Posted by: Darren
on Apr 30, 2009
You may have heard me mention in the Barton Microlight Fly Out that I was subjected to an earful of awful noise/interference through my headset during the whole of the trip. My initial reaction was that my brand new Micro Avionics top of the range helmet was at fault. I had tested the intercom and radio the week prior, but not in flight. The moment I strapped myself into the seat on that Sunday morning and turned on the radio and started up, I though oh Cr**p, as the hissing and humming came through my headset. I thought for a split second of jumping out and swapping over to my Lynx helmet, but there was no time, we were off on our jolly to Shobdon and Caernarfon.
Some of the lads on the trip thought it might be the GPS and we talked of power leads being too close to the radio aerial etc. So the weekend after I was back down at Barton to investigate. What I found was quite intriguing, the problem did appear to be associated with the Garmin 296 GPS, which I have panel mounted. With my ICOM A6E radio connected, every time I connected the external GPS antenna to the Garmin I got a load of interference/noise through the radio. The question was, is it the GPS, radio or external antenna at fault? Wayne lent me his radio and the same happened with his older ICOM, so I concluded it was either the Garmin or external antenna.
What was needed now was someone else’s GPS to check. I went down to Barton yesterday 29th April to have a chat with Mark Jackson, if anyone would know the ‘Microlight Oracle’ would! Mark advised me that it would be down to the wiring and gave umpteen examples of weird happenings with radio and GPS and even how the new Enigma ‘glassy’ cockpit/engine management system available on the new Quik R, had succumb to interference problems.
Mark, kindly equipped with his Garmin 296 and an older ICOM radio proceeded to my machine. I plugged in the radio and left out the intercom leads and plugged in the external antenna to my GPS. For a split second I felt an idiot as there was no noise, before realising I hadn’t turned on the GPS. Voila! GPS on and noise was emitted from ones radio. With a few buttons pressed and the Squelch turned past 15, the noise disappeared. Oh what a plonker, I felt and oh what a plonker Mark must have thought!
Anyhow I am somewhat delighted that the £477 I spent on new helmet was not wasted and that I don’t have to consider replacing GPS, its antenna or my radio. There’s always a moral or something to be learnt and this little story is no exception. Our perceptions of faults all too often lead us to expecting the worst as we jump to conclusions, but even when I narrowed down the search and found the issue to be with the GPS and external antenna, I was too quick to be contemplating a major replacement, when all that was required was the twist of a knob; which truly left me feeling like one!