THE HALLICRAFTERS S-38
If you were a kid in the 50's and crazy about shortwave radio then you will know what looking at a Hallicrafter's ad could do to a person. I spent far too much time looking at ads like the one above, dreaming someday of actually owning a HALLICRAFTERS! It seemed that one of the requirements for owning a Hallicrafters was to always listen to it while wearing your best suit and tie, or so the crafty ads would have you believe. This was very powerful stuff for a ten year old kid. I have, over the past few years, been able to build a collection of a number of old Hallicrafters radios, probably due to some form of post-hypnotic suggestion deeply imprinted within the brain of that ten-year old radio-boy by those devious and long-gone Hallicrafters ad men. Over the next few years I hope to fully restore most of these nice old radios. Each restoration will be documented here, on my "BOATANCHORS" page.
The first restoration will be the original S-38, built in the late 1940's. I was able to obtain this radio from a ham fleamarket in Washington state for $25. I was delighted with the physical condition of the cabinet. There were no apparent scratches or scuffs to be found. The original S-38s were all finished with a heavy black wrinkle paint which (in comparison to later models using a non-wrinkle paint) has made these earlier models stand up very well over the decades. Not only were all of the knobs original but the radio worked as well! There were only two downsides, the first of which was the beat-up back and bottom cover plates, both made from a punched out cardboard material. The second was the BFO. Original S-38s boasted of six tubes, unlike all of the later five-tube models. Tube number six (12SK7) was relegated to BFO duty with a separate 'CW PITCH' control, which appeared to be non-functional in my radio.
Upon first inspection it appeared that the chassis would need a little cleaning. As well, there was evidence of an earlier attempt at restoring the BFO circuit. Several parts had been tack-soldered in place and it seemed that the BFO coil itself had been disturbed.
Although the cabinet and silk screening were in excellent condition, the back and bottom covers were not. In order to match the rest of the cabinet, these two items would need replacing.
The old back was used as a template to trace the shape on a piece of 3mm thick cardstock. The elongated ventilation holes were made by first drilling the ends and then punching out the straight sides with a sharp chisel. The back cover was finished with two coats of flat black paint. The bottom cover was made in a similar manner.
The original manufacturer's label was badly damaged so a replacement label was also made for the new bottom cover. Using Window's Paint program, a new "h" logo was drawn and incorporated into the label. The label was then 'antiqued' with the coloring from a spent tea bag.
The next job was to tackle the electronic restoration. All of the electrolytic and paper capacitors were replaced. New rubber grommets were used to replace the original rubber spacers that were used to isolate the hot A.C. chassis from the metal cabinet. All switches and pots were sprayed with contact cleaner and the main dial cord was restrung. As well, the BFO coil was removed and examined.
Although the schematic indicated that the BFO coil was a single tapped coil, it seemed that the actual coil had separate primary and secondary (tickler) windings. Numerous attempts at getting the BFO to oscillate were unsuccessful using various configurations of this coil. A call for help on the "rec.radio.amateur.boatanchors" newsgroup revealed a variant BFO circuit of the early S-38. It appeared that even the Hallicrafter's folks did not like this original circuit! The variant showed a single tapped coil and a different feedback arrangement. Accordingly, a new BFO coil was wound which resulted in immediate success and lots of oscillation on 456kc!
The new coil consisted of 200 turns of the original #32 wire, scramble-wound and tapped at turn #160. The entire coil was padded with 500pf to resonate at 456kHz.
After a light coating of 'Armor All' to freshen the wrinkle finish, followed by a quick alignment, the restoration was complete. The S38 is a sensitive little radio and even a small clip-on wire in the shop revealed plenty of signals both local and DX.
Now all I need is a nice suit!
S-38 SCHEMATIC - This is the 6-tube BFO model.
RESTORATION 2 - This page describes my first Hallicrafters S-40A restoration.