My First Zenith Trans-Oceanic!
 

Greetings Everyone, today I just picked up a 1950 Zenith Trans-Oceanic Model G-500 for $49 at a local antique mall/flea market and its in really nice shape yet, the only thing wrong with it that I can see of is that the dial string broke, but other than that it still has its original Zenith badged tubes in it yet and has the original rod antenna (the one you pull up on and it extends like 5 feet into the air) and it also has the old Long Distance antenna intact as well including its original suction cups for mounting it to a window (the only thing missing is the antenna connection wires for the Long Distance Antenna).

I haven't had a chance to test it yet to see how well it works (if it needs to have its filter caps replaced or not).

Its even got the Copper Chassis which is in excellent shape yet.

Any tips or tricks for a first time user/owner of one of these Old Zenith T/Os?

Thanks for your help.

I'll upload some pictures when I get some time later.

I have a 1952 H500. I replaced four of the 5 tubes with semi-conductor replacements. The idea was to cut power consumption and lengthened component life. These are still available. The last tube is used to narrow IF response for better reception. I plan on having the selenium rectifier and capacitors and worn resisters followed by a tune-up. This is a good radio and can be surprising at times with strong reception and good fidelity. After this my 7000 will be "gone over" and realigned. You do what I'm doing and you'll get the best performance and longest life. Oh, I need a battery pack to see how well she sucks juice.

The filaments are series string so you can't really reduce heater power by using only solid state replacements... you'll either reduce power to the remaining filament or not achieve power consumption reduction.

In pretty much all tube portables the B battery asts the shelf life of the battery and the A (filament) battery is what gets spent quickly.

My understanding though is that the later tube battery sets had much better "A" battery life span than the earlier ones did like my Coronado 630B for example that used the old 2.1 Volt tubes vs. the later 7 pin miniature tubes that ran at 1.5 volts, like this Trans-Oceanic uses and has much less current draw.

A word of caution when when running the radio on AC - never, ever pull a tube and re-insert it while the set is on. Since the filament string is fed from the B+ supply, the filter capacitor across the string charges up pretty high and can blow the whole string (unless the radio has been modded with a Zener across the string for protection).

Also, if the set uses a 1L6 tube, treat it like gold cuz it's nearly unobtainable and gawdawful expensive. For testing purposes, TO gurus often sub a 1R5 which is common and 'waay cheaper but lacks performance on the SW bands.

I have had several Zenith T/Os, among them three solid-state versions. The first two now have broken dial cords and are now in storage, while the third one is still in use here and works very well. I have had a liking for Zenith radios and TVs for years, and have had several Zenith TVs, among them a Zenith 19" color table model (model SMS1917SG).

Most of the Zenith TVs are gone (I got rid of them when I moved here over twenty years ago), but I kept the 19" SS color set and several SS Zenith portable radios. The one Zenith SS T/O I have that still works is an AM/FM/SW set which works very well, especially on FM and SW; it gets stations on both ranges (this T/O has several SW bands) like crazy, just using the built-in 5-foot whip antenna.

For some reason, however, the AM broadcast band on this set is dead silent; it has been this way since I got the radio (it was an eBay score several years ago). I haven't yet figured out what the problem might be, although I'm thinking it may be an open oscillator coil.

BTW, I agree wholeheartedly with the advice not to pull any tube from a tube-type Zenith T/O while the radio is still operating and/or plugged in to AC power. This could damage the tubes, not to mention other parts of the radio; as old as these sets are, many if not most of the components could be difficult or even impossible to find replacements for.

My 7000 T/O had an AM failure due to a bad transistor. They're socketed!

Here's an excellent treatise on TOs, with some arcana on the 1L6 tube. http://www.zenithtrans-oceanic.porta....co.uk/1l6.htm

But there's an error in the second to last paragraph:

...1U6 is a 25 ma tube instead of a 50 ma.This means that it will test identically to a 1L6 in a tube tester but when placed in a radio, nothing will happen since it has double the filament resistance and the TransOceanic uses a series filament string.

The bolded line should be corrected to read:

"You'll blow the filament since doubling the resistance will double the voltage appearing across it." Probably not an issue though, since 1U6 is even rarer that the 1L6.

Sockets on TO's were trouble. Put a few drops of cleaner in it & put the
transistor in & out a few times. May get lucky.

I got it going! All I had to do to it was restring the dial string going from the knob to the dial, and then fiddle around with the push buttons, and it works great, not even any 60 Cycle Hum, which is amazing because its working on all original parts, including filter caps and bumblebee caps.

Thankfully it seems that no one tweaked around with the alignment! :thmbsp: :music: :banana:

:sing::rockon::yippy:

I wouldn't keep running it like that. Start with the electrolytics and then the bumblebees, a couple at a time and retest. I think that set has the multiple tap resistor that likes to fail too. Doing a decent job of cleaning the band switch is a PITA. You can also buy a solid state 1L6 for test purposes if you want o save the real thing.

Replacing the aforementioned parts is highly recommended. I saved my 1L6. Don't forget replacing selenium rectifiers using a dropping resister!

I think I may have a 1U6 in my tube stash. Aside from the heater* is it compatible with the 1L6 and capable of opperating on SW?

* The heater could be worked around with a parallel resistor to increase the current draw to match the 1L6.

Be sure it's not mistaken for 1U4 or 1U5 which are different critters.

According to the posted article it is. But I can't verify it, and online info on it is scarce.

The paralleled resistor (same ohms value as the filament when hot) does not increase current draw (which is a constant 50 ma.) but splits it in half for the tube. Remember that in a series circuit, current thru the whole string is constant. Whereas in a parallel circuit (imagine 6V paralleled heaters), voltage is constant across the lot. Series = constant-current, parallel = constant-voltage.