Repurpose power amplifier out of trunk mount radio.

Discussion in 'Radio Circuits, Repair & Performance' started by KC9LGV, Jul 12, 2010.

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  1. KC9LGV

    KC9LGV Ham Member QRZ Page

    I have a couple of GE Delta 110w trunk mount radios that are in working condition. I was wondering how hard it would be to extract the PA board from the radio and use it as an FM amplifier. Although I am unable to find any hard information on the exciter drive current, I am guessing that it is somewhere between 25 and 350ma And there is a separate keying voltage that is applied to turn the transmitter. It is somewhere in the range of 8 or 10 volts but I don't remember which.

    I can get it wired up to try, but I don't have anything with a low enough output to drive it. Is there any way that I could attenuate the input drive enough to be able to drive this from an HT or a 10w mobile radio without an attenuator inline? Or a decent schematic for a fixed attenuator to tie onto the input would be good also.
  2. W0HC

    W0HC Ham Member QRZ Page

  3. KC9LGV

    KC9LGV Ham Member QRZ Page

    What all is involved on the Mastr2 amps? I am sure that the process is quite similiar.
  4. W0HC

    W0HC Ham Member QRZ Page

    Not a whole lot. the M2 series radios where fairly modular, so it was a matter of just chopping off the receiver, exciter, and control boards off of them. This left you with three boards, the driver, the PA, and the T/R switching board. In the case of a repeater setup you don't need to switch the relay, so there's no PTT signal even needed. You could just power the amplifier with continuous +13.8V and feed it RF drive as needed.

    I believe the drive was around 250mw, it's been years since I've worked on one of these. I believe the driver boosted it to around 25W, so you could bypass that and feed RF right into the final PA board if your drive was 10-20W.
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