Mucho thanks to everyone who responded to my post, I will attempt to answer
everyone all at once here. Originally this was a Henry 3000D rf deck. It
had been rebuilt into a multi band HF amp by Jim Day in Bakersfield. I had
purchased the amp from a Amateur operator named David Shoen who lived up in
5000 foot elevation of Labec California. He was in the process of moving to
Europe at the time. When I went to look at the amp at his shack it was the
last piece of equipment in the shack so I was unable to test it. So not
being able to test it and seeming like a upstanding individual of the
Amateur society and not being able to test it, I bought the unit with a
decent discount
Once I delivered it home and fired her up low and behold nada output. So
after going through the components and testing them I found a bad tube, bad
vacuum tuner amongst a few other little things. So not feeling comfortable
working behind the person who built it I
gutted her out and rebuilt her from near scratch. Here is a excerpt of
specifications I was given on the amp prior to it going out of service,
SNIP............ "answers:it is an original design,not a henry remake.
The transformer is a Peter Dahl 4800v continuous at 2 amps.
full bridge power supply.rf section has no roller inductor,it is
band switched.yes to vacuum caps and vacuum relays.voltage sag
is 5% on ssb,and 7-8% on cw,excellent regulation.it puts out
7000 watts with 300w drive,and 8500w with 400w of drive on 160
thru 20 meters.idle current is 400 mils.When I drive it with my
ft-1000d,it runs abt.5kw.and with my old icom 730,abt.3kw.
I hope this answers your questions---oh,yes,it is shippable by
truck.
Thanks,
David" SNIP..........................
To answer some of the questions. Yes I am aware that the plate voltage is
higher then specifications, I know of many people using higher plate voltage
with out saveer detriment to the tube. Filament voltage is slightly above
spec, approximately 8.5 at idle and when in transmit drop a little under 8V.
After I get it functioning I had planned on using a variac on the primary of
the filiment xformer to dial it in. For testing purposes I wanted to use as
minimum circuits needed to see it run so that in the event there is a
problem I have less to go back and troubleshoot. I will add bells ad
whistles later.
How I did my tank circuit and achieved Q is with a MFJ Analyzer, I have
used the analyzer on tuning solid state amp combining networks and has
worked out great for that. A friend of mine has used it to tune the tank on
3cx3000a7, pair of 3cx3000a7, and 4x8877 and it worked out great. I am not
a mathematician nor do I understand scientific notations so I rely on simple
ways of achieving the same end result in the simplest way I can.
Now with that said let me explain what I did. I plugged in the MFJ to the
antenna connector and jumped out the antenna relay. I installed a
approximately 1425 ohm resistor from the plate to ground, I then played with
my band coil and vacuum variables until I was able to tune into a receiver
at the operating frequency on the MFJ. Then I read the MFJ readout to see
what the display gave me. I kept changing the coil until it canceled out
all the X (reactance) and was left with a purely resistive load of 50 ohms
at 1.1 SWR on the MFJ readout.
I did the same with the input Toll. The input consist of a air tuner going
through a approximately 1" dia. copper coil, and then through a 100pf door
knob to the filament connection on the bottom of the socket. When tuning
with the MFJ I had to tap the copper coil at the right spot on the wind to
get a good match.
So that's it in a nutshell, I hope I was able to clearly communicate myself.
If there is another way to cross reference my tank Q to see if its right
please share, I would like to try it.
thanks again for the help,
KRS
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