Radio problems Icom A220 intercom noise

[ken1266]

I am part of a syndicate operating a JodelD117A. Until November 2018 it was fitted with a panel mounted Icom A200 radio which had always performed faultlessly. When new regulations dictated that we fit an 8.33 capable radio the obvious choice was the Icom A220 based on past experience with the A200 and that we could use the same cradle, so a simple installation. After fitting we ground tested the new A220 and it seemed to function OK, transmissions and reception clear and the voice activated intercom quiet until speech from either P1 or P2 headset activated the VOX.
However, when the engine RPM was advanced beyond about 1700 a high level of noise became apparent through both headsets rendering the intercom almost unusable. The noise seemed constant throughout the upper rev range and disappeared when RPM was reduced to below about 1700. We have tried seemingly every possible combination of settings within the radios menu including mic gain, mic squelch, radio squelch, hp gain etc. all to no avail. I know that other people or groups have had similar problems with The A220 radio (several posts confirm this) but nowhere have I found a definitive answer as to what causes this problem and how to fix it.
Anybody got the answer?
Thanks Ken B

[coxargus]

It seems you are not the only one - Super cub folk 'over there' don't like it

https://www.supercub.org/forum/showthre ... =icom+A220

Frank

[tnowak]

Ken,

Although I am not familiar with this particular radio it sounds like you have magneto interference being picked up.
Is the noise specific to one mag?
Are you using an external antenna? If so, is the radio coax routed away from the mag switch leads?
I presume you have a shielded harness and plugs?

Tony

[ken1266]

Thanks Tony I will check the these.
Ken B

[tr7v8]

As an ex radio tech. Try good earth on aerial ground plane, ensure power wiring is away from mags and leads. Worth trying mainline choke in the power lead to the radio. Car radio shops sell them.