ID Question
 

Hi All,

I joined this forum to get info on the Sansui I recently purchased, and am amazed at the wealth of information I didn't know I needed to know! I got the radio pictured below as a housewarming gift a dozen years ago, it worked when I got it. I have no idea what it is and I've moved twice and haven't tried it since, is there anything I should do before trying it again? When I first got it my ex father-in-law looked it over and said it was ok to use (he's a retired electrical engineer), but I don't know now. Any information is appreciated!

Thanks,
Michelle:music:

Very nice-looking set. :thmbsp:

Before applying power to that radio the power cord needs to be checked for condition. If it is the original cord the chances are the rubber insulation is all crumbly under the nice fabric sheath. If the cord makes a lot of crinkly noises as it is flexed about then it definitely needs to be replaced.

Next would be to pull the chassis and check and see if the radio has been recently "recapped"--all electrolytics in the filter network as well as any tubular capacitors serving as DC blocking or power supply bypass....

Check out Thatch Ear's commentary on care of tube equipment at http://www.audiokarma.org/forums/showthread.php?t=778 to get a good idea of what the considerations are.

When I was a kid I'd plug something like that old radio in and study the results. As often as not the radio would actually play. But usually they would not play for long. I did take some precautions, however, and also knew to have my hand on the cord so I could yank it if things got too exciting.

Thanks for the link! I didn't understand it all, though. What's a variac? How does it work? I'm pretty sure the power cord has been replaced. I don't know about anything else. When I got it it worked fine, but like I said it's been years since I tried it. Is the number 28-10 275 on the back a serial number? The little window on the left says "Western Air Patrol". Where would I find the model information? Sorry I have so many questions. I'm fascinated by it but don't really know anything. I've replaced cassette belts, speaker/headphone jacks and stuff like that but that's about it.

Western Air Patrol was the in-house brand (manufactured by someone else) at BF Goodrich tire stores. The styling suggests mid 1930's. Post the tube types and perhaps we can ID the model number.

OK, where do I find that information? I don't know anything about tubes. Is it on the tube or the base? I'm not afraid to take stuff apart but I don't want to damage anything. :D

Could be engraved on the tube base, but more than likely, they're printed on the tube itself. If the tubes are particularly dirty, take care because those numbers rub off very easilly. There's also a chance there's a tube diagram inside the cabinet, or perhaps the tube types are handwritten on the chassis or stamped into the tube sockets. Proceed cautiously.

Hey, if this was easy, it wouldn't be any fun at all.

That's ok, I aint skeerd! Seriously, thanks for the warning. I worked with miniatures for years and am pretty meticulous. Did I mention I like to take stuff apart? Everything from clock radios to carburetors to computers, but I like it even more when it goes back together right. I'm always willing to learn something new. I'll look as soon as I have time, starting with a can of dust-off, and let you know what I find out. How do the tubes come out? Would I need to remove them to see the numbers if they're not on the tube? Wow there's so much I don't know! I can't wait to get home and have a look.

Hello,

Here is some practical advice regarding the tube identification.

First of all: be very careful, the tube numbers engraved on the glass
are easily erased. Better leave some dirt in place than be sorry.

Your radio has at least five tubes. From the rear, two are plainly
visible, and the three others are covered by metallic shields (and
they do have a top cap connector as well).

The tubes are simply pulled straight up, but it is best to grab the tube
by the black base, otherwise it may come apart.

I would advise you to start by identifying the two tubes that have no
shields. Just grab them by the base and pull straight up, being careful
no to hit the top of the cabinet. Just hold the tube in the light, and
you should see some faint numbering on the glass. It is likely that the tube
located nearest the side of the cabinet will be marked 80, or 280, or
something similar. The other one might be 41, 42, or something else as
well.

Keep us posted about this. Once you have made it with these two tubes,
you will be able to try the other ones. This will involve the extra steps
of disconnecting the top cap connector, and removing the shield. It
may not be possible to remove the shield completely with the chassis
in the cabinet, so you might have to take the chassis out. Good luck.

Anyone who sees something important I left out, your input would be
appreciated. Regards.

Just that it's real easy to pull the plate cap off of old tubes when removing the cap connector, thus making the tube a lot less friendly to re-use, if not destroyed. The glue holding it on has deteriorated from age, and only the wire connection underneath remains for mechanical (and electrical) connection, and pulling on the (possibly rusty) cap connector often breaks the wire. Broken at the glass, the tube is lost. Broken at the cap, it's still a pain to recover. A novice should be warned to use caution, experience will provide techniques for removing it safely. Others here may have suggestions for the best method.

You already mentioned pulling the tubes out by grasping the base, not the glass. Same rule applies up top.

Thanks for the info! Does anyone have any suggestions for removing these caps safely?

Look at the leftmost tube (from behind). You can see the fitting on
the wire is split, so you see the different colored metal of the tube cap.
if you can hold the lower part of the tube cap with fine tweezers and
press down GENTLY while pulling the fitting upwards, you should be in
business.

OK, hopefully I'll get home early enough to get started. Thanks again!

A few other ideas...

Unless you have a good way of remembering where each tube goes,
remove them only one at a time.

You will find that these tubes have anywhere from 4 to 7 pins at the base.
Two pins are somewhat bigger than the rest. In order to insert the tube
properly in its socket, you must locate the two holes that are bigger.

Good evening!

Good heads-up advice on the plate/grid cap situation! :thmbsp: You need to be careful. Sometimes I used to hammer a right angle on the tip of a jeweler's screwdriver to use as an aid in prying apart the corrosive marriage of the cap on such a tube... Just a thot.....

(BTW a lot of IF and RF tubes in these old radios used a tube that sported contact to their control grid through a top-mounted cap on the tube envelope. Also there are many power-handling tubes of the time that used such cap contact for anode connection. In the philosophy of those times there was a reason for each of these practices. Miniature tube designs have subsequently exploded such theories of the necessities of such practices.)

Here's hoping that you can once again hear program from your old friend.

I post that previous link simply because I now believe that is how old tube sets should perhaps be treated. It is a lot of work--granted.

As a kid I was into shortcuts, which was one of the reasons perhaps I got the dubious nickname "Dangerous Dave" back in the day. And such moniker has stuck through the years I must admit....

More recently than I care to admit I went into a radio shop here in Pittsfield, MA where I waited to be waited on. I have been shopping there for over 30 years, so I have an inclination to ignore the help and go and select from their inventory as I please. I know more where everything is than any of them that operate the place these days--including the owner.

OK, so I go in one day--only very recently--bear in mind!, and find that the owner's son has somehow snagged yet another radio console. The history of it is that the client gave it to my friend after digging it out of the attic where it spent the last 45 years or so...I look it over while he is blabbering on the phone. He is eyeing me as I explore this old set, and start to pull out a major mouse-nest of packing material and mattress stuffing from amongst the tubes on the chassis. I then reach for the power cord to this radio (obviously still in good condition as observed by me!) and plug it into an outlet, while watching the owner's eyes bug out while he talks with his customer on the phone. :D I powered the radio up. It lit all the filaments. And then produced a mild hum through the loudspeaker. I put a finger on the antenna terminal, and reached in and swept the tuning gang (the dial drive string being broken, obviating the tuning knob) until I got program from a local station. The old radio clearly bellowed out the play-by-play of a Yankees/Red Sox game. The owner of the store said I was crazy. I retorted with "You're just figuring this out, my friend!?" Again: That's why I'm known as Dangerous Dave.

I did know enough not to try to run that old relic long enough to see what would happen as the diseased and aged capacitors started to revolt at being suddenly pressed into use after their long nap...

You are better to follow the more cautious avenues as recommended by Thatch Ear in the treatises outlined by such sage of perhaps more sober mind...

The only thing I can say as observation of my still-daring tendency after all these years is to say that the child is the father of the man....and perhaps to beg your pardon as to the ramblings of a foolish old fart.... :o

Hey, feel free to ramble all you like! One gains wisdom by listening to old farts ramble :yes:. Ok, here's what I found: tubes, from left to right looking at the back are 57, 58, 2A6, 2A5, 80. I used a tiny screwdriver between the cap and tube to gently wiggle the caps off. They weren't rusty. Tube #3 was hard to remove, I don't know if I got it all the way back in. The tubes all have a silverish color to them, like a used flashbulb, does this mean they're bad? Someone fixed (?) the speaker cone with pink nail polish, not my favorite color. :no: One light bulb is missing. It doesn't look to me like any caps/resistors have been replaced, but I don't know. What do you guys think? Also, I don't know who put that wire on the bottom or why, it dosen't connect to anything on the other end. What are the other two wires coming out of the back for? And the knobs? I can take more pictures this evening if neccessary.

Thanks,
Michelle:music:

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.

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.

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.:D

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.

Thanks Tom! :D

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.

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

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

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.

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

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.

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.

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! :D