[Heath] Rebuilding another SB-200

[Kenneth G. Gordon]

Some time ago, I bought a second SB-200 off eBay because it was unusually inexpensive, 
and I figured I could use it for parts.

It became quickly apparent that some CBer had "modified" it for use on 11 meters. At one 
point, he had gotten the final amp tubes so hot they scorched the plate coil form.

Furthermore, the 10 meter grid coil had had a turn added to it, and the tap on the final amp 
coil for ten meters had been moved.

Other than those, the amp was actually in surprisingly good condition.

I checked out the power transformer, expecting it to be gone, but it is still apparently perfect.

At this point, I decided to use this, instead of for parts, to experiment with.

So, I started by replacing all the power supply filter caps, the equalizing resistors, and all the 
diodes, and upgraded the HV metering resistors. Upon firing it up, the meter read +2410 
VDC in the HV position of the meter switch, and the tubes I had installed lit up just fine.

The wiring job under the chassis looked reasonably well done.

So far, so good.

I wanted to modify this SB-200 to enable coverage for 160 meters and the WARC bands, and 
to convert it for full QSK keying using that high-speed switching mod designed by Rich 
Measures.

To begin the process, over yesterday and today, I examined the wiring at the rear of the two 
tube sockets, discovering big blobs of solder, components held in place by solder only, cold 
solder joints, leads not properly dressed, leads too long, etc. I was appalled. The wiring, at 
least that in back of the tube sockets, was really bad.

It appears that two different people built this amp. Perhaps one started the process, and then 
sold it to another who "finished" it.

There was also a "smoke mark" on the chassis from what I can only assume was one of the 
33 ohm grid resistors letting out its magic smoke, and one of the 200 pfd grid capacitors was 
missing.

So, I am going to proceed in an orderly manner to rebuild this amp the best I can, and will 
keep the list informed. Some may be interested. Others can delete what I write.

vy 73,

Ken W7EKB