rebelflier

rebelflier

Member
I have had an intermittent problem with my radio that has gotten worse. I also have a Sigtronics SPA-400 intercom. At first I was getting complaints that my transmission was garbled and lots of static. This weekend it's gotten to where it has no side tone in the headsets when transmitting, and all people hear is the click when keyed. What is strange is that it works fine on the ground with the engine off or at idle, but as soon as you bring up the power it messes up. I have checked all connections, grounds, cleaned the radio inside and out, replaced the BNC connector at the antenna. I did discover that the builder neglected to isolate the Mike and Headphone Jacks from the panel, so I made some plastic washers and reinstalled. I even tried switching mags in flight because someone said it may be a mag problem. I have taken the intercom out and checked the connections, and even tried to adjust the level (mod adj). With it turned all the way up it improved a little. If I turn the intercom off it still doesn't work, so I don't think it is the intercom anymore. I have nearly 200 hrs. on it and have only had problems the last 10 hrs. I have tried multiple headsets and the co-pilot PTT, it makes no difference. If the local radio shop works on Val, I will probably take it in next week, but they are at a towered field (KCXO). I am not sure how well a hand held will work, it's noisy. I put a want ad on classifieds looking for one to swap out, that would be easiest. At this point I have run out of ideas. ..ANY OTHER IDEAS?
 
Last edited:
Somebody has to have something else I can try today...I don't mind double checking something if someone else has had a similar problem.
 
Sounds to me like the output is fried, however you might try ringing out the wires from the mic audio/ground to the radio (pin 18 & 9). No sidetone means no modulation so either the audio is not getting there or the radio is kuput.

If it works with the lower voltage 12v (eng not running) and then fails with 14v with the engin running that would bring me back to a failed radio.
 
I have determined voltage is not the problem, I turned the alternator off and no change. I did adjust the side tone adjustment and it seamed to help a little. I got a "loud and clear" when asking for radio check, but it is still intermittent. It maybe heat or vibration related. I can change RPMs and get it to work. I wonder if not having the jacks insulated from the panel for so long could have damaged it or if that is just to reduce noise. Thanks for the help.
 
It Works

Thanks to a fellow VAF'er I got a good working radio. Now I'm going to send the bad one to VAL to get it fixed so I will have a backup.
 
You must log in or register to reply here.