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By Spooky
Good afternoon all!

As part of the enforced 8.33 upgrade I decided to buy an Icom A6E as it should be a straight replacement for the A3 and work without issue. Unfortunately it doesn’t :x

The A3 works without issue whether running on its own battery or via the aircraft power.

The A6E has a high pitched “whine” when it transmits. This happens whether on the mains, on the rechargeable battery or AA batteries. There’s no excess noise when receiving.

Any ideas on what might be causing it? It operates through a Lynx interface and transmissions are made via a PTT on the control stick and headsets are Microavionics.

Thanks in advance
From what I've seen and read about, that 'whine' seems to be often caused by a ground loop. If you Google 'ground loop isolator' you'll find you can buy really quite cheap solutions to the problem.

I assume the radio transmission is fine if you use it as a 'walkie-talkie'. If this is the case and you only get the whine when YOU transmit, then it suggests the ground loop is in your PTT circuit.
Don't think it is a ground loop. There are well publicised issues with the new ICOM range when it first came out. When using a headset adaptors there was a whine on transmit. Don't have time now, but there was a long thread on the issue in this forum.

IIRC ICOM did nothing and would not acknowledge the issue. This is why the Vertex range of radios suddenly became the radio of choice ( they are cheaper as well).
Keef, late of this forum, I think had a fix where ferrite beads were added, possibly with a mod to the wiring.

Do a search, but it will be about 4 years ago, possibly more.
PaulSS, Spooky liked this
Cheers for the responses. I wrote to Icom and they sent me this response.

“Your description of the problem is indicative of RF feed-back occurring, this is when radiated power from the
aerial is absorbed by the headset/headset cable/intercom circuit, and forms a feed-back loop into the mic amp of the radio.

Preventative measures include:
Trying different headsets, some are more sensitive than others.
keeping the headset and cables as far away from the aerial as possible.
Routing any cables away from the radio aerial at 90 degrees.
Using an external (aircraft mounted) aerial , fed by 50 ohm co-ax, rather than the set top helical.
Fit ferrite clamps to the headset lead, mount one on the cable near the ear-cups, and the other on the cable near the radio.

If all the above fails to help, I can perform an unofficial modification to your radio that reduces its sensitivity to RF feed-back. “

So I’m trying the ferrite clamps (arrived today) and will update on how that goes.

I felt sorry for the chaps in the tower, probably thought they were under a sonic attack!
I had this issue with my backup A24 and DC ANR headset using the Icom supplied headset adapter. I resolved it by using a battery 2-place intercom as no amount of pfaffing with ferrites or cable positioning would resolve it.

It seems the audio side of the radio is susceptible to induced RF, which is pretty rubbish for a fairly expensive radio. However my new A6 with the 8.33 software doesn’t appear to suffer, although this could be down to having swapped to a Lightspeed PFX headset.

IIRC it DID transmit some noise which was clearly being picked up my the mic side.
Ian Melville wrote:Can you send it back? Not fit for purpose.

I’ll try, the problem is that I bought it back in November :?
Worst case, it works fine as a handheld without the headset so could be useful at airshows etc

I’ve ordered a Yaesu 550L rather than having the Icom modified. I tried my friend’s 450 yesterday and that had no issues :thumleft: