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MGL Radio TX riddle

rph142

rph142

Well Known Member
So I replaced my MGL V10 comm with a MGL V6 comm and now i cant transmit clearly on CTAF or Unicom, but I can transmit clearly at towered airports. When transmitting at ctaf my voice is broken and garbled and virtually unreadable. The towered field I fly out of hears me fine...:confused:. I am using the same headset, ground location, antenna/cable, etc that I used on my V10. The only difference is that the shielded PTT cable ends about 3 feet before it gets to the PTT switch. The last 3 feet is just unshielded wire. I am going to fix this next, but if that is causing tx issues, then why not at towered fields? I am seriously confused.
 
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Not familiar with MGL radios but........

Normally PTT connection is simply a grounding circuit and carries no signal.
They do not need to be shielded.

I would check your antenna connections. Sometimes you can have a problem with VSWR at certain frequencies.
 
Are you saying that transmitting on say 118.1 MHz gets you good reports, but transmitting on 122.8 MHz gets you reports of 'garbled', from other aircraft that are at least 1/4 mile away? If that is correct it is most likely an internal problem with the radio.
Can you list the good and bad frequencies? After all, after the tower closes the ctaf is the tower frequency, usually.
 
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119.7 and 118.1 are clear for me. Nut tree's 122.7, rio vistas 122.725, and Byron's 123.05 are garbled. I didn't think about frequency levels because they are all programmed into the radio. I'll swap out the antenna cable later this week for good measure.
 
Glad you posted:

V6 MGL

119.xx is garbled. 120.0- 131.xx clear as a any radio. 132.xx unreadable. 133.xx and up is crystal clear.

Listening is always clear. My transmissions on the listed freqs are unusable.

Scott
 
A quick update for everyone. I installed a new RG400 antenna cable and performed a more thorough test. My transmissions are crystal clear on all frequencies except 121.xx, 122.xx and 123.xx. Transmissions on those frequencies are essentially unreadable. I'm in communication with MGL and will hopefully have a solution soon.
 
They are a poorly done software-defined radio. This is what I have been told by someone who has reverse-engineered it. So having some frequencies where the transmitter performance is poor is to be expected with that type of design.
 
I must be lucky then because I'm building harness for my 3rd MGL radio now. Perfect function so far and my other V6 is the nicest sounding intercom and radio I've ever heard.
 
So far my V6 radio has worked perfect too. Would recommend it to a anyone. Their wiring harness was a breeze to install.
Jack
 
I've put one in my Emeraude with the fast stack harness. Good harness but too much wire for what I needed. I think the harness weighed twice what the radio weighs.
 
Some airports have better radios than others. I suspect the towered airport you're speaking of just has a better radio than the installed radios listening to you on CTAF.

Check your VSWR. I'm betting that's where you'll start to find the solution to your problem.
 
I thought I was having all kinds of problems transmitting and receiving on my V6 when I installed it two years ago. It turned out that the issue was all in the antenna. I tested the antenna and found it to be worthless. Sent it back to rami for exchange and no more problems.

Although, I am considering selling my V6 only to install a dynon com only to have more interface features with my skyview.
 
When you solve the transmit problem, please post the results. I too have problems transmitting on 121.xx, 122.xx, and 123.xx on my Garmin SL-40 radio with SPA-400 intercom. The -40 receives well but when I depress the transmit button on the stick, left or right, the transmit symbol flashes off and on, which is audible in the headset. Other radios hear it as clicking. I originally had a factory RG-58 pigtail with a short length of RG-400 coupled in. I replaced the two pieces of cable with a single length of RG-400 from back of radio to antenna, a Commant CI-122. Now when the tx button is depressed, the TX symbol is steady but I get feed back in the head set and other radios report barely readable with noise in the background. I plan to have the avionics shop test the SWR tomorrow. Thanks for any others suggestions not already mentioned in advance, Dan
 
I thought about changing out the antenna, but it worked flawlessly with my V10. The fact that everything worked so well with the old radio leads me to believe the V6 has an internal issue. I should hear back from MGL soon. In the meantime I will try to find a vswr meter.
 
guccidude1 said:
Other radios hear it as clicking. I originally had a factory RG-58 pigtail with a short length of RG-400 coupled in. I replaced the two pieces of cable with a single length of RG-400 from back of radio to antenna, a Commant CI-122. Now when the tx button is depressed, the TX symbol is steady but I get feed back in the head set and other radios report barely readable with noise in the background. I plan to have the avionics shop test the SWR tomorrow. Thanks for any others suggestions not already mentioned in advance, Dan
Click to expand...

Thats a typical symptom of a bad modulation FET. Hearing a click means the carrier is being output but mo modulation on top of it. This is usually caused by running the transmitter with a bad antenna or none at all. The RF power reflects back into the radio and the heat burns up the transistors.
 
A quick update for everyone. MGL sent me a replacement radio a few weeks ago. Before installing and retesting I removed the antenna back plate and polished the interior skin and antenna back plate to ensure it has a strong electrical bond. I also confirmed that my headset jacks are isolated from the airframe and that the radio has a solid ground. Retested the radio again and I'm unable to transmit clearly on 122.xx and 123.xx. The 121.xx frequencies that were garbled before are now OK. All other frequencies are OK. So now I am stumped. I'm tempted to pull and install the new Garmin experimental radio. I have a call into MGL, so hopefully they can figure something out.
 
What is your mike gain setting?

I was departing Santa Fe and center could not read my V6 on 132.8. I could hear broken/staticky transmission on my headset. Lower freq's were no problem. I had my mike gain at -12. After adjusting it to -9 transmission quality is much better. I've used the radio for 170 hrs and am happy with it, but it seems to take some time to get the settings right. I'd like to buy a good used one to take with me on long x-countries if anyone has one for sale.
 
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