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[AMPS] New Tube in SB-230

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Subject: [AMPS] New Tube in SB-230
From: (Joe Subich, K4IK)
Date: Fri, 28 Sep 2001 19:12:47 -0400


The SB-230 used a single 8873 (conduction cooled 3CX400A7/8874).  The 
power supply is quite low for the GI-7b (or 572B) providing about 2100 
volts vs. the 2800 volts or more required for the glass triodes. 

Given the low power supply voltage, I would look carefully at a single 
4CX400.  While the heaatsink would need to be ripped out and replaced 
with a blower/plenum, the power supply and output network (ca. 800 Watts 
output) are more appropriate for the 4CX400 or similar tube. 


   ... Joe, K4IK 

> -----Original Message-----
> From: []On
> Behalf Of Tom Hix W4TH
> Sent: Friday, September 28, 2001 5:56 PM
> To:
> Subject: [AMPS] New Tube in SB-230
> Tore;
> I vote for the pair of Svetlana GI-7b or GI7BT(same tube) triodes as
> replacement tubes for the SB-230.
> Tore if you will look at this page on my web site,
> You will see a conversion a customer of mine did on a Dentron amp that
> ran 4 572b tubes. He used a pair of the Svetlana GI7B triodes, and is
> getting about 1200 to 1300 watts out with about 50 to 70 watts of drive.
> I dont know the SB-230, so i dont know how much room you would have in
> the amp, but a pair of the gi7b tubes would be a little larger than a
> pair of the 3cx800a7 tubes. They would also be about $425.00 per tube
> cheaper than the 3cx800a7 tubes!
> I am not trying to sell you the tubes, my friend Anton at DXHAM.COM can
> put you in a pair of those very cheaply. I do have the sockets for those
> tubes however which are nearly impossible to find....Just telling you in
> case you need them.
> 73
> Tom.......W4TH.......Tom's Tubes
> xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Be sure to visit my web sites. 
> Tom's Tubes.  Russian Tubes our speciality..We now carry the Bliss Match
> Master line of antenna tuners and antenna switches.  Legal Limit PLUS.
> Ham Radio Homepage.
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