SB-200

[Mark Graalman WB8JKR]

 Also make sure the 33 ohm resistors are ok.
If need be pull on tube from the socket and run one at
a time at a max plate current of about 200 ma and see
if each tube acts the same.

Mark  WB8JKR


On Sat, 22 Feb 2003 12:14:09 -0600 Carlos Avellanet <avellanet at COX.NET>
writes:
> Hi gang,
>
> Here's an update on my SB-200 for all interested.  I replaced all 6
> power
> supply caps and bleeder resistors. The amp turned on fine and was
> providing
> about 600w output on CW and about 450w SSB.  Shortly after capacitor
> C-14 to
> pin 3 of V2 blew out with a fancy flash and a trailing plum of
> smoke.  The
> amp still works but power is down to about 300w CW and around 150w
> SSB.  It
> seems it is working on only one tube, though both tubes light up. I
> double
> and triple checked my newly installed parts and inspected the board
> for
> other damage--none found.  I replaced the cap and the power output
> is still
> down.  I wanted to check the tubes but discovered my B&K 707 tester
> does not
> support testing 572B's.  Troubleshooting is on hold until I can
> verify tubes
> condition.
>
> Question, some of this caps capacities are identified as uuF.  I may
> be
> showing my ignorance but I am familiar with uF and pF, what's uuF???
>  Nano??
>
> Carlos. KF4RRN
>
>
>
> > Hi gang, thanks for all the inputs on my SB-200 problem specially
> to Ray,
> > Mark, David, and Ed.   I was off work today and had time to play.
> Three
> of
> > the 6 power supply capacitors were dead shorts.  I checked all of
> the
> diodes
> > and they are all good.  The six bleeder resistors however, range
> from 17
> to
> > 23K.  No a single one close to the 30K rating.  I am going to do a
> search
> on
> > the net next to try to find some replacements.  The caps I already
> ordered
> > from Bill.
> >
> > I'll keep you all posted in hopes that my experience will benefit
> others
> in
> > the same boat.
> >
> > Thanks,
> > Carlos KF4RRN
> >
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