Category Archives: Antique Radio

Sprayberry Academy of Radio – Home Study Course,1945 edition

Finished scanning the Sprayberry Academy of Radio, 1945 edition of the home study course, generously shared by Dave Holder. Some of these weren’t scannable and a few were missing.

I was able to discover the names of the missing booklets from items that were listed on eBay. Perhaps someone else has these and can scan them for me (or send them to me for scanning and return by U.S. Postal Mail). To match, I’m using 300dpi scanning, greyscale. I can crop or cleanup as needed and put into an Acrobat PDF file.

Cosmic Stink

Last night, I turned on the Hallicrafters S-120 to catch some C&W music on AM.

Zortch! Followed by (smolder). And a great and unholy stench was unleashed.

It seems I’d left the old selenium rectifier in-circuit. Big mistake. I’d discounted the many comments by “The Elders” on regarding the failure mode of these old rectifiers. Never again. After using it for several months in the office, then occasionally at home, I can now say this: it may have been sitting in storage for 30 years, mean-time-to-failure (MTTF) is about a year.

And if you don’t know what burnt selenium rectifier smells like… you don’t want to.

Replaced the old selenium rectifier (which made a satisfactory ‘clunk’ in trash can) with a 1N4007 diode. Also replaced R21, a 33 ohm Fuse-Resistor which… had done it’s job by going not quite open, but to over 100k-ohms, with a 5 watt, 100 ohm resistor. This value put the DC input voltages at almost the exact levels indicated on the schematic.

Now I’m on a hard-target search for any remaining selenium rectifiers in any of my test gear or tube radios.

A New (Old) Drake R-4A

I was given a Drake R-4A Receiver! A local ex-ham was downsizing and wanted to make sure it went to someone (else he was going to throw it out). Went through the bandswitch which appeared to be the only thing to be cleaned. Superb receiver, so quiet. Now to see if I can acquire the accompanying Transmitter (T-4), Speaker (MS-4) and Power Supply (AC-3 or AC-4) can be found as cheaply.

TrueTone Portable

I took a part of my day off to do a quick redo of <a href=””>a TrueTone Portable</a>. Many thanks to <a href=”” target=”_blank”>Mike Stute</a> for giving me this one a couple of years ago, when I casually mentioned that my mom had had one of these.

Zenith Transoceanic – Y-600

Finished the <a href=”TO-Y-600_refurb.php”>TransOceanic Y-600</a>. This is a magnificent radio and turned out nicer than I could’ve expected. A fortunate turn on this model was that the 1L6 tube is in good shape. Although in fairly ready supply, the tube has reached ‘unobtainium’ prices, even though solid-state substitutes are available. In any case the 50A1 was replaced with a solid-state replacement, which provides very stable current and voltage regulation, which is a good thing given the expense of the 1L6 tube.

Hallicrafters S-38B

Finished the <a href=””>Hallicrafters S-38B</a>; it’s seen some daily use in my office at work. This is my first run-in with the AC-DC power issue and I found a way to route the power cord ‘HOT’ through the switch to eliminate (unless the house wiring at the socket is reversed) shocks from a faulty cabinet insulator.