Qunatar Audio Issues

[fixanythingman72]

I have a UHF R2 qunatar in ham service. It has a controller connected to it but the station is configured as a repeater so that P25 is passed through it. The controller is connected to the aux tx and aux rx audio on the 25 pair punch down block. The wireline is then set as a higher ptt poriority so that the analog audio is handled by the controller. On Monday the repeated audio became extremely distorted, I assumed this to be a controller issue because the controler has had audio issues in the past. I was able to use dtmf commands to the controller to disable it. the repeater then ran fine using the internal controller.

yesterday I made it up to the site to replace the controller with a new Scom 7330. this is where the problems began. I could not get the wireline to take audio in. I was able to listen to the audio coming from the controller at the punch down block. but when I connected it to the repeater it seemed to pull it down and no audio was passed to the repeater. How ever I was able to jump the aux rx audio to aux tx audio and get audio to pass.

as the day progressed the repeater stopped putting out audio to the aux rx audio line and stopped passing audio on in cabinet repeat. The station keys but there is no pl or audio.

I would like to start by getting the in cabinet repeat working properely and then see what is going on with the wire line input. I am not sure what happened although we did also loose a NIC on a computer in the same rack during a storm on the same monday we had controller issues. Is it possible only these problems are related?

I am not sure where to start on the in cabinet issues. perhaps the wire line audio is an impedance mismatch issue? I have another quainter running with a 7330 just fine. then again maybe the wireline card is shot

anybody have a guess what might be going on?

Thanks!

[AEC]

You could have an impedance issue with the controlller and the wireline card.
Wireline usually run 600 ohms, I don't know what the S-com controller runs for audio impedance.
They also used to use, or need to use an audio delay module(ADM) for series such as the 7K line. Not so sure anymore though.
Check audio path for loop-backs, something is causing the TX audio in the Quantar to drop, otherwise you would hear a PL note.
Check the audio going into the controlle and coming out, noting levels, both in TX and RX, and the offset for both TX to RX.

[d119]

Hmm.. you've got more going on in there than wireline audio issues, I'm afraid. Do you have a spare SCM you can swap out and see if the problem continues? Have you tried reseating all the cards & modules?

[AEC]

Hmm.. you've got more going on in there than wireline audio issues, I'm afraid. Do you have a spare SCM you can swap out and see if the problem continues? Have you tried reseating all the cards & modules?

Most definately, there appears to be something 'sinking' the audio path, resulting is no TX audio/PL.
If not being transmitted, or at least, the loss of a transmitted AF/PL signal might be geting rerouted within the external controller.
But if any wireline is being used, it is always a good measure to repunch the wireline pair as it is very easy for the punchdown blocks to not have adequate pressure to cut through the insulation, making the connection make/break without being seen by the eye.

One added thing could be a severe impedance mismatch from the external audio path inputs to the wireline (if used).
Changing from speaker audio and usinng that over a mic impedance of 600 Ohms will cause problems with levels.

[fixanythingman72]

Thank you everyone for your input! I will reseat all the modules tomorrow. I definitely see where there could be issues interfacing with the external controller, however I am stumped why there is no audio when repeating internally. Is there something I can check with audio routing? how about alignment issues. Any advice as far as where to start with the loss of audio with the internal repeat would be greatly appreciated.

[d119]

Well based on the symptoms, something is either LOOSE or BAD.

Take a spare SCM up there with you, and, if after reseating everything, you still have the problem replace the SCM and reprogram and see what happens.

But as far as audio "dying off" like that, whooh... That's bad.

[fixanythingman72]

If I swap out the SCM do I need to realign the station? where is the alignment stored? Thanks!

[d119]

Alignment is stored in the SCM, so yes, you need to realign the station. If you have any form of service monitor, this is a pretty easy task if you haven't done it before. You need to know more about how to operate the service monitor than how to tune the actual station

[Will]

Can you copy the 'tuning' values and enter them in the alignment section of the new/rplmt SCM?

[Bill_G]

Can you copy the 'tuning' values and enter them in the alignment section of the new/rplmt SCM?

Not really. Some of the settings never display a value. For example the RFPA power adjustment keys the station and you tell it what power you're measuring. Hence the requirement to initialize the RFPA to scrub any stored values. But as a test, he can swap control cards between stations to see if it fixes his audio problem. He can do a full alignment afterwards.

Rereading the OP, I would pull the 25pr plug off the back, and reprogram the station as a repeater to see if it works. If it does, then I'd plug the 25pr back in to see if the replacement controller is loading things down, or possibly putting a DC bias on the lines.