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SV-Comm Issues

engineerorange

Well Known Member
I have a SV-Comm, Dynon intercom and Delta Pop bent whip antenna on the belly.
In December when my plane first flew, radio transmissions were very broken on all frequencies. Parts of transmissions were fine, some words came through clear, some not at all, but the carrier was always present. Dynon said this is a known issue and had me clean the radio mounting points and add a ground wire from the case of the intercom to the case of the radio. This made zero difference. At that point, I suspected my antenna or installation so I hooked a handheld directly to the coax that I unplugged from the back of the radio and got 5x5 transmissions. I let Dynon know and they sent me a new radio. When the new radio arrived, I installed it and got carrier only, no sound at all. At that point, I suspected my antenna or installation again so I attached a mag mount antenna to the radio with a patch cable. I got good transmissions on the ground pointing me to my antenna or installation again. I made a new coax and temporarily installed it between the radio and antenna. I got good transmissions on the ground at that point, so I routed the coax permanently and tested again by talking to planes in the traffic pattern from the hangar. Problem solved I thought. A few days later it was time to go flying, and we again got very broken and weak transmissions on unicom(122.7). We tried a few different frequencies on the ground and found that we could communicate on some frequencies better than unicom and the test pilot took off for more testing. Once in the air he was able to talk to a control tower(128.15) about 12 miles away and they reported 5x5. He contacted ATC on 125.15 and they reported 4x5 with some background noise that made him sound like he was flying a helicopter. Air to ground on 123.45 was OK from some locations and not good from others. Back to unicom for landing and got carrier only.

At this point I got frustrated and decided it had to be the antenna, as that is the only thing that hadn't been replaced. So I called Don and he agreed to send me a new one, even though neither of us really thought it could be the issue since some frequencies worked fine. Today I installed the new antenna and guess what, same ****. So now the radio has been replaced, the antenna has been replaced and the coax has been replaced. Either I am capable of building an airplane including all the avionics wiring, engine building and air frame construction but can't install a radio, or I am the unluckiest person in the world and got 2 bad radios in a row.

Does anybody have any ideas or are these Dynon comms just junk? I have a Dynon handheld and it works great.

Thanks for any help,

engineerorange
 
I had similar experience with an SV-Comm installed in an experimental Super Cub with a Skyview classic. I went through the same iterations with coax, antenna, ground plane, unit swap out, Dynon supplied notch filters etc.... Dynon determined my serial number was an early model and even swapped it for a newer unit.

In my case I concluded that the SV-Comm (even the newer s/n) had glitches with transmit or recieve on certain frequencies right next to solid performances frequencies. I found other EAB aircraft owners with similar experiences both here on VAF and other user groups. I like Dynon and it pains me to say. But in certain installations the SV-Comm may not be quite ready for prime time. And the same level of frustration found by the owners has to be felt by Dynon. More so because the Dynon support reps can't control or be sure the airframe specific installation was done well meaning that some real boondoggled installations taint the problem. I build and install panels and avionics (privately for myself and friends) and haven't had to jump through as many airframe install hoops with other comm units as I did with the Dynon SV-Comm. Even with my audio nemesis the MGL V10 (software setup issues).

Since my experience 18 months ago I have avoided the SV-Comm and haven't returned, with subsequent trouble free installs with other comm units.

I am confident Dynon is capable of and may have already improved the SV-Comm frequency issues. I can't afford to be a beta test case and will reserve verdict until I have proof positive the SV-Comm performs as advertised.

I am an equal proponent of Skyview and G3X but there is no question the Big G remote LRU comm products just seem to work right out of the box. As do non-remote units from the likes of Trig, Icom, Garmin, Becker, King etc...

Just one guy's experience here.

Jim
 
Has anybody experienced this issue and solved it? I really don't want to buy another radio since I paid good money for this one and like the integration with the skyview. At this point it is really holding up phase one when each test/change takes over a week due to waiting on response/parts/etc.
 
I had early SVcom issues. They were different than yours though. I originally wired it to my avionics bus along with a G430W and a PS Eng Audx. The SVCom wouldn’t always boot up after engine start.
I ended up moving the power to the unit from the avionics bus to the SkyView bus and the problem went away. For 4 years and 400+ hours it has had crystal clear RX/TX on all frequencies and I love its integration into the system.
 
I had early SVcom issues. They were different than yours though. I originally wired it to my avionics bus along with a G430W and a PS Eng Audx. The SVCom wouldn?t always boot up after engine start.
I ended up moving the power to the unit from the avionics bus to the SkyView bus and the problem went away. For 4 years and 400+ hours it has had crystal clear RX/TX on all frequencies and I love its integration into the system.

What kind of antenna do you have and where is it mounted?
 
I was having similar issues like you and transmissions really weak on some frequencies. Dynon replaced radio with no effect. Tried 3 different coax cables. Problem not fixed until I replaced my Delta pop antenna with a Comant antenna. High SWRs went away and all ok now. Have you put a SWR meter on you antenna line to see if high SWRs are causing your problem?
 
I was having similar issues like you and transmissions really weak on some frequencies. Dynon replaced radio with no effect. Tried 3 different coax cables. Problem not fixed until I replaced my Delta pop antenna with a Comant antenna. High SWRs went away and all ok now. Have you put a SWR meter on you antenna line to see if high SWRs are causing your problem?

I did use an swr meter in my troubleshooting. It showed good once I replaced the coax, I haven't had access to the meter since replacing the antenna again.
 
I was having similar issues like you and transmissions really weak on some frequencies. Dynon replaced radio with no effect. Tried 3 different coax cables. Problem not fixed until I replaced my Delta pop antenna with a Comant antenna. High SWRs went away and all ok now. Have you put a SWR meter on you antenna line to see if high SWRs are causing your problem?

Did you test your delta pop antenna with another radio? Mine worked fine with a handheld. i can't wrap my head around what could be wrong with the antenna that it would work with another radio but not with dynon. Did you send it back to Don for evaluation?
 
Did you test your delta pop antenna with another radio? Mine worked fine with a handheld. i can't wrap my head around what could be wrong with the antenna that it would work with another radio but not with dynon. Did you send it back to Don for evaluation?

No but I will do it. I don?t know if anything is wrong with the antenna other than I couldn?t get good grounding through it to get the SWR down. On my RV-6a, it just didn?t work. I havent sent it back to Don yet. I used star washers on the studs. Don?t know what else I could do. I encourage you to check for high SWR to eliminate that as a probable cause.
 
Tower complained of weak/broken for my SV radio until I switched from Halo to Bose A20. All good now. The Halo picked up too much engine noise (straight pipes).
 
Same Issues

I have had very similar experiences as many on this thread and the OP. I have the Skyview Classic suite, Delta Pop comm antenna, Zulu 2 headsets and built a 2016 Rans S-20 Raven. Weak/scratchy transmissions on the ground as well as similar reports in the air on certain frequencies mostly at lower altitudes. 130 hours and 18 months on the plane and have been through a great deal of trouble shooting. Bigger ground plane, grounding the intercom to the remote comm checking the stamps on the unit to ensure the latest version, sending the unit to Dynon and bench testing etc. Next step is connecting an SWR bridge between the coax and comm unit.

Love the plane and the Skyview but this has been very frustrating not being able to communicate with ground control, tower or unicoms. They are also frustrated as well. The apprehension of not knowing on what frequency the problem will rear its ugly head is getting old . Hoping for answers.

Jim
 
Issue solved

I just wanted to update this in case it ever comes back up for someone else. After swapping antennae, swapping comms, msking new coax all several times to no avail, the last thing I did was make a new coax with soldered center pins and I have had no issues since. I can't explain why crimped center pins worked with other radios and other antennae and not the dynon, but that is the only thing that changed from crappy radio performance to great performance.
 
who woulda thunk??

I just wanted to update this in case it ever comes back up for someone else. After swapping antennae, swapping comms, msking new coax all several times to no avail, the last thing I did was make a new coax with soldered center pins and I have had no issues since. I can't explain why crimped center pins worked with other radios and other antennae and not the dynon, but that is the only thing that changed from crappy radio performance to great performance.

Interesting . . . how did you come on this solution? Luck? ( Luck is good BTW)
 
Interesting . . . how did you come on this solution? Luck? ( Luck is good BTW)

I tried it out of frustration. It was all I could think of. Still don't understand how the crimped connections worked perfectly with a handheld in the exact same coax and antenna installation and the dynon didn't, but it's working now.
 
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