Zenith Trans-Oceanic Model B-600 (1959-1962)
Out of the sawdust rises a diamond…
Near the end of May, a friend of my family told me that he had an old shortwave radio I could have. I guessed that it was either a Hallicrafters boatanchor or a Zenith TransOceanic. I highly doubted that I would be lucky enough to get a TransOceanic. When I visited him, he uncovered a black, rectangular radio covered with sawdust. As soon as I saw the word “Wave-Magnet” on the top, my eyes lit up. It was a TransOceanic! I took it outside of the garage to look at it. Inside the case I saw the words “Model B-600”. The B-600 was the last tube model TransOceanic produced. It looked to be mostly complete: it had the WaveRod telescoping-rod antenna, the Wave-Magnet, the cord-reel, the and the knobs. The faceplate was uncracked, except for a barely-noticeable stress-crack near one of the screws that holds it to the case. It came with all the tubes, even the 50A1 and the rare 1L6! All that was missing was the front cover door (he later explained to me that it had been broken sometime in the distant past [probably around twenty years ago]), the knob “brights” (often missing), the suction cups (also often missing), the Wave-Magnet cord retainer knobs, and the owners manual. The leatherette was intact except for a rip along the top-left corner of the back of the case, but it’s small. The cord was held outside of the case, tied up and secured with a “ratchet tie”. I cut the tie, and let the cord slowly retract onto the reel. There was a lot of sawdust inside the battery compartment and on the chassis, so I used a blow-gun to blow the dust out of it.
Going out with a bang
He told me to turn it on, but I resisted, knowing that some parts may have gone bad. I resolved to not plug it in until I had the time to bring it up on a variac. Unfortunately, I didn’t make it that far. I decided to demonstrate it to my grandfather. I cautiously plugged it in, watching for signs of smoke as I turned it on. To my amazement, it played! After two or so minutes, I unplugged it. Later on, I decided to run it for longer. That turned out to be a mistake. After around 20 minutes of beautiful shortwave reception, I saw what I thought to be dust emerging from the sides of the bandswitches as I changed bands. It turned out that it wasn’t dust. A few seconds later, I saw a bright flash come from behind the tone switches. Fearing the worst, I unplugged it, whereupon a plume of funny-smelling smoke arose from the holes in the top of the case (I had the Wave-Magnet out of its storage position for better reception). My mother carried the smoking radio outside, where I examined it. Pieces of paper and foil around the edge of the chassis told me that an old molded-paper capacitor had blown out with a vengeance. Time to haul it to the technical high school I attend, where I repair things.
Cap replacement chronicles
While the chassis was being pulled out of the case, a small leadless color-coded capacitor rolled out from underneath the chassis, confirming my guess. It was a 600 volt- rated .047mFd molded-paper capacitor which had been blown clear of its leads. At first, thinking that the most this cap would ever see was 90V, I replaced it with a 200V-rated .047mFd mylar capacitor. Later, I discovered that it was a line-bypass capacitor that exploded. Line-bypass capacitors are connected across the AC line. Not only do they see 120V, they also see voltage spikes which are many times higher than 120V. To prevent any more fireworks, I replaced the 200V-rated .047mFd mylar capacitor with a 600V-rated .047mFd mylar capacitor. The radio has been working fine ever since. Someday I'll get around to replacing the rest of the molded-paper caps, but seeing as it's working, I'll leave it as it is.
I managed to replace the knob "brights" (available from Antique Electronic Supply) and the suction cups (semipermanently "borrowed" from my nonfunctioning H-500), but it was still far from complete, as it still was without a front cover door (I had received one from a member of rec.antiques.radio+phono during the summer, but it was unrepairable) and a set of wavemagnet cord retainer knobs. Finally, in late August, Peter Wieck, a member of the Trans-Oceanic mailing list, announced that he had a 600-series Trans-Oceanic that he was "parting out" (selling the radio part-by-part). I immediately requested the front cover door and wavemagnet cord retainer knobs. Three weeks and $19 later, I had the parts that had been long-missing from my B-600! I immediately attached the parts, and it now looks teriffic. Unfortunately, the front cover door, while in very nice condition, was missing the latch bail (a part which allows the front cover door to latch to the bottom part of the latch; being made of potmetal [a very brittle metal], they are often broken). Luckily, the beyond-repair door I had received months earlier had a latch bail. I removed the bail-less latch from the good door, removed the good latch from the beyond-repair door, and attached the good latch to the good door. After a hour of shining the latch with Gel-Gloss (the good latch was heavily discolored), it shines like new! All my B-600 needs is a manual. Reproduction manuals can be easily bought from Mike Koch and Radio Era Archives; all I have to do is get around to ordering one.
The Sounds of Silence
Unfortunately, the inevitable eventually happens: a part breaks down. On Friday the 13th, while listening to my favorite shortwave program ("Allan Weiner Worldwide" on WBCQ), my B-600 suddenly went silent. I was mortified. After all the work I'd done, why'd it go silent? It wasn't the selenium rectifier, since it had been running on batteries at the time. I had a feeling that one of the tube filaments had broken (the tubes in any Trans-Oceanic are in a series string, so the failure of one tube filament causes all of them to go out). I had a feeling that the filament of the 1L6 (the most expensive tube in the radio) had broken, but it later turned out to be the one half of the filament in the much less-expensive 3V4 audio output tube. Replacing it with a JAN 3V4 I had lying around solved that problem.
Selenium rectifier replacement chronicles
After I replaced the 3V4, I decided to use the B-600 to listen to "Allan Weiner Worldwide", as I do every Friday. It was operating on AC at the time. 40 minutes into the broadcast, reception suddenly faded out. I then switched bands to BC, where I still got reception. I then switched back to shortwave, where I got reception for a minute, but then it faded back out. After a conversation with Peter Wieck, it was determined that the selenium rectifier was failing. Selenium rectifiers are notorious for failing gradually over time. Their forward voltage drop increases to the point that the tubes stop working. As this happens, the increased resistance causes the rectifier to heat up, which eventually causes it to burn out. When this happens, it emits a highly pungent odor, and could also start a fire. Luckily, there is an easy solution to this, which is to replace the selenium rectifier with a silicon diode as well as a resistor (around 40-90 ohms more than the resistor in there, which is 130 ohms) to make up for the lesser voltage drop of the diode compared to the selenium rectifier. The selenium rectifier in my B-600 was to the point that the tubes had stopped working, but thankfully the selenium rectifier had not burned out yet. The diode should be a 1 amp diode such as a 1N4004, 1N1005, 1N4006, or 1N4007. As for the resistor, I have heard that it's more desirable to solder a 40-50 ohm resistor after the 130 ohm sand resistor in there (the sand resistor acts like a fuse) instead of replacing the sand resistor with a 220 ohm 5 watt wirewound resistor, but I couldn't find a 40-50 ohm resistor that wasn't as long as the sand resistor. I replaced the selenium rectifier with a 1N4006 diode and a 225 ohm and a 750 ohm resistors in parallel (calculates to 173 ohms). The result? It's much more sensitive, and a lot safer than when it still used the selenium rectifier. As a test, I used my freshly-repaired B-600 on AC to listen to "Allan Weiner Worldwide" (and called in to the station while it was playing [if you listened to his program on 10/27/19100, I was the one who called in and proudly announced that I was listening to his program on a Zenith TransOceanic]), and it worked beautifully the whole time.
Conclusion (for now)
When my B-600 is working, I get reception on all bands. Mainly I pick up BBC, along with many foreign-language programs. One of my favorite shortwave stations is not-so-distant WBCQ, located in Monticello, Maine. I first picked up the station with my Hallicrafters S-118 tabletop shortwave semi-boatanchor (I don’t think it’s heavy enough to hold down a boat ;-), and have also picked it up with my B-600. Reception is not always good, but I’ve managed to hear many stations. The 4-foot-high WaveRod really improves reception. I even built a makeshift battery pack for it, which allows it to be used in remote locations. It is 98% complete, but still needs to be electronically restored (which I will do when I'm more skilled in repairing old radios). Stay tuned!
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