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Amcomm HB 140 "Penetrator" amp info?

Discussion in 'Amplifiers' started by Robb, Mar 6, 2010.

  1. Robb

    Robb
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    Anyone one know much about these amps?
    A friend of mine was given one of these.
    10/15/20/40 meter switches on it.


     

  2. mrgumby

    mrgumby
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    W9WDX Amateur Radio Club Member

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    I had one for years tough little amp but dirty as hell...AND THE FINALS AREN'T CHEAP EITHER
     
  3. Robb

    Robb
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    Thanks for that tip - Mr. G.
     
  4. mrgumby

    mrgumby
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    W9WDX Amateur Radio Club Member

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    oh ya and not very good for ssb
     
  5. LeapFrog

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    Vocoder Frog

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    Hi Robb, did you ever get any more info on these?

    HB-140 bi linear, push pull with TRW PT9784 transistors.
    "Amcomm Penetrator", looks like a mid 70's CB amplifier.

    I was hoping somebody has seen a Palomar or Gray amplifier that used these odd transistors.

    I am considering swapping 2SC2879's or MRF454's into it and modifying/adjusting it for the input output impedance mismatch.

    Thanks for any hints!
     
    #5 LeapFrog, Dec 25, 2016
    Last edited: Dec 26, 2016
  6. Robb

    Robb
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    LeapFrog likes this.
  7. LeapFrog

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    Vocoder Frog

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    Thanks Robb, & Merry Christmas!
    I for sure want to make certain that the amplifier is biased above class C even @ the cost of power efficiency. This will likely require additional circuitry given the majority nature of amplifiers in the scene @ this era, but thermal tracking and controlled bias will be a focus for this project.
    [I may just leave it "old-school cool" & buy the factory N.O.S. transistors from that trusted place we all use, and then go from there to ensure the bias is not class C.] :D

    The blasted toy (HB-140) hasn't even been mailed out yet lol, I'm just digging for info that's all.
    The Texas Star Schematic will definitely help out for sure, If I decide to perform a conversion. (y)

    I spent a few hours looking in English web results for a schematic of this obscure amp, to no avail laugh out loud.
     
  8. Robb

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    The Texas Star schematic was just an example. You will notice that on it, it showed boxes for certain caps that change vales because they used different finals and therefore different capacitances - is all.

    Didn't mean to rebuild your amp to that schematic.
     
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  9. LeapFrog

    LeapFrog
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    Vocoder Frog

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    So to make the 2SC2879 transistors work, I shouldn't have to gut the box and copy the schematic I could just change the "matching network" (I don't know what this means) and some resistors/capacitors?
    Thanks
     
    #9 LeapFrog, Dec 26, 2016
    Last edited: Dec 26, 2016
  10. Robb

    Robb
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    That board may have different traces/schematic than the TS.
     
    #10 Robb, Dec 26, 2016
    Last edited: Dec 26, 2016
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  11. nomadradio

    nomadradio
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    Analog Retentive

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    Is this a mobile amplifier?

    I'm pretty sure you'll find that the transistors are the dreaded stud-mount type.

    Adapting it to accept flange-mount transistors will be a mechanical PITA.

    73
     
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  12. LeapFrog

    LeapFrog
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    Vocoder Frog

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    I am waiting this little mobile to show up in the mail, I will find out if they are stud mount. Thank You nomadradio. 73
     
  13. PA629

    PA629
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    If they are TRW PT9784's, they indeed are stud-mounted. I have an old amp from the 70's with a pair of them in it.
     
  14. LeapFrog

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    Vocoder Frog

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    The amplifier I have contains the "non A variant" of the PT9784, looks like a Toshiba 2SC2879 in the case style of "211-07", is this the same size as the Toshiba part? (I'm having a hard time determining if the mounting flange is identical from comparing the two datasheets)
    They look tiny in person, I was expecting these to look about the size of a quarter lol!

    Toshiba Datasheet
    TRW PT9784/A Datasheet
    Source: RFparts.com
     
    #14 LeapFrog, Dec 30, 2016
    Last edited: Dec 30, 2016
  15. LeapFrog

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    Vocoder Frog

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    And it's made in Florida, like me!
    .
    . Front ..
    Too bad they placed the band switch module directly underneath the transistors (sacrificing most of the heat-sink in the process).

    Back Filter/Band Switch PCB, PT9784 Band Select (Underside) ..
    Notice the statement mentioning: "Complies with FCC Regulations as of 4-15-77".
    I wonder if this unit was sold between April 15 1977 & Jan 1st 1978?
     
    #15 LeapFrog, Dec 30, 2016
    Last edited: Dec 30, 2016
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