KA9EAK QRO

I’ve always run a 100W or less station until now:

Heathkit SB-200

Heathkit SB-200

As my antenna situation is improving I can hear more and work more but I can’t consistently break a big pile-up with 100 watts so I started looking for a little help in the form of an amplifier. Obviously there are a lot of choices but I’ve always liked the SB-200. It’s reasonably well regarded and there is a small cottage industry for parts and upgrades. There were a fair number of them sold from 1964 to 1978 resulting in a pretty good flow on the used market at any given time and it gives me the amount of power I want for a reasonable amount of money.

After watching the various equipment posting sites for a wee bit I found a nice clean one that is all original. No hacks, no mods. It’s a little dusty from sitting for some amount of time but it’s all there including the original Cetron 572B finals.

Original tubes

Original tubes

Old power supply board

Old power supply board

While I fully intend to do the various Harbach mods. when it arrived I wanted to make certain that the power transformer was functioning so after a thorough visual check for potential problems I brought it up slowly on a variac and there was no excitement. It powers up fine, all the secondaries are functioning and the high voltage was 2100 V which is OK but a little low. No big deal as it will get a new power supply board which should largely solve that problem.

The next step was to place an order for the Harbach mods. I chose to do the power supply module, the soft start, the soft key, and the fan upgrades. Within a several days of my order the Harbach parts arrived in the mail.

Harbach mods

Harbach mods

The problem is that Fall is rapidly progressing and we are now three weeks out from Thanksgiving and it’s not uncommon to have some snow by then so outside work has taken precedence over the SB-200 project. I’ll have some time off work through the holidays to build the Harbach mods and get the SB-200 on the air. It will be nice to have around on occasion and I look forward to operating with it.

 

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