The Hammarlund SP-600 JX-17 is an example of a laboratory-grade HF receiver dating from the early 1950s. Indeed a “boat anchor”, the SP-600 line was built to the R274 military specification, which also included the receiver that became the Hallicrafters SX-73.
I had one about 15 years ago, I do not recall it being very sensitive, but it was different in its mechanical tuning mechanism and availabile crystal control; a glorious receiver!
These are amazing receivers. I have two JX-14’s (the best of the SP-600s IMHO…) that took me 2 years to restore, working in my spare time instead of steadily. I will not part with them for any amount or offer or consider any trade for modern equipment. They have no equal, except maybe for the Collins R390-A, which is another amazing receiver in its own right.
I have a Super Pro SP-400-X that has been in dry storage for about 30 years. Any advise on how to best re-awaken it gently. I was a very active SWL in the 60s and 70s and would like to operate this set again.
Briefly, don’t just plug it in and turn it on. Bring it up slowly to full 115 VAC using a variac over about an hour’s period. This will help reform the electrolytics. It would be preferable, of course to first replace the power supply’s electrolytics, as they are likely leaky and can cause all sorts of problems. If they short out they can destroy tubes and even power supply transformers.
Thanks for a quick response. The ac power supply for this radio is a separate unit, so maybe easy to re-cap and then test out independently.
Excellent article!! I recently acquired three SP-600’s. One is a JX-17: I replaced the main electrolytics and the cracked black beauties and brought it up on a variac. It works! Cleaning the switches and turret contacts smoothed it out considerably. The plan is to replace all of the capacitors in the 600 shortly.