[AMPS] SB200 Filament Voltage

[dan hearn]

dan hearn wrote:
> 
> When I lived in Dallas, I purchased various sizes of low value power
> resistors from Tanner Electronics. These were for setting filament
> voltages to the correct value. They are a large surplus part outlet and
> prices are very good. They have a web page.
> 73, Dan, N5AR
> p.s. One of the resistors was a flat wirewound job with a center tap. I connected the two ends together as one terminal and the CT as the other. It was exactly the right value to set the fil V in a DTR2000A to the right value. I think these lo value resistors are used in switching PS. Tanner has mostly manufacturers surplus new parts.
> KG6DV@cs.com wrote:
> >
> > I found a very clean SB200 I couldnt resist.  While checking this amp
> > out I found an interesting situation, High filament voltage.  The
> > SB200 has no separate filament transformer. It uses one transformer
> > with three secondary windings. I have always put filament variacs in
> > all my homebrew amps but they all had separate filament transformers.
> >  The filament voltage on this amp measures 7.25 volts vs the 6.3 volts
> > required by the 572B'S.  Considering  the fact that this about 15%
> > higher than specs, Im not comfortable leaving it that way.  Is this a
> > common problem with the SB200'S ?
> > Any suggestions on how to correct the problem?
> >
> > Ron  KH6DV
> 
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