I have a very strange issue that causes interference on radio communications. A broadcasting station is nearly unreadable at times but is better when going away from the station that when approaching. It is clearly “noise” being generated by the aircraft but how do I find the cause and then able to resolve? I need a very experienced person to do this so any recommendation for the UK please. BTW most usual sources such as generator, magnetos have been eliminated.
Thanks
What radio and intercom do you have fitted ?
Probably the best radio engineer in the UK is to be found on these pages under the name of wigglyamp.
Is this only during flight, only with engine running, or with engine not running?
What does it sound like?
Is it this?
I also solved a weird static-like problem by bonding across the elevator bearings. They were greased “too well” and the static was arcing across them, on its way to the static wicks on the elevator. Running some braid across them solved it. The problem was worse on COM2, whose antenna was nearer the tail.
I know of only one smart avionics guy anywhere and I think he’s more or less retired (@wigglyamp). Haha posts crossed with A&C 
Peter that is really rather like the interference I have. The nav comms are Garmin GNC 255 and I dont know what the intercom is. Hope this may help someone.
When you have this interference , do you have a RX on the display , if so ,what com softw level does your GNC have ?
In 2017 there was a softw update for a better adjustable squelch .
Com softw 2.30
If not try if switching of the radio ‘s kills the interference , if not switch of the intercom to see if that’s kills the interference .
Another thing to try is switching of the alternator for a moment to see if the problem is coming from the alternator
Definitely not alternator, tested for that, and mags as well. Yes have RX on the display. I will check what software is currently installed. Apologies but i dont understand “switching off the radios”. If I do that then nor radio traffic equals no sound and no interference. What am I missing? The interference is only there form a broadcasting station.
thanks
Fenland
Someone it is the intercom wiring that picks up the interference and transmits it via he audio system so the suggestion is not as daft as it might first sound. But it sounds like your intercom is using the system built into the Garmin Radio.
Is the interference from the broadcasting station (by broadcasting station, I assume you mean FM radio in the 88-108 MHz band) or are you trying to listen to the broadcasting station? Your first message makes it sound like you want to listen to the broadcasting station but can’t due to interference, and a later message makes it sound like you’re suffering interference from a broadcasting station, and then something about it being local aircraft interference.
If it’s bleedover from a nearby FM broadcast transmitter (broadcast FM transmits with quite a lot of power) affecting you at an airfield nearby the transmitter (bleeding through or desensing your aircraft radio), you may need to look into filtering the offending broadcast. If you’re flying a certified aircraft, I’m not sure what’s available to you but if you’ve got a permit aircraft you can probably get help from your nearest amateur radio club.
What frequencies are being affected?
Where’s your antenna sited? You may have a radiation pattern null in front of your aircraft, which will decrease signal-to-noise ratio for receiving when the transmitting site is in front of you (I have this issue when Ronaldsway are using their Snaefell transmitter site, since the antenna at least for a short time is either level or above the aircraft and in front of it, the engine causes a null in my antenna radiation pattern in that direction and it’s sufficiently annoying I’m considering relocating my aircraft antenna).
All good questions Alioth – I was referring to ATC or other aircraft transmissions and nothing to do with anything else. All frequencies are affected. Both antenna are on the cabin roof and have not been disturbed. Jetprop (thank you) has prompted me to research and in so doing I find there are 3 outstanding software updates. I presume these need an engineer to install?
Thanks to all.
