[Heath] Rebuilding another SB-200

[Dave Edwards]

I acquired a Heathkit audio amp a few years back....same situation. But, it 
worked...
Problem is that I don't think the builder knew he was allowed to cut leads 
to length!
It was horrible in there.
The fixes would have been a hugh task.
Instead, I took it all apart. Ordered new metal film resistors, and caps and 
terminal strips and rebuilt it.
It sounded so nice, I sold my fancy (expensive) Audio Research amp, and kept 
the Heath!!

Go for it Ken!!

.....Dave


----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
To: <Heath at puck.nether.net>
Sent: Sunday, September 25, 2011 5:43 PM
Subject: [Heath] Rebuilding another SB-200


> 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
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