circulator?

[Dan K]

I Have a Micor Compa Station. I am only useing the power supply rack and PA. What I'm trying to do is to cut down the PA power from 100watts to 50watts I removed the Micor circulator and I installed it in line but where do I supply the power to it and how much??? :roll:

[Microwave Mike]

The circulator is a passive devise. RF goes in then out to the antenna. When RF from the antenna goes back the other way to make nasty intermod products from the Final, it is instead routed to the load resistor, a 50 ohm load.
To lower power form a final amp, just lower the drive RF to the input. Most exciters will have this option. If it does not you may employ a devise called an antenuator. They are made in 1-30 DB steps. Remember that every 3 db will half your power. If you drive is 10 watts to get 100 watts out, then a 3 db attenuator will lower the drive to 5 watts. This should get the output down lower, but the ratio is not always linear. Some testing should be done.

Good luck

MM

[Dan K]

Well I think I screwed up my PA Real "GOOD" :( I tryed to lower the out put by decresing the voltage to the control pin on the PA I got a steady 40 watts out. Well I thught I concured it. But when I was adjusting the reject side of the RX duplexer to remove some desence I noticed ther was no power comming out of the PA I adjusted the power to the control pin and only when I cranked it up to 13 volts I got a little power out and after a while then nothing:( Also befor all this I did turn down the exciter but could not ge a steady power level out. I guse I could give a stab at fixing it but I can't find a schamatic any where on the net it's a Micor UHF PA 1979

Thanks
Dan

[Dan K]

Well I think I screwed up my PA Real "GOOD" :( I tryed to lower the out put by decresing the voltage to the control pin on the PA I got a steady 40 watts out. Well I thught I concured it. But when I was adjusting the reject side of the RX duplexer to remove some desence I noticed ther was no power comming out of the PA I adjusted the power to the control pin and only when I cranked it up to 13 volts I got a little power out and after a while then nothing:( Also befor all this I did turn down the exciter but could not ge a steady power level out. I guse I could give a stab at fixing it but I can't find a schamatic any where on the net it's a Micor UHF PA 1979

Thanks
Dan