[Boatanchors] Progress on 1-KW W6MSC transmitter revival

[Chris Howard]

I've made some good progress recently on my 1-KW
transmitter which recently came my way from the builder,
former W6MSC.

I removed the rectifier deck from the rack and produced
a schematic.  That has helped a lot in figuring out
some of the interconnections that were unmarked.

There really aren't a lot of parts, but most of
them are big!  and heavy!  

After that, I re-racked the rectifier deck and did some
experimenting with the 6.2KV plate transformer, solidifying
my understanding of where to hook up to the primary.

Then I got the modulator deck out and I've looked that
over.  There is some audio signal shuffling that I don't
completely understand, but generally it looks like the
picture in the ARRL Handbook (1960) that I've got here.
Although I don't have the tubes, I believe it's using
4 813 tubes, two on each side of the push-pull.
>From some incidental markings, the plate voltage appears
to be 1500 volts, which the 813 datasheet says is one of
the lower-powered configurations, producing 260 watts with
two tubes.  I've got what says is 750 volts going
to the screen, and a separate grid bias supply... just 
like that datasheet says.  When Bill built it he
put in separate grid drive controls for each tube, and a
plate current meter for each one.  One thing not
obvious is what audio level input is necessary, mic level
or line level?  It looks like a balanced input straight
into an audio transformer.  But I can figure that out
with the o-scope when I get it fired up.

I need to tackle the deck which contains the modulation
transformer and some other modulation iron.  I think he
may be using a Heising type of modulation, although there
appear to be some notes indicating something called Doherty?
I've got a couple of large chokes in addition to the
mod transformer, but I don't know yet how it all connects
together.

I think I'm actually starting to understand this thing
a little bit.  It appears to me that most of it
is one really big power supply.

Chris -- kc0atc

(some pictures of the various parts and pieces are
accessible from www.yipyap.com)

-- 
Chris Howard                                     YipYap.Com
chris at yipyap.com                                 Estes Park, Colorado  USA
current Estes Park weather --  http://www.yipyap.com/wscurrent.html