Becker AR4201 Radio Transmission Problem

RMM

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Apr 26, 2014, 6:11:06 AM4/26/14

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Just purchased a used aircraft with a 5 year old Becker AR4201 radio that seems to work normally BUT no sound goes out on transmission. Previous owner says everything was fine prior to my purchase of the aircraft. No changes made. I am using the previous owner's Bose headsets. So I can understand the wiring was done correctly on initial installation.

The PTT click can be heard on the hand held radio opening the frequency, but no sound of the voice transmission is transmitted to the receiving handheld radio. Black triangle on top row shows the radio is transmitting. But no voice is coming through. Tried two different working headsets, one is a friends and is brand new. Same situation.

All functions on screen are normal. No error codes. Receives transmissions from the handheld radio and also receives the ATIS loud and clear.

What am I missing?

RMM

TravisBrown73

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Apr 26, 2014, 12:22:53 PM4/26/14

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I don't know a lot about radios, at all, but my 4201 manual stated clearly that the transmit button should not be depressed if the antenna wasn't connected. Something about burning out the 'transmit amplifier' or something similar-sounding. Could that have been done? That statement was recently affirmed through a discussion with a fellow pilot in our club that had done just that on accident. He had to send it back to the factory for repair.
~Travis

RMM

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Apr 26, 2014, 12:48:57 PM4/26/14

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Thanks Travis..
Antenna was always connected when we had the unit powered up. So no chance of the PTT being depressed without the antenna being connected. I did not see that warning in my reading of the manual though. We did attach a new connector on the antenna cable at the radio end. But the ground at the connector was checked before attempting the use the radio. The antenna receives fine, as mentioned. So that does not seem to be the issue. Your response is much appreciated. Thanks
RMM

TravisBrown73

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Apr 26, 2014, 1:22:01 PM4/26/14

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Ah. Right you are, Sir.
I checked my 'hardware' section of my aircraft's documentation, and see that I was thinking of this: "Dummies Guide to Aircraft Antennas" hosted at Cumulus-Soaring.
https://www.cumulus-soaring.com/xcom/XCOM%20Aerial%20Dummies%20Guide.pdf

Lots of good info for me in there, including that bit about the antenna being connected (and in reasonable tune) prior to depressing the PTT. Don't know why he had to call me a 'dummy,' though. :-)
~Travis

darrylr

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Apr 26, 2014, 1:48:35 PM4/26/14

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On Saturday, April 26, 2014 3:11:06 AM UTC-7, RMM wrote:

It receives distant aircraft transmissions OK? Then the antenna is likely connected.

Wire a test microphone directly to the rear inputs of the radio and try that.

That does not work then send it off to Becker for repair.

RMM

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Apr 26, 2014, 2:10:39 PM4/26/14

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The radio uses a harness and has a Sigtronics 200S dual intercom installed.
Harness is here...
http://www.aircraftspruce.com/catalog/avpages/ar4201harness.php
Sigtronics intercom is here...
http://www.sigtronics.com/pdf/air_pdf/Sport200S_E_INST.pdf
Where and how do you suggest wiring in the test microphone?
What type of microphone is suitable?

Thanks

150flivver

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Apr 26, 2014, 8:32:02 PM4/26/14

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Similar problem turned out to be something called the modulator. Keying the mike only resulted in "click" noise being transmitted. I clearly could hear ATC saying they could hear the click but were not receiving any voice transmission from me. Cost a couple hundred to fix.

RMM

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Apr 26, 2014, 10:50:09 PM4/26/14

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Thanks..
I will check the connections more closely tomorrow and if they look good, then Seems the unit must go to Becker in Florida.

Darryl Ramm

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Apr 27, 2014, 12:16:27 PM4/27/14

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Everything you need to know is in the install documentation for the radio.
If it is not clear what to do from that you need to find somebody to help
you.

It is precisely all the mic side of the wiring harness and intercom crap
you want to bypass in your test.

Darryl

RMM

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Apr 27, 2014, 6:12:58 PM4/27/14

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My friend is an engine guy and a ham radio operator, but not an electronics tech. The aircraft is E-AB and I am trying to learn this stuff.

Seems if the D-Sub is disconnected the whole system goes down. I am unsure how to proceed.

If you could, please give a short description of the method used to do this. I can read the pin diagram and wiring diagrams. What type of procedure and gadgets do this kind of work.

Thanks
RMM

RMM

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Apr 27, 2014, 11:09:31 PM4/27/14

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Today, after curing a ground problem with the antenna end connector, we were able to transmit on frequencies from 127 to 136. So we know the wiring is ok, but the radio won't transmit from 118 to just below 127. According to another case, the radio is not at fault and the solution is to upgrade the cable and re-crimp. So this will be the next step.

Any suggestions are welcome.
RMM

RMM

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Apr 28, 2014, 3:59:24 AM4/28/14

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Late this afternoon, we substituted with another antenna that is proven to be fully working. The same condition resulted. Below 127, the radio opens the transmission channel (the PTT click is audible and the radio displays a black triangle indicating transmission) but carries no voice. Above 127, transmission is fine. This leaves the radio as the place with a faulty part. Will call Becker first thing on Monday morning.
RMM