| Heathkit SB200 Amplifier |
| This amplifier appeared at the 2002 Shelby, NC, hamfest. The story was that it had been shipped back to the states from overseas and arrived with the tubes missing. |
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| When I got the amp home, I found that only one tube was missing. The one remaining did not have a plate cap. The amp was very dirty, it had been dropped, and cabinet screws were missing. The filter capacitor PC board was cracked, the case was warped, the panel meter was dead, and the cooling fan would not move. |
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| With a trip to Ace hardware, I found some screws to firm up the cabinet. I replaced the filter caps with 470mf/450 volt capacitors. I re-soldered broken traces on the printed circuit board. I found a Simpson meter which had the identical appearance to the original Heathkit meter. I moved the scale over to the new meter and added a shunting resistor across the meter so that it would cover the same
range as the original meter. A few squirts of WD40 loosened up the cooling fan. I plugged in a pair of 572Bs from the junk box. I then plugged in the amp with my long extension cord! (Really, I brought it up with a Variac.) Amazingly, the amp worked! I upgraded some of the circuitry with modifications from the Mule website: http://www.palacenet.net/home/mules/sb200.html The front panel had tape and dirt on it; I scrubbed it with soap and water. The outer cabinet was in rough shape; I cleaned it and used a spray can of Valspar Willow Satin # 165919. This is a fairly close match to the green of the original Heath SB line. I found this paint at the local Lowe's store.
Here's how the SB200 came out. |
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| With 50 watts of drive, this SB200 puts out between 500 and 700 watts on 80 - 10 meters. |