[Heathkit] SB-200 issues.

[Kenneth G. Gordon]

I brought home an SB-200 amp that a blind friend of mine recently sold 
me. She had been using it for quite some time, but needed something 
that didn't require sight to tune.

I have discovered several issues with it:

1) One of the tubes was not lighting. This appeared to have been going 
on for quite some time. I replaced the tube socket and in the process 
discovered several no-solder joints in the filament circuitry. 

2) The grid-to-ground connection of that non-working tube was ALSO 
not connected.

3) After replacing the socket and redoing all the no-solder joints I could 
find, it appears that the amp is working. Power output on 80 meters is 
around 750 watts. HOWEVER, one tube, apparently the tube that had 
been doing all the work, gets a very red plate even if the tuning time is 
kept to a minimum. Furthermore, there is the number "40" written on 
that tube in black ink. Sounds to me as though that particular tube is 
pretty flat.

4) The final "loading" knob is over against the fully-closed stop, even 
with an SWR of 1:1. Sounds to me as though the 500 pfd cap that is 
supposed to be paralleled with the loading cap on 80 meters isn't being 
connected.

5) There is no grid current showing on the meter with the meter switch 
in the grid position.

6) It appears that the SWR input is quite high, as the loading control on 
the driver, an SB-102, has to be set fully to the right-hand stop.

I would be pleased to hear comments from you all about these issues, 
to confirm my own ideas.

Thanks,

Ken W7EKB