SV-COM-C25 Com frequency switching problem

[Eric_Greenwell]

When I switch from the KRLD CTAF (122.7) to the AWOS (132.675), the AWOS is not always received immediately. It can take from several seconds to minutes before I hear it. This is annoying, but now I'm becoming  concerned it may also occur on other (or all) frequencies, and I may not be hearing CTAF transmissions, and that maybe my transmissions are not going out.

- I can often start receiving by clicking the mike for several seconds (one second doesn't seem to do it).
- this problem has occurred at other airports
- unsquelching the radio does not bring in the AWOS
- the problem happens on the ground and in the air
- none of the pilots (including me] that flew the plane the first few weeks it was in Florida can recall this problem. It was first noticed after leaving Florida, on the way to Washington State [corrected from my original remark]
- The aircraft (Phoenix U15) is new, with Skyview and the C25 com installed by Sebastian Communications in Florida.

Other issues that might be related to this:

- Using Dual Watch with CTAF/AWOS causes the AWOS to "stutter"
- I sometimes get squeals and static (chick chick chick kind of noise) on the AWOS frequency while waiting for the AWOS reception to begin, generally within a mile or two of the airport

 

[Eric_Greenwell]

Some background I should've mentioned in the first post. I'm flying a Phoenix U15 touring motorglider, so I often fly with the engine off and the propeller feathered. I leave SkyView running, mainly to keep the transponder on, so the battery voltage drops continuously during the flight from the engine-on 13.8 volts to as low as 12.0 after 3 hours.

Update: The radio worked perfectly today. I now suspect the problem might be related to the system voltage, as it seems much more likely to occur with the engine off (in the hangar, or while soaring) than it does with the engine on. Today, the voltage reported by SkyVeiw did not drop below 12.1 (even after 2.5 hours of soaring); in the past, it's been as low as 11.9 volts.

 

[dynonsupport]

Eric,
You have us a bit stumped.

The receiver on the radio is mostly analog, so there isn't really any software or other things that we have been able to theorize a behavior from. So all we have are questions:

1) Does it only happen on certain frequencies or parts of the frequency band?
2) Does it happen only when you are close or far from the station?
3) What do you hear when you manually unsquelch the audio?
4) When in dual watch, does it work if someone broadcasts on the primary frequency?
5) Does the AWOS broadcast all the time? Just asking since you mention transmitting seems to get it working.
6) Where is the antenna on the plane, and what kind of antenna is it?

A few other notes:

The transmitter is totally independent of the receiver, so it's unlikely you have an issue on both sides.

The "stutter" in the AWOS with dual watch is expected. Dual watch works by quickly jumping to the other frequency and checking it, and during that time you can't hear the standby frequency.

 

[Eric_Greenwell]

1) Does it only happen on certain frequencies or parts of the frequency band?
2) Does it happen only when you are close or far from the station?
3) What do you hear when you manually unsquelch the audio?
4) When in dual watch, does it work if someone broadcasts on the primary frequency?
5) Does the AWOS broadcast all the time? Just asking since you mention transmitting seems to get it working.
6) Where is the antenna on the plane, and what kind of antenna is it?

1) I've only tried it on the RLD AWOS, but I'll try the PSC ATIS next time I fly. I believe it happened with the Moriarty, AZ, (0E0) AWOS, but I thought it was an AWOS issue at the time, and was there for only an hour for fuel and food.
2) I've only noticed it when within 15 miles of RLD, as I've been flying very locally, getting used to using it as a glider.
3) Manually unsquelching doesn't seem to make it receive. When it is receiving the AWOS, unsquelching does allow me to hear it in the hangar when the door is closed, so it is unsquelching.
4) Dual Watch does work, but I don't remember if there was a time the AWOS wasn't being received and the primary frequency was. I'll pay more attention next time.
5) The AWOS transmits it's full message, then leaves the air (no transmission, not even carrier) for 6 seconds before repeating the message. The transmitting I mentioned was me clicking the mike button, which would transmit on the AWOS frequency.
6) It's a standard 1/4 wave external antenna on top of the fuselage behind the cockpit. It looks like this one:
http://www.aircraftspruce.com/pages/av/antenna_com/av529_ant.php

As I mentioned in my second post, it seemed to get worse during my May 10 flight while I was soaring with the engine off. At the end of the soaring portion, the Dynon reported the voltage at 12.0. I'm wondering if a low voltage might cause this problem?

About Dual Watch: I like the function, but way it works now, it's unpleasant to listen to the standby frequency, because the clicks are so loud. My MGL V6 radio (in another glider) also clicks in Dual Watch mode, but they are much softer and less annoying. I hope the clicking can be subdued on the Dynon com and retrofitted to older units.

 

[Eric_Greenwell]

2) Does it happen only when you are close or far from the station?

Yesterday, I had it happen about 30 miles out while inbound to RLD. After 30 seconds or so, I clicked the mike button 2 or 3 times, and reception resumed. I had checked it several times before and after that incident, but it worked fine those times. I tried a few times on the PSC ATIS, but did not have a problem with it.

I wonder if clicking the mike button (i.e., brief transmisisons with no audio) works because it pulses the supply voltage. Is there anyway to read the voltage the radio is getting?

 

[Eric_Greenwell]

1) Does it only happen on certain frequencies or parts of the frequency band?

I experienced the problem again today. I had Prosser (S40) AWOS and CTAF in the active and standby frequencies; the Dynon showed 12.3 volts (engine was not running).
[olist]
[*]I tried them both, and got them both, at least once.
[*]Later on, I switched to the Prosser AWOS, and it did not come in, even after a minute.
[*]I put the Richland AWOS (KRLD) in the standby frequency, switched to it, and it also did not come in, despite waiting a minute or so.
[*]I switched between them a few times with no luck.
[*]Finally, I pressed the mike button for a couple seconds with Prosser AWOS in the active frequency, and it came in. Switching to Richland AWOS - it also came in.
[*]When they do come in, they are loud and clear.
[/olist]
This is bizarre behavior, and most inconvenient when I can't get the AWOS when needed. Maybe it's time to do an exchange of radios so you can examine mine at your facility, and I can fly with one that always gets the AWOS?

 

[Eric_Greenwell]

Maybe it's time to do an exchange of radios so you can examine mine at your facility, and I can fly with one that always gets the AWOS?

That's what Dynon did, sending me a new radio that completely cured the problem, so I was able to depart on my month long trip without delay. Thanks, Dynon!

Besides the problem with not receiving the new active frequency after switching the active/standby frequency, the new radio is much more tolerant of random static from a couple ground sources near the RLD airport, and the "Dual Watch" no longer has big clicks in the audio when listening to the standby frequency. It's now the great radio I hoped it would be.

I do wish it had an easy, quickly adjustable squelch, so I don't have to listen to every airport within a 90 nm radius that uses the same frequency when I'm landing somewhere. I could set it to squelch distant transmissions, but often want to hear distant AWOS stations, or talk to other glider pilots flying far from me.

 

[Eric_Greenwell]

After some attempts to understand the problem, Dynon decided to send me a new radio that completely cured the problem, so I was able to depart on my month long trip without delay. Thanks, Dynon!

Besides the problem with not receiving the new active frequency after switching the active/standby frequency, the new radio is much more tolerant of random static from a couple ground sources near the RLD airport, and the "Dual Watch" no longer has big clicks in the audio when listening to the standby frequency. It's now the great radio I hoped it would be.

I do wish it had an easy, quickly adjustable squelch, so I don't have to listen to every airport within a 50+ nm radius that uses the same frequency when I'm landing somewhere. I could set it to squelch distant transmissions using the Skyview menu, but often want to hear distant AWOS stations, or talk to other glider pilots flying far from me.