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Anybody Still Running QEI Transmitter?

R

RF Man

I recently inherited an QEI transmitter at one of my stations. When I first saw it I could not believe my eyes as I had not had seen or heard of that brand in over 20 years. This one happens to have 4 IPA's and one final tube. Anyone have any experience or advice on these rigs? Thank you in advance.
 
Got a 30kw FM unit as a backup at one of my sites. I've had a few minor issues, but it works well for the most part.

RFB
 
It is an FM. Model FMQ-30000B. Trying to tune it recently other engineers blew 3 IPA modules in the process. Having 4 IPAs does not give one a warm fuzzy feeling as all my other rigs use only one.

Any advice would be appreciated.

frankberry said:
Is the transmitter AM or FM?
Model and power output?
Click to expand...
 
Call iBiquity, ask for Bob Detweiler. If he's not there, get a number. Call him. Say "Bob, I got a 30KW QEI radio. Who was the guru on this one, and do you have any idea how I might get hold of him?"
 
RF Man said:
I recently inherited an QEI transmitter at one of my stations. When I first saw it I could not believe my eyes as I had not had seen or heard of that brand in over 20 years. This one happens to have 4 IPA's and one final tube. Anyone have any experience or advice on these rigs? Thank you in advance.
Click to expand...

I'd begin by running the exciter into a dummy load to check it with a spectrum analyzer to insure that it is not putting out some crazy out of band spurious signal which might be sending the IPA modules into destruction. If the exciter checks out to be good then check the power supply to the IPA modules. Repair the IPA modules and run the IPAs into a dummy load. Do this one module at a time if possible. You didn't explain how the IPA modules are arranged. Likely in parallel or series parallel. Knowing the order of the modules and which ones went bad could give you a clue. If you can get all of the IPA modules up and running into a dummy load with out a problem the next step would be to bypass the IPA completely by running the exciter to the PA. Then you could start out with only a few watts and go about your tuning. Get the tuning good and then you can put the IPA back in line. Start out with very low drive from the exciter and slowly increase it and watch the meters for any sign of trouble as you go.
 
That's a different model than my auxiliary unit. I have the earlier version that has one solid state IPA module feeding a 3kw tube driver section that feeds the PA. The solid state IPA modules are a real pain to work on and the RF transistors they use aren't cheap. The only issues I've had with the IPA were dried electrolytics and a piece of RG-174 cable falling apart due to heat / age.

RFB
 
I ran that model for many years down in Corbin City, NJ. When I first took over the site the air conditioning in the shack was inoperative, I got that squared away and on my first attempt to bring it up to pull power blew three of the IPA modules (the over heating situation in the shack), literally when i took the IPA's out there were pieces rattling around (KABOOM! :eek: . Anyway squared that away and was able to tune up the xmtr kind of ok. Tom McNally (WFPG Atlantic City, NJ nows has that xmtr and from what i hear it is doing ok as a backup). Some of the things i saw on that xmtr were shorted HV diode stacks, dirty drive pot on the old QEI exciter, burnt PA Tube socket etc etc. Pay attention to the IPA metering (the buttons arent the best but they will give you an indication of your IPA's). And when you get frustrated :-\ call Bob Detweiler.

Ray
 
I'm taking one off-line tomorrow ;D. I can't remember the model #, though (its a ss FM circa-1986). I had to replace all the fans on it last year. Contrary to my preferences (Nautel, BE, Continental), the station bought a new Harass ZX1000 to replace it. I do not have direct experience with the ZX-series - just hoping it doesn't require a call to tech support.
-D
 
The guys who really know these rigs are Ed Etchman and Bob Brown at QEI. 1-856-728-2020.
 
I thought Bob left QEI ... Not sure though. Nice folks ..... My Corbin City xmtr site was not far from the QEI shop at the end of the airport. It made it easy to pick up parts etc.

Ray F
 
It's Jeff Detweiler, not Bob. But I'd be talking to ED or BOB at QEI.

RE: earlier comment about being apprehensive about multiple IPAs. Having multiple IPAs means of ONE fails, you can still operate, likely at reduced power.

The IPAs are connected by a splitter on the input and a combiner on the output.

The FMQ-10,000B, which I am familiar with (we have two of 'em), uses 3 IPAs.
 
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