I want a tube am/fm radio

Discussion in 'Amp Central Station' started by peteb, Dec 19, 2013.

  1. Prairie Dawg

    Prairie Dawg Tele-Meister

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    This is something I actually know something about, having collected antique radios for the last thirty years. The collection stands at about 300 sets at this point and it is what led me into my work fixing amps.

    If you can find an AM-FM table radio with a power supply good. They're not very common though, and you could do well to look at either Packard Bell or Gilfillan-both very well made west coast models. Also if you can get a Farnsworth AM-SW table radio they are among the best consumer radios ever made. If it's a series string set, just recap.

    What you will mostly see (in the US) is GE, Philco, or Zenith because they were the most common and also the best made, particularly Philco. Zenith was more stylish but not as solid. In Canada you will often see Marconi, Canadian GE, Northern Electric and many others we rarely see here in the states. I think Simpson sold under the trade name Serenader if memory serves me correctly. I don't know much about European or British radio sets except that my grandfather had a Grundig he was very fond of and it had marvelous tone and reception. I have seen Grundig, Telefunken, and Emud sets occasionally but they are not popular with American collectors. The only European radio I'd like to own is either a Bush, or a Volksempfanger-the German "people's radio" of the 1930s and 1940s.

    What you will also mostly see is AM and short wave, because foreign DX-ing on cold winter nights with a long line antenna up in the attic or out to the barn kept people in touch with the outside world in the thirties and, during the war you could listen to the BBC, Radio Moscow, and the Deutsche Rundfunk for levity and fantasy of a high order. Everyone in 1941 knew the Germans were going to lose the war eventually except the Germans themselves. The Volksempfanger was specifically built so as to not be well suited to receiving foreign broadcasts-information control was then as now governmental interest. If you were a German during those years and you were caught listening to the BBC, a jail cell or a bunk in a konzentrationslager awaited you as a subversive element. It is interesting in this context to read what Josef Goebbels had to say about truth being the enemy of the state.

    You can still have a lot of fun with those radios listening to foreign short wave news services although the internet is fast making that a thing of the past.

    The FM (frequency modulation) system was invented by Major Armstrong and resisted by RCA. Armstrong set up what he called the Yankee Broadcasting Network on 42-50 mhz and there were a number of BC stations on that band, Between Sarnoff and the FCC, they conspired to give that frequency band for television, thus putting Armstrong out of business or so they thought. The new FM broadcast band is what we now have, 88-108(?) mhz.

    You can find some Zenith radios from 1946 which have, in addition to AM, both the 42-50 mhz band and the 88-108 mhz band but they are rare and valuable to collectors.

    Incidentally after Sarnoff massively infringed Armstrong's patents and sold licenses, Armstrong committed suicide after assaulting his wife. She continued the litigation and won every damned lawsuit against RCA and its licensees. She used the money to restore the Hispano Suiza car that ARmstrong first courted her in in the 1920s when she had been David Sarnoff's secretary.

    You can read all about this in Tom Lewis' excellent book Empire of the Air, the documentary of the same name, and nuerous other interesting books such as Armstrong's biography and Gerald F.J. Tyne's Saga of the Vacuum Tube, as well as Hugh J.G. Aitken's "Syntony and Spark.

    I've never much dabbled with car radios except to curse the Sylvania engineers who developed Loktal tubes.:twisted:
     
  2. BobbyZ

    BobbyZ Doctor of Teleocity

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    Praire Dog, you ever work on a Grundig ?
     
  3. eugenedunn

    eugenedunn Friend of Leo's

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    1962 Telefunken Concertino 5384 W Radio

    Prairie Dawg,
    I enjoyed your discourse on the wonderful tube radios of yesteryear..... There were so many really cool AM-FM Shortwave European table radios created in the 60's. I was in Santa Barbara a few years ago visiting my college gals at UCSB, and went totally agog with awe over a 60's Telefunken Concertino 5384 W AM-FM-Shortwave model, I saw in an antique store. My wifey and daughters all noticed my fawning and drool running down my chin.

    They came back to that store at a later date and bought the dang thing and hid it somewhere for months..... then they bequeathed to me on my birthday! Dang, I was dumbstruck.

    It has the retro-cool blue EM84 / 6FG6 "Magic Bar" tuning tube....so flippin' cherry, Man!

    The radio functions work for the most part (even the tube FM stereo multiplex decoder attached to the inside back panel), but the volume is SO LOW.... I dunno if it needs a cap job or something like that?! I resolve to work on getting it serviced someday. Not sure who might be able to help me there. Anybody you know that can work on such a complex unit? As I said, the unit is pretty much functional, except the volume level is really low and the side speakers don't play....but everything lights up and there's reception on all bands.

    The thing even has DIN type jacks in the back to connect external speakers, turntables and other devices..... really a full-blown system.

    I have numerous gut shots and even a schematic / layout sheet for it....but man, it's a beast inside. (^_^) Here's some photos....
     

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  4. Octave Doctor

    Octave Doctor Tele-Afflicted

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    We had a wooden Zenith AM/FM with the circular dial--it already had a line in, so I just made a cable. Sounded better than the cheesy Norma guitar amp I started with.
     
  5. muchxs

    muchxs Doctor of Teleocity

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    I have. Mostly with a claw hammer 'cuz once that chipboard cabinet gets wet that's all she wrote. I think every Grundig in every basement in New England got wet during Irene.

    I've got what's left of a Majestic console and at least one complete spare chassis for your table radio. It may be spring before I figure out where I put it... :rolleyes:

    The hassle with Grundig aside from the overall oddity (compared to U.S. made radios) the hassle with Grundig is all those plastic buttons and associated switches. The ones I see have been rode hard and put up wet, recently literally put up wet. Seems to me the less complicated American table radios hold up better when they get knocked around.


    Christmas freebie... I have at least two tube tuners, Magnavox or Zenith or something. Anyone who wants 'em can have 'em for whatever it costs to ship 'em. They're heavy.


    I also have a Crosley chassis down the cellar with the tuning dial and the eye tube. It's all octals.

    I have a similar Philco chassis with the funky PT with the rectifier socket in the middle.


    I have 50L6 tubes for your transformerless junk. I probably have hundreds of them. If you can't find 50L6 tubes it's because they're all here. :rolleyes:

    The story on those: I was at an antique radio show. A vendor had a caddy full of tubes. I had a large bill. He didn't have change. I quickly scanned his table for a "mercy buy" and spotted a beat up cardboard box full of loose tubes. That took care of the change problem.

    An (only slightly) insane video tech from the New York metropolitan area started to rummage through my stash not realizing I had just purchased the whole lot. I let him go. He sorted out half the box. No big deal. There was nothing I wanted in his pile. He asked me how much I wanted for the 100 or so tubes he picked out. I shot him a price which is what I had just paid for the entire box. :D I figured he'd bargain a bit even though it was a dirt cheap nickel and dime price per tube. He chdeerfully forked over the cash and skipped merrily away with his stash.

    Now I have a big ol' pile of 50L6 tubes.
     
  6. printer2

    printer2 Poster Extraordinaire

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    It was one of my first completed guitar amp which I used to try out some ideas. Just basic P-P but using 12AQ5's with a 12AX7 and a 12AV5. Actually is Class A, can run SE by not driving one side. Rotary switch is crap and you have to play with it till the contacts make. Same with the small switches on the back for cathode bypass and NFB, they crackle. Some day I will redo the circuit without them. The wood section where the knobs are in went horizontally and the knob area was for the tuning numbers and the dial. There was another hole on the other side and they were used for volume and tuning. Grill cloth was trashed so I made this one out of a place mat and 'reliced' it.

    [​IMG]

    [​IMG]

    Those Philcos did get around.

    [​IMG]

    My version was only SE with a 6V6, used the PT for my Champ. Actually felt bad breaking up this cabinet.

    [​IMG]
     
  7. backporchmusic

    backporchmusic Friend of Leo's

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    Lots of good looking radios here. I'm not a collector, I'm just a listener, so brand/era isn't that important to me.

    For me, it's a thrift store find. I have a few of them, never paid more than $6. Nuthin' fancy, and they often require a bit of cleaning, but I love a little tube NPR while I'm working.
     
  8. Robster

    Robster Tele-Afflicted

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    As a kid of about 13 who was not afraid to tear anything apart and put it back together. I recall trying to find a place to wire my guitar into a nice old tube radio once.(I had a crappy solid state Teisco amp at the time). Turn radio on, start touching places I thought might make my guitar signal come thru....few trys later and BZZZT! Got a real nice shock. I abandoned that idea and put the radio back together...bad idea.
     
  9. Prairie Dawg

    Prairie Dawg Tele-Meister

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    My passion tends to bakelite table sets from 1936-1953 more or less which is why I'd like to get a Volksempfanger....they made bajillions of them. I don't buy too many sets any more but for that I'd make an exception. Sooner or later as muchxs says you run out of room though (if he said that and if he didn't he was thinking it), and I got rid of most of my radio parts and tubes a few years ago on the theory that if I hadn't touched in in three years it was going to the auction and if I needed it AES is as near as my computer. I have not worked on a Grundig but just from looking at them you gotta know what you're doing and have the technical information and test equipment to properly align them. FM is considerably more involved to repair and adjust than AM or SW. I agree that the American and Canadian made sets were in general better stuff, more durable and reliable than the European but less elegant.
     
  10. jefrs

    jefrs Doctor of Teleocity

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    I know it can be done because I have a colleague who builds fm and digital valve radios for a hobby. The digital radios do have a significant number of solid state IC components. But it can be done.

    But do note that fm radio broadcasting will probably be shut off in the next few years as we all go digital whether we like it or not, and like the way that medium wave am is going become as obsolete as long wave and short wave stations.

    I'd really like my big old stereogram cabinet back...
    I have two wireless radio cabs, one beaten up repurposed as a guitar amp, the other a beautiful restored stock cab 40s radio with a dangerous fault (live chassis, round tuit).
     
  11. jefrs

    jefrs Doctor of Teleocity

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    Wot! You too?

    Ow!!!

    Most ancient wireless sets had an input, ostensibly for a record player cartridge.
    Although far more modern, my olde Grundig Partyboy SS broadcast receiver still had that. Still works perfectly too.

    Mum's picnic box Bush record player also had connectors to run in stereo, that functioned as a guitar input socket for a small boy ;)



    * wot, to know, comprehend, familiar with, see the French connaître
    wot you = "I know you"/"I recognize you", corrupts to "wotcha", pre-dates "hello" ...
     
  12. peteb

    peteb Friend of Leo's

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    Thanks for the info.

    The main question is then wether or not to accept a transformerless model.

    Is a series string set a '5tube' amp?


    Seems like most tube radios are transformerless and its not obvious if they are unless it is obvious that a table top radio is transformerless just because of the size.

    On the one hand, transformerless amps are dangerous, on the other hand, playing a radio is not as dangerous as playing electric guitar.


    I now see the benefit of a wooden radio in that a much larger speaker can be used. The table top radio could be used with an external cab.
     
  13. printer2

    printer2 Poster Extraordinaire

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    The radios were not considered dangerous if they did not have any conducting components outside a non-conducting case. The wood or plastic knobs and cabinet took care of that. No different than an electric drill with a two prong cord you can buy at any hardware store. If you plan on using it as a radio and it function as designed you should be fine.
     
  14. Prairie Dawg

    Prairie Dawg Tele-Meister

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    Arvin (still in business) and known today as then for their metal stamping expertise made a lot of metal case series string radios with a baked enamel finish uner their own name and also Silvertone and even so you can feel the juice in them when they're running. Sometime you'll see one that somebody has stripped and chrome plated.

    Now that's a real death trap.:D:D
     
  15. telefunken

    telefunken Friend of Leo's

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    using a Tesla oscillator :rolleyes:
     
  16. jefrs

    jefrs Doctor of Teleocity

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    Yeah, about that. Ours have a three-wire cord. If you can touch any part of the chassis then it must be earthed. The chuck is effectively chassis.
    I've had these drills apart, the B&D has an earth wire screwed to the motor frame.

    As with a wireless set, if you can touch the chassis at any time, including around the back, then it must be earthed. If you are using it as a guitar amp then you are effectively holding the chassis.

    This comes from an international standard backed up by regional national legislation. The only time you get away with just live and neutral is if it is truely "double insulated" i.e. cannot touch any metal/chassis.

    The old wireless I have has a fault, the chassis goes live and fortunately blows the fuse. I haven't poked around much inside. It probably runs straight off our 250VAC mains and the OT is wrapped around the speaker, special name I've forgotten what they're called. I've been advised to gut it and reuse the chassis.
     
  17. BobbyZ

    BobbyZ Doctor of Teleocity

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    Sounds like a field coil speaker . It was also common to mount output transformers on perment magnet speakers when they first came out.
    But if the OT is wrapped around the voice coil I'd bet it's a field coil speaker.
     
  18. printer2

    printer2 Poster Extraordinaire

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    Separate OT as the coil around the speaker supplies the magnetic flux using dc from the HV supply. Quite often it is inline with the amp circuit and used as a choke for the power supply. They also may use a coil in the FC circuit in line with the OT to buck the hum from the PS ripple.
     
  19. keithb7

    keithb7 Friend of Leo's

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    Thanks for pointing that out Telefunken. I just did some Tesla research. Quite an interesting guy with some great, and weird too, ideas. Labled a mad scientist by some, he died alone in a NYC hotel.
     
  20. joeford

    joeford Friend of Leo's

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    i have one of these guys converted to a guitar amp (old white plastic GE)... been playing on it for a couple years here and there. the input jack is switching... so when the guitar is unplugged, it functions normally as an AM radio. the quality sucks... but if you're looking for an AM tube radio for quality, you have a few tubes loose anyways :p

    the transformerless design can be dangerous if you're stupid about it. i test it with a multimeter before picking up the guitar to make sure its working right... and i've never had a problem. if you're just using it like a radio, especially in a plastic case, they're perfectly safe. i think they sound great in their own way. reminds me of listening to baseball games with my grandma
     
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