Jesse
Well Known Member
We are having a problem that I wanted to post here to see if anybody here has a valuable suggestion. In a new RV-10 with a professional audio harness (Approach Fast Stack), we are having problem with receive range on our radios. We have a GMA245 audio panel, a Dynon Com (Trig Transceiver) and a GTN650. This has been an ongoing problem that didn't appear at first, but became noticeable around 10-15 hours from new.
On a test the other day, the plane left here. From our base station radio with an antenna on the top of the hangar, we had great reception for the first couple of miles. The further he got away, the more weak and staticy the plane received, although the transmit was still loud and clear. When the plane was 15 miles away, he could not receive the base station at all, and he was still loud and clear receiving at the base station. In summary, his receive range is very short, but transmit seems to be good, or at least better. This problem is with both radios.
We have verified that we have good coax from both radios. to their respective antennas, which are the RAMI AV-17's, and the coax run down opposite sides of the plane to their respective antennas. Both antennas were new when installed and bought together. We removed some paint where the screws attach the antenna to the airplane, and used lock washers under the nuts after removing primer from where the nuts tighten down, so we know we have a good ground (the antennas are under the pilot and copilot seats). We have tested with each radio powered down and the problem is still with the powered radio, so it isn't cross-talk. We have verified, and added, a good ground from the audio panel to the airframe. We have tried with both pilot and copilot headset alone, with an without the rear headsets, and have tried other known good headsets. We have replaced the Dynon transceiver 2 or 3 times, thinking it was specific to that radio, with no change. The intercom works just fine all the way around. We have swapped with another GMA245 audio panel and there was no change, so it's not a bad audio panel.
The only thing we can think of that is left to check is to replace one or both of the COM antennas. I have never had a bad RAMI bent whip antenna, certainly not out of the box, and the likelihood of two at the same time on the same plane seems even more unlikely, unless they were both from the same batch that happened to be a bad batch, but I don't know how we would change that.
As a side note, this plane has the full EFII system with the buss manager. We are going to test reception range on the ground with the engine on and off soon to see if the engine could be causing any disruption.
Any thoughts?
On a test the other day, the plane left here. From our base station radio with an antenna on the top of the hangar, we had great reception for the first couple of miles. The further he got away, the more weak and staticy the plane received, although the transmit was still loud and clear. When the plane was 15 miles away, he could not receive the base station at all, and he was still loud and clear receiving at the base station. In summary, his receive range is very short, but transmit seems to be good, or at least better. This problem is with both radios.
We have verified that we have good coax from both radios. to their respective antennas, which are the RAMI AV-17's, and the coax run down opposite sides of the plane to their respective antennas. Both antennas were new when installed and bought together. We removed some paint where the screws attach the antenna to the airplane, and used lock washers under the nuts after removing primer from where the nuts tighten down, so we know we have a good ground (the antennas are under the pilot and copilot seats). We have tested with each radio powered down and the problem is still with the powered radio, so it isn't cross-talk. We have verified, and added, a good ground from the audio panel to the airframe. We have tried with both pilot and copilot headset alone, with an without the rear headsets, and have tried other known good headsets. We have replaced the Dynon transceiver 2 or 3 times, thinking it was specific to that radio, with no change. The intercom works just fine all the way around. We have swapped with another GMA245 audio panel and there was no change, so it's not a bad audio panel.
The only thing we can think of that is left to check is to replace one or both of the COM antennas. I have never had a bad RAMI bent whip antenna, certainly not out of the box, and the likelihood of two at the same time on the same plane seems even more unlikely, unless they were both from the same batch that happened to be a bad batch, but I don't know how we would change that.
As a side note, this plane has the full EFII system with the buss manager. We are going to test reception range on the ground with the engine on and off soon to see if the engine could be causing any disruption.
Any thoughts?