ID Question

[radiotvnut]

The silver color of the tubes is normal and does not indicate that they are bad. Looking at the pictures, I'd say this radio has not been re-capped (at least not in many decades). For best performance and for safety reasons, it should be re-capped. I don't know what that wire bundled up under the chassis is for; but, the wires coming out of the back of the radio are for antenna and ground connections. Most of those old radios from the '30's do not have built in antennas and require an external antenna for reception. Usually, a six foot piece of wire will work for local stations. From the tube numbers, I can tell that they use 2.5 volt filaments. That means that this radio was probably made prior to 1935. Somewhere around '35, tubes with 6.3 volt filaments replaced the 2.5 volt tubes.

[radiotvnut]

Those knobs on the back are likely for tone control and band switch. Many of these old radios had some form of short wave band in addition to the standard AM broadcast band.

[racerchick21]

Thanks for your info! I was told when I received it it was a 1928 model. How do I tell which wire is ground and which is antenna? What do you ground it to? I think the wire underneath can be removed, since it dosen't go anywhere, but I was wondering why it was there. I'm trying to identify this unit in order to get a schematic before I attempt anything like re-capping.

[Tom Bavis]

I'll look up the tube list in the Mallory manual under Western Air Patrol - should narrow down the model. Those tube numbers weren't around in 1928 - maybe 5 years later. My website is down or I'd give a list of tube introduction dates.

[racerchick21]

Thanks Tom!

[radiotvnut]

The ground wire will usually connect to the chassis and the antenna lead will connect to an antenna coil. The ground lead can be connected to a cold water pipe or to a metal rod driven into the ground. You probably won't need to ground your radio for local reception.

[ekimetsok]

Based on the tube lineup, your radio is Western Air Patrol's "Five Tube" (That apparently is the model name!) Here's a road map to what's going on under the hood:

http://www.nostalgiaair.org/PagesByM...7/M0023577.pdf

[racerchick21]

Thanks for the link! Too bad it's not a little better resolution, though.

[electroking]

Wonderful service data! They even tell you how to build your own
VTVM to measure AVC voltage! Of course a modern high impedance
multimeter will do.

Just as a sidenote, this radio is about as modern as a 5-tube AC
operated unit could be in 1935. It does not appear to be multiband,
from the looks of the dial and the absence of band switches on the
schematic.

correction: it could be multiband after all, there seem to be some
switched coils in the upper left area of the schematic. To be investigated.

[racerchick21]

Well, there's only one set of numbers on the dial, but there are two knobs on the back that aren't labeled.

[kbmuri]

The wire underneath doesn't belong. It's not even the right kind of wire for a radio of that era. If I were to jump to conclusions, I'd say someone tapped off the audio out for feeding into some other appliance with a larger amplifier. Or possibly as a signal-in from a phonograph, to play it through the radio speaker. Or possibly somebody retarded made a guitar amp. I'd remove it immediately.

The markings on tubes this old are sandblast-etched into the glass and will withstand being cleaned up. Windex is fine, or just water. Dampen a paper towel just a little and rub. No need to soak anything -- water and electricity never did mix. The results will be most pleasing. Nothing makes an old radio chassis sparkle like clean glass, and baking old dust smells bad too. Keep a black sharpie with you in case the number does rub off, but it really won't. If it does, clean one tube at a time and write the number back on when you're done.

You haven't mentioned whether you can test the tubes individually. If you don't have a tube tester, you might try the next local radio-club meet or hamfest, you might be able to test them there. Or there's always that eBay place if you want to own one yourself. Most of the tube testers out there don't test tubes that old though, so keep that in mind -- you'll have to find one that does. If any of the tubes are bad, the same places can get you replacements, still. Or some online stores still have them, but usually they cost the most there. If you really love the set and want to keep it around forever, buy a complete set of NOS tubes anyway and have them around for later. You can "test" the originals by swapping them with new, one at a time, and sensing changes in the radio's performance. If there's no other easier way to test them.

If you have a shop-vac or vacuum-cleaner that optionally blows air, take the radio outside, remove the tubes and blow a strong blast of air over the dusty top of the chassis, while simultaneously gently scrubbing it with a disposable toothbrush (you won't want to use the toothbrush for its intended purpose afterwards). The caked-on dust should blow off with some gentle prodding from the brush. Don't use water here -- seems like getting the old dust wet just makes it sticky and more permanently engaged. And what I said about water and electricity, too.

After brushing the chassis and windexing the tubes, you'll find a new enthusiasm for the rest of the job. The cardboard capacitors look original and doubtless no longer do their job. I'd start there. After testing the tubes of course. With tested/new tubes and fresh electrolytics it will most likely play again. The smaller wax capacitors, if bad, will cause sound problems or tuning issues or questionable reception, but they rarely cause a radio to not work at all. Save them for later. Sometimes the resistors will degrade too, but not as likely. Very rarely some other component.

As long as it's fun, enjoy the challenge.

[electroking]

The schematic gives R8 as volume control and R11 as tone control. I bet
the rear control with a round housing is the tone control. Also on the
schematic, you can read near the little drawing at the bottom:
Triplett Mfg Company Switch (unreadable). This is described
as a Hookup for phonograph. I guess this is the other rear control,
however I don't see an input connector for that phono.

Concerning the tube number etchings, kbmuri is possibly right, but
remember that some of these tubes may be more modern replacements,
so be careful when you rub them.

Good luck with the project.

[racerchick21]

Thanks everyone for your input and insights! It appears that some of the tubes are original and some are newer. I don't have anywhere to test them at the moment, but I will start cleaning it at least. I don't see anywhere that you could connect a phonograph, but I'm not sure how they connected them back then either. Maybe that black wire is a replacement for the original connection? Who knows. If anyone knows somewhere I can get tubes tested in the Reno, NV area, please let me know. Thanks again!