There is a problem with my two VHF radios.

On both radios I get the squelch static breaking through when there isn’t a transmission.

However everything is fine before the engine is started.

Given this, it must be something to do with the ignition system when it is powered up and running the engine.

I found a guy online with the same radio, a Garmin GTR20 and a Garmin G3X as I have. I did try turning up the squelch suppression all the way of both radios. The GTR remains unusable but the radio in the GTN750Xi can be used with only the occasional static break through.

The online solution was special spark plug leads that suppress electrical noise. It worked perfectly for him after that.

I got in touch with EFII System 32 support and bought the same leads at huge expense. I think they are available here a tenth the price but I wanted to be 100% sure I had the solution. Yes its those light blue leads in the pictures.

Unfortunately, zero change with the radios. I still have the problem exactly as I did before all this work. I had two very unpleasant days crawling around the engine, removing the radiators from their mounts just trying to get the eight leads in place. I did one at a time to be sure they were all going in the right place. I couldn’t even see where the wires were going at times and just felt my way around. I was super careful with the lengths of the leads and crimping them correctly. Let me know if you need this done. hahaha It will be expensive!

Job done, but it didn’t fix the radio issue. At least the engine still runs so the leads are proven to be in the right place.  So its back to EFII support and online to try and find a solution.

The next try was the antenna cable.

I went for RG142 rather than RG400. The specs were similar but there is slightly less physical shielding on the RG400. I probably should have gone for that in the first place but it was a little weight saving and I used about 15 meters of the stuff.

I hooked up some RG400 to the wing connection and back to Com2 in the G3X/GTR20 which is the worst of the two radios. I then pushed the plane outside and started the engine. Zero change in the noise problem. <sigh>

As an aside, I had to take the canard off to get to the radio connection. You can see I labelled ‘not safe’. I tend to do this as a habit so if things are not done up ready for flight, I won’t forget to attend to it.

So it was back to Robert Paisley at EFII. He wants to see where and how we have the earths setup on the plane. This may be the problem, the dreaded earth loop. At least we have eliminated ignition leads and antenna wiring. See, I can look on the bright side.