On Mon, 2009-08-31 at 19:39 -1000, Ken Brown wrote:
> > superseded after the Korean War by the similarly-powered Barker &
> > Williamson T368 (Eimac 4-250 tetrode in final amp).
> And a pair of 4-125 in push pull to modulate the 4-250.
> > It was fully band-switched 80 thru 10 meters.
> Probably 2-30 MHz.
> It also had a built-in VFO (I think they called it a "MO" master
> oscillator), which was a Collins type (perhaps Collins manufactured) PTO.
I picked up an unknown to me Collins PTO last year at CSVHF. Turns out
to be the PTO from a T368. A 70H9 made by Collins but with the model
number written on the label by hand.
> There was also an amplifier often paired with the T-368 (and perhaps
> earlier with the BC-610) which used a pair of 833s in push pull, with
> plug-in tank coils, not band switched. (maybe it had a band switched
> input circuit, but not the output) The MARS station I hung around had
> these. I wonder if anyone following this thread happens to know what
> that piece of equipment was called?
> At the MARS station they used R-390s and T-368 for RTTY service. I don't
> know if the pair of 833 could be operated as a linear amp, with the
> T-368 in AM, or if it could only be used for CW and FSK.
Depends on bias and drive levels. In broadcast transmitters many a pair
of 833s were modulated by a pair of 833s to give a KW AM output.
> As far as I know at that MARS station the only fone ops were done with a
> KWM2A and 30S1. The T-368 were used exclusively for RTTY.
Once MARS went to SSB, it tended to ignore AM simply because SSB worked
so much better and used less spectrum.
AA4WCC at Ft. Belvoir (VA) had a collection of equipment. The newest
when I was there was a KWM-2A and a Henry 2K-3 amplifier. They also had
a Viking -500 with NC-303 and a 75S-1 (or 2) and 32S-1 (or 2) and a
30S-1. I used the viking or S-line on 80 CW on a weekly sked with my dad
(K0CPN, now SK). One night the bands to Nam were dead and the S-line was
ill so I got to use the new KWM-2A and Henry for my sked (didn't really
need the power but it made for good copy at the other end and my dad was
practicing to get his code speed for for an extra) and had to back of
the drive to get the output down to 1.5 KW. The MARS ops wouldn't let me
go back to my barracks until I made them a new tuning chart for the
Henry based on maximum output rather than plate and grid current
readings alone. I got 2 KW, their tuning got 200 watts. Enough change it
was noticed in Nam the next where the ops told me the Nam station said,
"I see you finally got the final turned on." I don't remember a T-368 or
much RTTY gear there, but I didn't get to wander through the catacombs
(old wooden army hospital complex). I did repair the gear on occasion
including the Henry 2K-3. Two shifts of two Army radio ops (not hams)
ran phone patches every day. They had at least a couple phone lines so
the domestic side of the next phone patch could be set up while the
previous patch was going on for keeping the RF circuit busy.
> DE N6KB
73, Jerry, K0CQ
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