PAR 100EX install problem

Just talked with Don at DeltaPop while troubleshooting my installation of a PAR 100EX Radio/Audio panel (what a great guy!). He suggested I consult the wisdom of the Van's Forum.

Here is the issue- Install of the audio panel and remote radio is complete. Radio receives fine but when attempting to transmit with PTT switch it just gives a series of rapid clicking noises in the headset and is not received. This is with the engine off. The transmit indicator on the audio panel blinks as it is supposed to, but no transmission. I have checked all of the wiring and confirm there are no extraneous grounds and everything is in order, i.e. each pin throughout goes only to the appropriate location and there are no shorts, pin-to-pin. Everything is shield and shields grounded as per plan. The phone and mic jacks are not grounded and each termination has been checked for grounds or shorts and none are present. I've been troubleshooting this for 3 days after completing install and cannot find any issues and am confident with the wiring, at least its path and no grounds. Everything is mil spec wire and connectors. I even disconnected the PTT switches at their connectors and just inserted a wire to bypass the switch to check out the switches.

I'll gladly contribute a beverage of choice (6-pack or bottle) to anyone who can solve the issue- assuming it's an install problem. The radio was purchased from a panel upgrade from an avionics shop that stated the system was checked out and functions fine, but the only option I have left (following any advice) is to return the unit to the shop, which charges $200 to inspect in addition to any repairs and parts, and lose another couple weeks of flying time.

I'm anxiously awaiting any suggestions!!

regards,
TR

trib said:

Here is the issue- Install of the audio panel and remote radio is complete. Radio receives fine but when attempting to transmit with PTT switch it just gives a series of rapid clicking noises in the headset and is not received.

Click to expand...

A little clarification of this statement might help......

You said radio receives fine, but it is not received?

You mean nothing received as far as a transmission when listening with another radio?
Can you tell that a carrier is being transmitted (squelch on listening radio gets broken).
What radio is connected to the audio panel.
Is it one that has its own transmit indicator light? If so, if that doesn't light when the one on the audio panel does, then you have a wiring problem between the radio and the audio panel.

Disregard... I didn't realize they ever sold an audio panel with a built in com radio

Since it is with the engine off, what is your battery voltage reading? If it's low, I could fathom a situation where a radio could receive (low power requirement), but when transmitting, the voltage drops a little too low to operate. Perhaps charge battery and try again?

Also, have you ever activated the push to talk button without an antenna connected? If you haven't, don't - it's no good for the radio. Point is, if you have, that could have caused some internal damage to the amplifier.

There are a few other things to try, like adjusting side tone, but as Scott mentioned you'll first want to see if carrier signal is being transmitted. You can test this with a handheld radio or a nearby aircraft. If the squelch breaks and you can at least hear static, that's a good sign.

We did this installation a few months ago. Same thing happened to us. We could receive, but not transmit. When we tried to transmit, the light would go on, but nothing. (We didn't get the clicks like you do) We called PS Engineering who said it sounded like the transmitter was bad. We sent it in, they sent a new one, problem fixed, and it works great.

I don't know your warranty status, but It's worth a call to PS Engineering if you haven't already.

Good Luck.

Voltage

I'm betting the voltage was too low. I got that clicking noise once in the hangar too on just battery power. Charged it up and no issues and never any issues under alternator power with engine running. Otherwise, no issues with my par100ex / deltapop configuration.

I am with Derek on this. Especially if when you try the passenger side, you get the same results.

**AND** what is the voltage on the battery? If it is too low to turn on an EFIS (<10 volts) then the drain of a "transmit" may be just too much for the output stage of the radio. There is little current required to receive.

If charging the battery does not fix it and you get the same on the passenger side, give Matt a call at PS Engineering. He will take good care of you.

Check voltage levels at radio

I too, am thinking that the radio is not getting proper power. I would put my bet on a loose connection somewhere, maybe even a ground. You need a solid path from + battery through the battery master fuse, etc to the radio, and then ground return all the way back to the battery. You no doubt have power there, may have a high resistance connection somewhere. This is not an issue when not transmitting, as the radio is only drawing mA then. Once you press transmit, you're trying to pull Amps of current. At that instant, a high resistance connection could drop several volts.

To test this, you'd have to connect a voltage meter to the radio's power pins Nd watch for a voltage drop while transmitting. I don't know an exact value, but I'm guessing you shouldn't see more than a 1 volt drop. Again, my guess is your ground return. How is the radio grounded (what is the path for current to return to the battery. Tug on all the faston connectors and ensure a snug fit.

Good luck,

David