SV Comm noticeably weaker than removed king KY197

[randylsnarr]

I recently installed SV Comm and intercom and removed my king comm KY197 7 watt radio and crummy softcomm intercom.

2 issues I have are the com radio is noticeably weaker than the previous radio. I understand the 197 is a 7 watt radio and Dynon is a 6 watt radio. The I used to be able to transmit 200 miles and now I am weak at 40 miles. From my wingman, he says my transmissions sound like the treble is turned up and I am. Scratchy. I sounded like an airline on my old radio according to him. I also get a crackling in the intercom from the d700 and d1000 displays. The crackling goes away when I turn off both displays. Used the same antennae and coax..
Any ideas?
Randy Snarr

 

[Carl_Froehlich]

I noted on my install that the default mic gain setting was much too low. Increasing it made the Dynon radio work just like the Garmin (Comm #1). The instructions tell you how to change the mic gain.
Carl

 

[randylsnarr]

I did this and it has seemed to help.
Thank you for the feedback.
Randy

 

[bruceh]

What are you setting the mic gain to?
If I recall, the default is 5%.

 

[randylsnarr]

After speaking to Dynon support, I moved the mic gain up from the default to 50. Seemed to help a little. Also, i recently have had intermittent issues with not being able to transmit at all. I had the com tested and it was good. I am working to determine if I have a cabling or antenna issue.

Can someone recommend a good antenna for a composit non carbon airplane. I need an antenna that can be bonded to the inside of the tail cone.

I will reply back once I determine the issue with the cable/ antenna.
Thx!
Randy Snarr

 

[bruceh]

I erred in my previous statement about the default mic gain being 5%. It is actually 50% in the COM menu. The sidetone is 5%.

I did bump up the mic gain to 70% and flew today. No improvement. I did notice after updating to SV 10.1 that there was some instructions given on the menu about setting the mic gain with the engine on to get a good baseline. I will try that next.

I'm still a bit frustrated in the ability of the COM to reliably transmit. I can do a radio check on the ground with the tower and other frequencies and it all sounds great. As soon as I fire up the engine I can barely be heard on just a few frequencies.
What else could be causing this to happen? Electrical interference of some sort when the engine is running?

 

[dynonsupport]

Bruce,
Are you 100% sure that it is the engine running, or is it other systems that come on line as part of your engine start?

 

[bruceh]

I have tried a number of things, but yesterday I did a radio check with Ground on 121.65. Loud and clear with the engine off. Start the engine. Nothing else electrical changed. Try to talk to Ground again, and nothing. I can get the Tower on 119.875, but nothing on the ground frequency. The tower guys are always telling me that my radio is barely readable when the engine is on, but always "loud and clear" when I do a radio check without the engine on.

I can hear everything just fine, but spotty transmitting. I have even swapped out the antenna with no change.

I'm open to any suggestions on what to try next.

 

[60av8tor]

Probably not your issue, but thought I'd share just the same. I recently had the SV radio and intercom installed. One day, during taxi, I was getting the same response from tower - weak, barely readable, etc. Several days prior, I had turned some avionics off while messing with some items in the hangar. I had forgotten to turn on my intercom - sounded no different in my headset talking on the radio, but obviously had an affect on my transmission. I did not wire the added SV components, so I do not pretend to understand how they relate, just thought it may be a component of your issue.

 

[bruceh]

Flew again today, this time both Ground and Tower frequencies were basically unreadable. No difference with engine on or off. Off to the radio shop next to see what they can find.

 

[60av8tor]

Bruce - any resolution with this? I'm having similar issues - intermittent poor transmission quality - and I'm not sure where to start.

 

[dynonsupport]

Jon,
Give tech support a call or email, we likely have a resolution for you.

 

[60av8tor]

Jon,
Give tech support a call or email, we likely have a resolution for you.

Will do, thanks.

 

[randylsnarr]

Had the radio and antenna tested. The avionics shop told me my antenna was very poor. We plugged in a test antenna and new cable and the power output was much better..

The antenna that now tests bad is a ribbon antenna buried in the vertical stab. Not sure why it worked without issue with my KY197. I tried a Dave Archer antenna in the tail cone but it has very poor performance. It also messes up the ADHARS that is in about 20" away..

Any ideas on an antennae that performs decently that is small. An internal antennae is preferred..
I may have to go to an external comm antenna like a bent Commant style.
Any suggestions would be greatly appreciated..

Thanks!
Randy Snarr
Lancair 235/320
N694RS

 

[cessnadriver850]

You might look into the advance aircraft electronics mdl 5I or 5T. Aircraft Spruce pn 11-04261 and 11-04262. I have one attached to my bench for testing.

 

[randylsnarr]

Weak Com Radio update.

Sorry for the delayed Response..

After trying several antennas, I finally had a local shop who is a Dynon dealer test the radio again.
The radio would measure about 6 watts when plugged directly to the test set. When we connected a good antenna and tested again, the power dropped down to .06 watts..
In short, the radio tested good until we put it under load with an antenna.
I have the replacement radio installed and am experiencing much better performance..
Randy Snarr
Lancair 235/320
N694RS

 

[60av8tor]

Thanks for the update, Randy. Mine is back to Dynon for the second time :-? Paid $100 to overnight it the first time. My choice to do so as I had an upcoming trip planned and really wanted a second radio for the trip, but stings a bit when it comes back with the same issues. Here's hoping I have a radio that does more than receive the second time. I really enjoy the integration, but thus far have been a bit disappointed with the fits I've been having.

 

[randylsnarr]

Re: crackling in Bose ANR headphones update

I have had crackling in my Bose ANR headsets since I installed my SV mode S transponder. I have found this noise in the headsets even when they are not connected to the airplane.
I have been reading online about other ANR headset users getting crackling with the new mode S transponders..

One stated solution was to go to a mode S specific antenna.
I admit I am currently using a cheap antenna I bought from Spruce.

I will post my findings once I have a new antenna installed.

Randy Snarr
Lancair 235/320
N694RS

 

[MCRider]

@Randy:

I have done some measurements (with a vector network analyzer) with several transponder antennas. They all seem to work very well - VSWR was always better than 1.2. There are no mode S specific antennas. The frequencies have not changed with mode S. The signal is different of course.

I would rather look for grounding (electrical contact, size of ground plane if aircraft skin is not metal) and/or cabling including connectors.

MCRider

 

[dynonsupport]

Randy,
As MCRider says, the "cheap" antennas are fine, and there is no such thing as a Mode-S antenna. The frequencies are all the same, which is all an antenna cares about.

The first place we see this issue is when RG-58 is used instead of RG-400. RG-400 is double shielded, which prevents a lot of energy from leaking out the coax. RG-58 is single shielded and leaks a lot. Given a transponder is 300+ watts, this matters. This is the #1 cause of noise from the transponder.

If you have quality coax (and it's not broken), then the next thing is bad grounds. If your antenna ground plane is not big enough, or the antenna is poorly connected to it, you'll get a lot of energy coming out of the coax too.

Start with those, not an antenna replacement in our opinion.