[Amps] New linear Alpha 78

Jerry Kaidor jerry at tr2.com
Mon Jun 18 17:39:17 PDT 2012


Back from the Frigid North ( about 1 hour north of the QTH ),

   I have the Alpha 78 in hand.  Works fine.  We had a moment of panic
when the seller powered it up with the top cover off.  Flash went the
HV fuse!
First impressions:

   * This thing is a beast.  O my aching back.  It's also physically large,
     and visually overpowers the rest of the station.  But it "feels" like
     a piece of commercial equipment that won't need to be babied.

   * The blower is a little louder than I'd like.  I see RF Concepts has
     new blowers, not too expensive...

   * I'm not sure if I like the verniers on the plate and load caps.  I 
like to tune *fast*.  On the 30L1, I even turn off the transmitter
between trying load values.  Try a load setting, give it a toot of RF,
and dip.  Let it rest, try another value, another toot of RF & dip.

   * It's got a couple of big scratches on the top cover.  And several 
missing top cover screws.   That's OK, the top cover doesn't worry me
much.  Scratches on the front panel OTOH would be a big deal.  The top
cover can easily be repainted.  RF Concepts has a complete set of screws
for $5...

  * There's an elaborate QSK system that I don't understand yet, and might
not use.

  * It's going to be easy to switch the PTT.  The PTT voltage is positive
    21.5 volts, and when you ground it to transmit, you only need to sink
    2.5mA.  I'm thinking a 2N3904, a resistor, and a few bypasses.

                      - Jerry Kaidor ( jerry at tr2.com )
















> Hi Guys,
>
>    I have come to an agreement to buy an Alpha 78 from a local ( 1.25 hour
> drive ) guy.  Will probably drive out there to pick it up today.
>
>                         - Jerry Kaidor
>
>
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>




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