Another Mystery Radio - ID?
 

Here is another radio I'm trying to identify.

Tube lineup is 43, 6C6, 6C6 (?), 25Z5, and ballast. By the way, there is no eye tube. What you think is the eye tube is painted on the dial. I also think the dial doesn't go with this radio. This dial has 2 bands, but the radio only has 1 band.

Any help would be greatly appreciated.

I think its a home-made jobbie.....................................

Is that a plug in coil by the tuner cap? If so, it might have been two bands if you had the other coil.
John

The eye tube is painted on the dial? That's interesting. If this radio is homebrew as at least one poster here has said, I would think whomever built the set could have wired a real 6E5/6U5/6T5 or other magic-eye tube into the signal circuits (AVC line) and mounted the tube in the same spot where the painted-on "eye tube" is now. The filament wiring could be a problem, however, as this radio seems to have a series-string filament arrangement with a 25Z5 and a ballast tube. It may or may not have enough reserve to power another tube. Depends entirely on the total filament voltage of the entire string; if it equals the power-line voltage, it could work. On the other hand, this may be why this radio has a ballast tube -- to take up whatever filament voltage is left after the four other tubes. I'm not familiar with tubes such as 43, 6C6, etc. (these were before my time), so I don't know what the filament voltage was. I would guess six volts, but that's just a stab-in-the-dark guess that may be way off. Since this radio has a ballast, however, I would guess the total filament voltage of the entire string must be well under the line voltage, with the ballast, of course, taking up the slack.

As I understand it, ballast tubes were the predecessors of resistance line cords and, later, wirewound filament dropping resistors. Ballast tubes were also used in early television power supplies, as I read in an old TV service book years ago; many a house fire was started when a ballast failed and the set owner carelessly jumpered across the defective tube. This may have gotten the TV or radio working again, but such a dodge can and often did result in serious damage to the unit or even the house wiring. Case in point: There was an incident back in the 1960s in Cincinnati, Ohio, where a homeowner, tired of replacing fuses when his wife's kitchen appliances kept blowing them, finally went down to the fuse box and placed a copper penny behind the defective fuse. This restored the electricity, all right, but it also removed the protection the fuse afforded the line, eventually overloading the house wiring and starting a costly fire behind the walls.

Today's electric service panels, with their bolted-in circuit breakers, are incorruptible, since there is no way a homeowner can bypass them; all he or she can do is flip the breaker back to its on position when it trips--after removing the short or overload, of course.

The AC power cord looks as if it is frayed at the point where it enters the chassis. I'd replace it before doing too much more with the radio. Also, it looks to me as if there may be a quartz crystal (possibly a small FT-243) in front of the antenna coil -- strange for a broadcast/SW radio of this vintage, but if it's a homebrew unit just about anything is possible. That component could even be a capacitor. :scratch2: It's difficult to tell, even after enlarging the thumbnail.

Don't think it's home made. The cabinet has curved front, veneer, typical factory glue blocks inside. The coil is not a plug-in coil, it's a typical broadcast band antenna coil. The brown square object on the coil is a capacitor that isolates the the antenna wire from the hot chassis radio. The dial is calibrated for broacast band and for 1.6 to 4.5 Mc, on which there is not much today, but I see no band switch anywhere to get that short wave band. Many times simpler radios included that band because they could just select fewer turns on the broadcast coil to tune short wave. Sometimes the switch was on the back of the chassis. Tube shield (Goat shield type) missing on the first tube on the left, see the shield grounding clip at the base. I think this is a no-name drugstore or similar set. Underneath the speaker grill are two little nail holes: the name plate was probably there. Sets were rebranded for drugstores, dime stores, etc. in that way. I've got one a bit older myself with no name but the two little "snake bites" where the little tin name plate had been. The 25Z5 is the rectifier, the 43 the output tube (also with 25 volt heater), and the others are RF amplifier and detector/audio, 6 volts each. The total is 62 volts, with the remaining 58 or so volts taken up by the metal ballast tube. Incidentally, you can sand and clean up that tube and spray it with barbecue black paint to make it look good. It will get HOT in operation. It's a tuned radio frequency set, really intended for local listening.

Reece

Ballast tubes had, IIRC, an iron filament inside a hydrogen gas atmosphere. It was designed to vary in resistance enough over a range of powerline voltages, to produce a constant current thru the tube heaters in the heater string. Somewhat fancier than just a power resistor, and the manufacturer got to claim that an extra tube was used in the radio. Think they came after resistance line cords were banned.

I noticed that the eye pattern on the dial looks to be translucent green plastic. Maybe whatever set this dial came from used a light bulb, which varied in brightness to indicate signal strength. Maybe a small light bulb in series with the plate current in the IF (or RF stages if it's a TRF) tube stage (the AVC line would vary the plate current, and that variation would vary the brightness of the bulb. It would have to be a small bulb, though. Maybe the kind used in small flashlights?

An East coast independent; Ansley, Air King, Automatic or similar.

I think.

What year? Maybe 1934 or 35? Has a metal tube so it can't be much earlier than that. ST glass tubes so it can't be too much later.

The "newest" signal-handling tube in the set is the 6C6 which was introduced in 1934, but the ballast has an octal base; the first octals were introduced in 1935. I'm guessing '35 or '36; however some mfrs. kept using big pin tubes for a few years after octals came in.

I think somebody somewhere played with this set, too: it would take getting into the chassis to see if there's any sign of a bandswitch or another coil for SW, and any sign of a pilot light. Little TRF's like this didn't usually have any bells and whistles. The tuning knob appears to be connected directly to the tuning condensor shaft. The pointer would travel in an arc, and would not get anywhere near some of the dial calibrations. Some kid may have fancied up this radio to appear to have SW and an 'eye'.

The more I look at this I wonder if this was a factory-made hoax: to indicate the calibrations, the pointer would have to come out where the "star" is in the middle of the dial. But there's no hole there. The green circle has a blanked out triangle in the back so that if it were illuminated, it would resemble a tuning eye, but there's no pilot light, and no sign of one that I can see from the pictures, unless that's the top of one peeking out from behind the condensor rotor. Were they just "using up" that dial scale because they didn't have a standard one at the time?

Love to see under the chassis!


Reece

Here are 3 more pictures of this "radio".

The more I look at it I'm convinced that someone took a chassis, a speaker, and a dial and then shoved it into the cabinet.

The speaker is on extra long wires that are taped together.

One interesting thing - the chassis is copper colored. Yet the radio components indicate a cheap radio.

I picked this radio up a few years ago at a yard sale along with about 6 other radios.

What a piece of junk.

Ah there is the lamp holder. Really cheap radio!

I wouldn't write it off just yet, it can sound actually quite good on nearby strong AM stations. Most AM radios filter out audio reception above 5KHz, because of excessively narrow IF strips. But this radio has only two tuned circuits, and should allow the reception of the full 10KHz audio AM stations broadcast. Yes, AM radio channel separation is 10KHz, but not in the same market. AM stations use 20KHz of spectrum, for double sideband AM. The station 10KHz away from your local flamethrower will be extremely weak, and in a radio like this, not audible.

The volume control in sets like this are actually a combination of variable antenna loading, and RF stage gain (as a cathode resistor). The wiper is ground, one end goes to the antenna input, the other to the RF tube cathode. Turn the volume down, you are increasing the loading on the antenna, reducing the signal the RF tube is seeing, and also the gain of that tube also drops as the cathode resistance goes up. A lot of creative innovation went into the design of cheap radios!

Where this radio will NOT excel is as a DX machine. It's strictly a local station receiver.

It looks like the pilot lamp is positioned behind the "tuning-eye" aperture, and there is a masked off area at the bottom to simulate the open wedge of the display...what a hoot! The builder must have been chuckling when he did that.

I'd say get it safe to plug in (check & reform electrolytics, check line cord, look for smoked components) and then apply power. What's to lose?

--Bob

I have to make this even scarier.

This was the bulb in the lamp holder when I got the radio.

http://www.audiokarma.org/forums/att...3&d=1233709579

Looks like an old style series string Xmas bulb. C6 IIRC, about 12V, don't remember the current. It would glow reasonably well at 8V, enough to make a fake eye tube glow.

I'm surprised it works at all. I just took a look at the underside of the chassis; looks as if someone cut out most of the components.

This one may (and probably should) pick up some of the more common 50kW stations at night, such as KYW, WBZ, WLS-AM, WABC, WCBS, etc. in the east and KABC, KCBS, et al. if within 50 miles or so of Los Angeles, among others--I've heard the big 50kW east-coast powerhouses here in northern Ohio after dark, using nothing fancier than a cheap 6-transistor portable radio with a loopstick antenna.

However, I do agree that a radio with this simple circuit (not much better than a glorified crystal set) would fail miserably if one were trying to snag a 0.5-kW station in, say, Kansas while he/she was in Ohio, even if the radio were attached to a 50-foot outdoor wire. I once owned a Zenith integrated stereo system with an AM tuner probably not much better than the one being discussed here. It was so bad it wouldn't pick up anything other than local stations in the daytime, and even some of those weren't readable depending on weather (I was about 15 miles from Cleveland at the time); at night I was hearing SW broadcasts in the middle of the broadcast band.

I wouldn't be surprised if whomever built the radio we are discussing took his or her cues from Zenith of Korea or Taiwan (!), as the set looks as cheaply built as the AM tuner in my stereo system must have been. The digital AM/FM tuner in my present bookshelf stereo isn't much better; it picks up one local 1kW (0.5kW nights) AM station 5 miles from here at 560 and 1460 kHz, 0.9 MHz apart. The station's assigned frequency is 1460 kHz. The FM tuner is not that bad, but not excellent either. I am some 40 miles from Cleveland's FM stations; this tuner won't get any of them in stereo using a standard T-dipole antenna. I bought a Terk tower AM/FM antenna which works better, but when using the amplifier, I have to be careful not to run the gain control too high, or else it overloads the tuner something terrible--even in this moderate signal area just beyond the suburbs of Cleveland.

BTW, when did you move to Seattle? I ask because I looked at your listing on the Buckmaster ham radio callsign server today and found that WA2ISE is still listed as being in Oradell, New Jersey. Did you move west just recently? :scratch2:

Hah! I have a 1937 Magnavox 78 RPM table-top phono that has one of those in the pilot light socket...green bulb through a red/orange lens??? I haven't plugged it in yet to see the sickly glow...

That's too funny, jonboy, now you have to restore the unit!

--Bob

I've seen similar looking 120V bulbs used as the dial lamp in '40's and '50's radios with selenium rectifier based power supplies.

Not a good set for DX ?!? I was gonna offer to swap my EK-07 or one of the R-3XXs on it.... Seriously, I've found that a LOT of these seemingly "dead" otherwise less-than-stellar sets come alive if you give 'em a halfway decent antenna...I took my KIWA MW Loop over to a bud's house one Sunday after, he had a late '30s catherdral that he'd re-capped, changed a few tubes in, done eveything by the book, but it was still deaf as a hammer. We hooked the KIWA up to it, & it CAME ALIVE...Little one & two lunger local-service daytimers from way up in Virginia & Kentucky bloomed...It was amazing. I wouldn't let him keep my KIWA, but he did run a line from his house about 75' to a tree. His set sings fine now...

Invariably C6 bulbs were in an 8-lamp string. They were designed to operate at 14-15 volts.

I'm just here in Seattle on a short term job assignment, which will end next month. Then I'll be back to NJ.

Sounds like FM tuners I had back in the 70's. Ones with bipolar transistor FM RF amp stages in the front end. In one I changed the bipolar to an FET, and got the overload problems under control (when you're 14 miles line of sight from NYC's Empire State Building, where all the FM stations transmit from, you get a lot of signal). Though I later heard that I could have done the same thing just by increasing the current thru the bipolar instead.

I had several strings of these lights, and I usually added more bulbs to the strings to drop the voltage seen by each bulb. Or use a rectifier diode to make the line voltage "look like" 85V instead of 120V (half power, which is not the same as half voltage if the resistance is the same. It's V^2/R=power, and 85^2 = (120^2)/2