[Heath] SB-200 loading question.

[Kenneth G. Gordon]

I am somewhat confused here and I hope someone can help:

I am refurbishing an SB-200 for a friend. 

In this amp, C-27, the fixed 500 pfd 2 KV mica capacitor which is switched in parallel with 
the loading capacitor C-28A/B on 80 meters where additional loading capacitance is 
needed, especially on the low end of the band, had been replaced with a 525 pfd "door 
knob" capacitor capable of at least 5 KV. This "door knob" is a large one and I think it is 
actually either a 10KV or 25KV job.

It checks out with my cap meter perfectly.

While using this amp, with new finals, on the low end of 80 meters, I "run out" of loading 
capacitor before achieving full load. I.e., the loading capacitor is up against the full-
capacitance stop.

The antenna is being fed through a home-brew antenna coupler, and the SWR between the 
amplifier and the coupler is 1:1.

I then paralleled that "door-knob" capacitor with a 500 pfd 2KV mica, and STILL run out of 
loading capacitance on the low end of 80 meters.

The amp works perfectly and properly on all other bands and frequencies.

I then checked the bandswitch and every connection in the output tank and everything is 
working exactly correctly.

I then tried a different set of new finals, and got the same result.

Anyone here have a clue as to what is going on?

Even with the amp acting this way, I can easily achieve at least 600 watts output with 
around 50 watts of drive, and I am happy with that, but this still does not seem right to me.

Ken W7EKB
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