I don't really have enough plate voltage on them right now. Under load ended
up with around 1700 volts. But, that is what I get out of the transformer that
I had in the junque box! The plate current is right at 600 mA which gives an
input of about a kW. The 700 watts output is what I am showing on both my
Collins 312B-4 and on my old Swan 1500 watt meters. Now I realize that the
absolute readings do have a tolerance!
When I locate a transformer that can put out a higher voltage under load I need
to change it out. Also, the junque box transformer only has a 120 VAC primary
and I definitely like to run my linears from 240 VAC.
I ended up using a W4ZT bias board and adjusted it for an idle of about 100 mA.
I don't have a grid current meter installed so I don't know exactly how much
grid current the tubes are pulling. The input is not tuned and is loaded with
a 50 watt 100 ohm thick-film resistor. I am using an old Hammarlund HX-50A for
the exciter and it is rated at 60 watts output. But, I usually get around 70
to 75 watts out on 160-meters.
I homebrewed the socket and there are a couple of photos at
http://forums.qrz.com/showthread.php?282380-Socket-for-Russian-tubes
Photos of the basic amplifier are at
http://forums.qrz.com/showthread.php?284611-Almost-ready-for-smoke-test
Since I am the Head Moderator on QRZ.com I put the information in the
"homebrew" forum on the site.
The idea was to build the amplifier for the lowest cost possible using junque
box parts whenever possible. Fortunately, I do have a pretty well stocked
junque box!
Glen, K9STH
Website: http://k9sth.com
--- On Mon, 2/28/11, Gary Schafer <garyschafer@comcast.net> wrote:
Interested in the parameters on the GI-7B tubes. I have a pair here to put
together.
What plate voltage do you have on them?
How much plate current?
How much bias?
Plate idle current?
Grid current?
Drive power?
Output you said was 700 watts.
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