Quantar repeater showing "PA FAIL"

[Radioguy10]

Have a UHF Quantar repeater. PA Fail LED was lit. After reseating, reenergizing repeater, still shows PA Fail. I installed a "new" PA from MOTO and all was good, for a while. Now it again shows a bad pa. Attempted to align, with wattmeter and dummy load. It could not be accomplished and the RSS showed that I had a bad pa. The exciter shows all good. Any suggestions? Thanks.

[Bill_G]

Could be a bad repaired rfpa. Could be high vswr in your test cable, or the factory cable from the rfpa to the back panel connector.

[Radioguy10]

I thought about checking that. Only thing is, both PA's are (the original and replacement) are showing the same PA Fail fault. It doesn't seem likely that both RFPA cables would be bad. I am no scholar on quantars, what else in the repeater can give a bad pa fault? Thanks.

[khw]

If the repeater is accessible and you can connect a computer to it, go into the service menu and look at the error log. It will usually give more (a little) detail about why you're getting a fail light. For instance, if the problem is high SWR - the error message will say that. I once had a failing power supply that showed up as a PA Fail.

[Bill_G]

Both rfpa cables?

You must have something I've never seen because the rfpa cable I'm talking about is attached to the Quantar chassis. You slide the module in, and connect the cable to it. It's not attached to the module. It's a piece of 213 with a right angle NM at the module end, and a bulkhead NF on the back of the station to connect the xmitter antenna line.

The only thing that triggers PA FAIL is no or low power out. High vswr will trip the protection circuit forcing low power out, and thus the pa fail light. You can see high vswr in the diagnostics under metering.

Another thing that might be happening is the power level is set too high. The protection ckt is folding power back, again lighting the pa fail. Go into diagnostics, and recalibrate the power settings. Reinit the rfpa, and follow the procedure on the screen. There should have been a piece of paper from the repair facility explaining you needed to perform the power cal procedure before putting the station back into service.

If it isn't vswr or excessive power, then it's the pa itself returned from repair failed.

[Bill_G]

It just occurred to me you may be talking about both the input and output cables. I was only referring to the output cable. If the input cable is somehow broken, you could get an immediate failure from no drive. I have seen guys break the tips of the mini UHF connector off trying to get them disconnected. They didn't leave us a lot of room to work with.

The log file is a good suggestion. It would tell you if you have an exciter problem / no drive to the pa. You'll have to watch the metering screen carefully to see if it's a power supply problem.

[Radioguy10]

Thanks for all the advice and info. guys. Turns out it was a faulty UPS that the quantar was plugged in to. Ever hear of anything like that? I think because of the irregular AC being put out through the UPS during TX, it was causing the PA to fail. Anyway, system is up and running again. Thanks again for the advice.

[Bill_G]

It makes sense.