmit on or which
> receivers to listen to by pushing in round buttons. No intercom is
> incorporated.
>
> He has been having VHF radio transmitter problems that appear after an
> hour
> or so of flight. Since both transmitters send out just basic carrier with
> no
> voice included after this failure mode happens it has been assumed that
> the
> failure may be heat related and caused within the audio panel since both
> transmitters are affected the same way at the same time.
>
> When the problem was discussed with a local avionics shop their analysis
> was
> that it could not be a heat related problem within the audio panel because
> the audio panel was a simple mechanical device with no electronics inside.
> Nevertheless their solution was to replace the audio control panel with a
> modern PS Engineering audio control panel and intercom at the cost of big
> bucks.
>
> Can anyone confirm this description of the inner workings and hidden
> mechanisms of this audio control panel? Can anyone come up with a better
> (cheaper) cure than the one described above? Thank you.
>
> OC
>
>
>
Message 3
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--> Avionics-List message posted by: "Fred Fillinger" <n3eu@comcast.net>
> --> Avionics-List message posted by: <bakerocb@cox.net>
> ...
> He has been having VHF radio transmitter problems that
> appear after an hour or so of flight.
> ...
> When the problem was discussed with a local avionics shop
> their analysis was that it could not be a heat related
problem
> within the audio panel because the audio panel was a
simple
> mechanical device with no electronics inside.
>
> Can anyone confirm this description of the inner workings
> and hidden mechanisms of this audio control panel?
There are electronics within the CP 136, but mic audio and
mic key are merely switched. A switch shouldn't fail if the
temp is elevated. Has your friend tried another microphone?
Reg,
Fred F.
Message 4
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--> Avionics-List message posted by: "Mike Larkin" <mlas@cox.net>
Does it happen on both radios at the same time or just one? What kind
of radios does he have in the airplane? I may have a CP 136 roaming
around here. I have worked in the avionics trade for over 15 years and
have not seen one of these units fail other then some switch problems...
Need more information before I can give you some good ideas...
Mike Larkin
-----Original Message-----
From: owner-avionics-list-server@matronics.com
[mailto:owner-avionics-list-server@matronics.com] On Behalf Of
bakerocb@cox.net
Subject: Avionics-List: NARCO Help
--> Avionics-List message posted by: <bakerocb@cox.net>
8/18/2005
Hello Avionics Experts, My friend has a Cessna 172 with a NARCO CP 136
TSO
audio control panel in it. One selects which radio to transmit on or
which
receivers to listen to by pushing in round buttons. No intercom is
incorporated.
He has been having VHF radio transmitter problems that appear after an
hour
or so of flight. Since both transmitters send out just basic carrier
with no
voice included after this failure mode happens it has been assumed that
the
failure may be heat related and caused within the audio panel since both
transmitters are affected the same way at the same time.
When the problem was discussed with a local avionics shop their analysis
was
that it could not be a heat related problem within the audio panel
because
the audio panel was a simple mechanical device with no electronics
inside.
Nevertheless their solution was to replace the audio control panel with
a
modern PS Engineering audio control panel and intercom at the cost of
big
bucks.
Can anyone confirm this description of the inner workings and hidden
mechanisms of this audio control panel? Can anyone come up with a better
(cheaper) cure than the one described above? Thank you.
OC
--
8/18/2005
--
8/18/2005
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