I have always had a love affair with the Heathkit SB line of gear. It is what I drooled over as a kid in the1968 ARRL Handbook, on page 2 of the Advertisers Section. Years later when I worked in a variety of electronics repair shops (and eventually my own), Heathkit gear would cross the bench–along with the usual Collins, National, Hallicrafters, Hammarlund, Swan, and other suspects. Of all, I enjoyed working on Heath the best. Well engineered, simple circuitry, and solid performers for the price point.
There were design issues that still haunt us today. One of them concerns transformers–made for Heath by Chicago Standard Transformer, Stancor, or others. Depending on the contractor and time period, these could be a little ‘light’, meaning that if pushed to limits could fail. It was a cost saving design, and was solved later through Peter Dahl or Hammond replacements–and prevented through the addition of “soft start” add-ons.
The story of this particular amp began in 2008, when I rescued it from falling into Children’s Band usage. It received the full Harbach Electronics treatment–power supply board, soft start, soft key, suppressors, doorknob cap, and new relay. I was astounded to discover that these items in a bundle now cost $550!
I did not like the V-M phonograph motor for cooling at all–back in the 70s or now. The rig shown is the first one that I replaced it with a 220VAC muffin fan, which nearly tripled the airflow across the 572B’s and throughout the case. This amp still had original, very low hour Cetron tubes, and it was my goal to preserve them. Other additions were a back-to-back diode meter protection circuit, LED’s to replace the peanut lamp, an improved HV fuse link, bypass caps, and a front panel standby switch.
After this one, I did the exact work on six other SB-200’s–three for resale, and three for fellow hams. I like to believe that they are all still out there, complete with my call and signature inside of them. This one carries my old N4PRT call…
