Many thanks to SWLing Post contributor, Dan Robinson, who discovered a very rareHammarlund SP-600 JX21A on eBay. Dan writes:

Collectors of classic boatanchor gear know what has been probably the rarest of tube sets year after year, decade after decade. That set is the Hammarlund SP-600 JX21A.

While there have been numerous JX21s on eBay, there has not been, to my memory, a single JX21A appearing. This particular model was a version of the SP-600 that was produced in small quantities in the 1960’s, and according to one writeup was the only one with a product detector and switchable sidebands. According to Radiomuseum it was the last model in the SP-600 series, and was recognizable for its knobs which were different because the silkscreen information was printed directly on the front panel rather than on the edge of the knob skirts.

According to Les Locklear’s excellent history of SP-600 models, the JX21A was produced between 1969 and 1972.

Now, an ultra-rare SP-600 JX21A has appeared on eBay. Like other models in the series, this would likely require replacement of numerous capacitors and a thorough refurbishment. The seller in this case has started bidding at a very low level, but if history is any guide, a rare model like this one may indeed go for thousands of dollars when all is said and done at the end of the auction.

Click here to view the Hammarlund SP-600 JX21A on eBay.

Amazing!  Thank you for sharing, Dan! What a gorgeous set. Though the seller states it’s in need of restoration, I’m pretty sure this one will get snagged up at end of auction. I’m very curious where the final price will land.

Are there any SWLing Post readers who own an SP-600 model–or the JX21A?  Please comment!