I remember an article for a grounded grid amp with four 1625s that used the
antenna roller coil from a command set as the tank coil. No cathode choke as
it was intended to be use with an exciter with a link output to provide the
cathode return. Very simple amp. I think that one version of the P&H used
the same rotary tank coil in their amp. You used the thumb wheel to change
the roller to change bands.
I modified lots of 1625s for grounded grid. The RCA and one other brand were
always connected internally and not usable. When ordering 1625s from fair
radio I would specify "non RCA brand tubes".
> -----Original Message-----
> From: Glen Zook [mailto:firstname.lastname@example.org]
> Sent: Thursday, February 12, 2009 12:31 PM
> To: 'Edwin Karl'; email@example.com; 'Carl'; firstname.lastname@example.org
> Subject: RE: [Amps] 1625
> I pulled my original SSB Manual and you are correct, the original "Four In
> Line" was grid driven. There was an article in QST in the late 1950s or
> early 1960s that told how to convert this linear (or build a new version)
> using grounded grid. The instructions for modifying the 1625 tubes was
> included. For some reason, I modified some 1625 tubes but never got
> around to building the linear! This was when I was in high school.
> I found a couple of those tubes when I was trying to clean up the shack a
> few months ago!
> Glen, K9STH
> Website: http://k9sth.com
> --- On Thu, 2/12/09, Gary Schafer <email@example.com> wrote:
> The "four in line" was four 1625s mounted in line that were grid driven in
> push pull parallel arrangement. Each side of the push pull circuit had two
> tubes in parallel.
> Getting old when you remember this stuff.
Amps mailing list