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RF Plasma Products Inc. Model RF-10 Solid State 1kW Amp

Discussion in 'Amateur Radio Amplifiers' started by KI6R, Jan 18, 2019.

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  1. KI6R

    KI6R Ham Member QRZ Page

    I just picked up an old model RF-10 solid state amp made by RF Plasma Products Inc. It is wired for 220VAC input and is supposed to be good for 1kW on the HF bands. The finals are MRF-150 Mosfet push-pull amps which are combined. It will require lowpass filters to meet emissions specs. Does anyone have any information, schematics, manuals or know anything about using this amp as an HF linear? Any help will be appreciated. 73, Ed, KI6R (ki6rcm98@gmail.com)
     
  2. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I don't, but used to work with this company quite a bit back in the 1980s (it was "PlasmaTherm" then, and Len West was chief engineer).

    AFAIK all these plasma generators/amplifiers are fixed-frequency operating on 13.56 MHz I'd think the only HF band where they'd work properly would be 20 meters.
     
  3. AA7QQ

    AA7QQ Ham Member QRZ Page

    Weren't some on the 27 Mhz band? Seriously.
    I will guess that the best place to find the schematic will be the Motorola data sheets or application notes. It might even be the exact same board.
    Be sure that it has the proper bias.

    Ed
     
  4. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    That particular amplifier is part of a plasma generating set, and it's tuned to 13.56 MHz, period. I know it pretty well.

    The RF circuits are not terribly broadbanded -- although serious modifications might allow that, but it would require those modifications, and bandswitched low-pass filters to follow the PA.

    The 8877 tube in my 6m amplifier came from the same source (PlasmaTherm), it was a "pull" from service and still runs 1500W output on 50 MHz. I bought it in 1984 for $100 and that worked out well. They made plasma generators up to several kW.
     
    AA7QQ likes this.
  5. AF7XT

    AF7XT Ham Member QRZ Page

    27.120MHz but not this one. The tank is semi fixed having a single inductor but limited resistive and reactive capacitance . I suppose a bandswith/multiband tank circuit could be constructed. It would be either hit and mis or find an amp using the same tube and copy the tank. Then there is input tuning and ...
     
  6. AA7QQ

    AA7QQ Ham Member QRZ Page

    I do not understand why there would be a tank circuit in a solid state amp.

    Ed
     
    N8CMQ likes this.
  7. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    It has fixed-tuned input and output circuits, not the very broadband ones used in amateur radio SS HF amps.

    I also don't know (could probably find out) how "clean" these SS amps are: For their intended application, they don't need to be very linear and "might" create significant distortion to a signal -- which again, for their intended application, wouldn't really matter.
     
  8. WB5WPA

    WB5WPA Ham Member QRZ Page

    Can we see a picture or three? Who knows - the 'board' design might be straight out of the Motorola applications note for the MRF-150 device.
     
  9. AA7QQ

    AA7QQ Ham Member QRZ Page

    Quite possible, Steve. But, back a few decades ago, I scored several MRF150 amps from solder reflow units. They had boards that were exactly like the Motorola notes , except for Class C & fed into a box with a huge coil & carriable cap to match it to the reflow machine. We tested the amps & they worked as advertised, per the Motorola notes, except for being Class C. THe traces & lands were there for proper bias, but they just had a wire to ground & ferrite bead on the center of the secondary of the input transformer.

    Ed
     
  10. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    With this specific amp, although that may be the case, I don't think it is.

    I knew the chief engineer there for years and he designed his own stuff, usually specifically to optimize efficiency at 13.56 MHz using tuned circuits that can handle serious power with less loss than broadband circuits. However, I don't recall this specific design -- they made a lot of plasma generator products over a long period of time.
     
    AA7QQ likes this.

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