All the discussion about avionics has set me to thinking. I just remembered another issue: Comm 1 on my plane doesn’t hear very well. Comm 2 is just great. The avionics shop tested everything out and swapped the radios without improvement. The tech told me that it must be due to the position of the antenna. If this is the case then I’d expect other SR22’s to have the issue. Anybody out there with the problem?
The difference in reception sensitivity is quite pronounced: when ATC hands me off I’ll report in and the squelch won’t even break open. By the time I switch over to Comm 2 I’m just in time to hear a full strength repeat reply from ATC. As you would expect, distant ATIS signals are full strength on Comm 2 and unreadable on Comm 1 even after manually opening the squelch.
My workaround is to use Comm 1 as my short range unit (tower, ground, etc.) and Comm 2 as my en route radio.
I’ve never noticed this. I do have the selective transponder blanketing at certain angles though. I’d give you a demo ride, but I’m still some weeks away.
This certainly isn’t right. If it’s that weak on receive, I’d be suspicious of the antenna or wiring.
The only issue I’ve ever had is on the ground with several metal buildings between me and the tower. Sometimes they have trouble hearing me, but I’ve never had a problem on receive, nor have I had any troubles at all while airborne.
A two separate times, I’ve had a less severe version of this problem - weak reception.
In one instance, the avionics shop reset the autosquelch. While apparently not documented in the users manual, the autosquelch is apparently adjustable by the shop. If the autosquelch setting is the problem, you can partially test it by disabling the squelch (PRESS the COM volume control and autosquelch goes off). If you can then receive the station fine, it is possibly the setting of the autosquelch.
On another occassion (other radio), the avionics shop reported that there was a bad diode on the receiver, Garmin said “yeah - know about that - we have a fix”. Sent the unit back to Garmin, back in a week, works fine.
I have no comm or reception probs in my SR22, but a friend does. His problem was weak reception on #2, which when swapped with #1 stayed with the receiver. So this was not a wiring or antenna problem.
I have also heard that the Garmins are 3 just not as good (strong) as some separately boxed GPSs and navcomms. I recall the the early handheld (Garmin and King) GPS/Comms had lots of problems.
I still really like the Garmins… Now if I only had a 530!
I had the problem last evening flying from York, PA to Norfolk, Va and back. Interestingly it happened in about the same location on both legs of the trip. The plane was about in the same position relative to the station (i.e. station was either off the nose or the tail of the aircraft). I am not sure whether the antenna on the bottom of the plane is COMM 1 or 2, but it is bent, possibly shaping the antenna pattern a bit. I have this situation occur about 1% of the time. WHen I don’t get a response, I open the squelch on the radio and can usually hear the weak response on the 2nd call. When this happens, I just switch to COMM2. My guess is that it has nothing to do with the Garmins and everything to do with the antenna patterns for the top and bottom mounted antennas.
Similar symptoms but different resolution. My #2 GPS 430 was replaced last week because the avionics shop found it to have “sensitivity way below spec.” Problem was that Boeing Field ATIS was not coming through on #2 radio when #1 radio received it fine. Also, some suspicions that transmitting was okay but receiving was not.
Replacement cured the radio problem. Although, now getting the configurations on the Garmin 430 set up properly has been a bit of a challenge – someone else mentioned the maintenance setup pages that have lots of magic incantations.
Thx all for the feedback. Based upon your comments, I’ve asked CD for any advice the company may have. I’ll take another whack at getting it fixed sometime soon; perhaps when the weather isn’t so nice!
There are a large number of configuration pages in the GNS 430 that are not documented in the user manual. I observed the shop going into these pages to adjust the side tone on mine. There are at least 10 and probably more of these configuration pages and at least one of these is used to set and test various parameters of the COM portion of the GNS 430. While this won’t solve an antenna problem, I think it is worth knowing that there are a number of things that can be adjusted easily by a knowledgeable technician.
I had the problem last evening flying from York, PA to Norfolk, Va and back. Interestingly it happened in about the same location on both legs of the trip. The plane was about in the same position relative to the station (i.e. station was either off the nose or the tail of the aircraft). I am not sure whether the antenna on the bottom of the plane is COMM 1 or 2, but it is bent, possibly shaping the antenna pattern a bit. I have this situation occur about 1% of the time. WHen I don’t get a response, I open the squelch on the radio and can usually hear the weak response on the 2nd call. When this happens, I just switch to COMM2. My guess is that it has nothing to do with the Garmins and everything to do with the antenna patterns for the top and bottom mounted antennas.
FWIW,
Paul
N925PW
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Paul,
Your experience is just what I was told by the avionics technician: He said he thought the problem was the radiation pattern due to antenna-groundplane-fuselage interactions. If I recall correctly, Comm1 operates off the top antenna and Comm2 uses the bottom aerial. Now that I think it through, my problems in flight have occurred when the station in question is pretty much directly in front of me (e.g., Stockton approach en route to Stockton; destination ATIS while still 30+ miles out, etc.). Your post makes me think that I need to try receiving distant stations on Comm 1 that are located at my 9 or 3 o’clock positions.