Many years ago when I had a 10A I used 4 6AG7s in G-G runing 1100 Volts on
the plate. Got about 300watts plate input power. I had them pressed into 1"
holes in an aluminum block fins cut in it using carbide tipped table saw
blade. And had a little fan blowing air on them. I used a TV power supply
transformer with a voltage doubler.
I could only get a couple of watts from my 10A because I replace the
pair of coils with bandswitched coils. Had two switches, one where the dial
lamp was and one where the 1/4 inch jack was located in the lower
corner. Most likely the low power was due to the fact that I had to
compromise on the link coupling coil one the plate for all the bands. Made
lots of contacts with that amplifier and later went to a pair of 4CX250Bs.
The last of the P&H 400 series the "C" version had a band switch
instead of the ARC5 antenna coil.
73
Bill wa4lav
At 02:45 PM 2/12/2009 -0500, Carl wrote:
>I believe that CQ carried the initial article and showed 6AG7's, 837's
>and modified 1625's. Id say late 50's or early 60's also.
>
>Looking thru some notes, I try to never throw things away, packed with
>those tubes is that I first used a 10B to drive a single 1625 which
>drove the 4, all in GG. Later on I used a 20A and just drove the 4. None
>of that lasted long as I soon had a HT-37 and followed by a 100V in 65.
>Apparently I never fried those tubes., never remember any tell tale
>glow. I still prefer the sound of a phasing rig.
>
>Carl
>KM1H
>
>
>
>
>----- Original Message -----
>From: "Glen Zook" <gzook@yahoo.com>
>To: "'Edwin Karl'" <edk0kl@centurytel.net>; <amps@contesting.com>;
>"'Carl'" <km1h@jeremy.mv.com>; <garyschafer@comcast.net>
>Sent: Thursday, February 12, 2009 12:30 PM
>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 <garyschafer@comcast.net> 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
>Amps@contesting.com
>http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|