[Amps] Question #2: 4-125A linear amplifier

[Carl]

----- Original Message ----- 
From: "Roger (sub1)" <sub1 at rogerhalstead.com>
To: <amps at contesting.com>
Sent: Wednesday, May 11, 2011 11:26 PM
Subject: Re: [Amps] Question #2: 4-125A linear amplifier


> On 5/11/2011 10:44 PM, Robert Groh wrote:
>> OK here I am really going to tempt the gods with a strange idea of a 
>> 'classic'
>> medium power amplifier using one or two of my 4-125A tubes - HF, window 
>> in the
>> front so I can watch the tube plate(s) glow, driven by a CE 20A exciter. 
>> Maybe
>> just a couple of bands, maybe one band. Couple of ideas already in hand 
>> from
>> past issues of QST (I haven't had a chance to prowl through the old 
>> Handbooks).
>>
>>
>
> Too bad you aren't closer.  I have the remnants of the RF deck for a
> 2-meter amp (GE I think) that uses a pair of 4-125s you could have, but
> I don't want to ship it.  Sockets and tuned lines.
>
> 73
>
> Roger (K8RI)


That sounds like the one I have here, suspect its an old FAA amp used as an 
AM linear prior to the AM-6154/6155. With very little work it puts out 400W 
on 2M FM where Ive used it for contest points for the past 25 years. A close 
copy was also in the ARRL HB for many years.

A pair of parallel 4-125A's will run 600W out of fairly clean SSB in AB1 
grid driven; a 20A is perfect for a driver.

Carl
KM1H