1953 Tube radio turned into Amp

Discussion in 'The Workbench' started by Rotorcraft230, Feb 20, 2020.

  1. Rotorcraft230

    Rotorcraft230 Active Member Premium Member

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    7EBB5D54-EC77-4583-9C1D-B9FBA2352F5E.jpg 12737CD3-EB78-4806-BE6F-7A0AC239DFAA.jpeg EDC6C7C9-85B9-478A-AAB8-C1179EE095C0.jpeg Hello fellas, I found this 1953 Westinghouse tube radio in the trash and want to turn it into a mini Tweed amp. I was able to get it to work by putting the guitar input into the volume pot. My question is that the best place to do it? Here is a schematic it’s not the one I have but it’s very close. Mine is a H837L5 the schematic shows a transformer which mine dosent have. Thanks for looking.
     
  2. Ken Underwood

    Ken Underwood Well-Known Member VIP Member

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    As there is no mains isolating transformer, hot mains, then leave well alone.

    Not only no mains transformer but no output transformer so speakers will be hot as well.

    Trying to do what you intend to do could be lethal.
     
  3. Matthews Guitars

    Matthews Guitars Well-Known Member

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    Ken is exactly right. Put it back the way it was and sell it to a collector. This is not the project you are seeking. If it experienced just one critical component failure, it could kill you.
     
  4. SkyMonkey

    SkyMonkey Well-Known Member

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  5. Rotorcraft230

    Rotorcraft230 Active Member Premium Member

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    We’ll surely don’t want to get hurt. Thanks a lot fellas. Will put it back together, it’s not worth much I’ll just let it look cool sitting on my shelf.
    By the way there is a OT. It’s mounted to the speaker.

    cheers
    Mark
     
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  6. SkyMonkey

    SkyMonkey Well-Known Member

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  7. South Park

    South Park Well-Known Member

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    It has no power amp in it . No tone controls no tone shaping . But it looks kool
     
  8. Rotorcraft230

    Rotorcraft230 Active Member Premium Member

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    Yep cool for sure, radio and clock still work so back to being a clock.

    Thanks for keeping me safe!!!!!!
     
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  9. RLW59

    RLW59 Well-Known Member

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    There were a lot of cheap line-voltage guitar amps with similar sets of tubes. It's worth mentioning that if you ever run across an old guitar amp with 35w4 and 50c5 tubes, it's not safe to use in stock form. For people who don't know a transformer from a choke, the easiest thing to look for is 35w4 and 50c5.

    The first version of the Silvertone guitar case with built-in amp had a power transformer and a 6V6 output tube -- the second version was line voltage with no power transformer and 35w4 + 50c5 tubes.

    Some people dig line voltage amps and say there's a way to use an isolation transformer to make them reasonably safe. (I've never considered owning one, so I'm not sure how you hook up the iso transformer.)
     
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  10. Rotorcraft230

    Rotorcraft230 Active Member Premium Member

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    thanks good info, no mains transformer means it’s not for me. Not safe not good.
    Mark
     
  11. Gunner64

    Gunner64 Well-Known Member Premium Member

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    I have a whole pile of them of old radios like that in my garage. Slivertone, RCA, Mongomery Ward, Atwater Kent..ect..I probably have 30 or so that I've collected over the years. A few old console models too. I have often thought about gutting one and building a champ or similar amp inside, and not use any of the original radio. Most of The old radios are pretty common, and not rare.

    I'm not an expert on old radios by any means, but some are worth more than others, and most are not worth too much..
     
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  12. Rotorcraft230

    Rotorcraft230 Active Member Premium Member

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    The one I have is plastic and not in very good shape. Pretty much just

    “Shelf Art”
     
  13. Matthews Guitars

    Matthews Guitars Well-Known Member

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    Many years back, I bought a Harmon-Kardon Citation II all tube stereo power amp for 250 dollars. Some yahoo had drilled a hole in the chassis and tried to make a guitar amp out of it.

    Well, maybe that could be done well if you put some real effort into it. Stereo, two 6550s per channel, great transformers, solidly constructed, not a bad starting point.

    But in its simplified "just add an input jack to it" format, it was a failure as a guitar amp. I spent too much time and money on getting it restored, and the
    guy who was supposed to restore it never finished the job. Eventually I just said "screw it" and traded the partially restored amp off to someone who restores them for a hobby.
     
  14. Rotorcraft230

    Rotorcraft230 Active Member Premium Member

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    That sucks, I’d like to get into more of this I like learning new stuff but I suppose I gotta be careful. This thread is a prime example. Glad I ask about it and found out it wasn’t safe. Learning new stuff.
    Mark
     
  15. Gunner64

    Gunner64 Well-Known Member Premium Member

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    A Harmon Kardon Citation is a very sought after amplifier, and hugely regarded in the world of Tube HiFi, and designed by a guy who's a legend. Modifying that is very different than gutting a $45 radio. What a shame, I hate extra holes in any amplifier.
     
  16. Matthews Guitars

    Matthews Guitars Well-Known Member

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    Your radio is safe...as a radio. But connecting external devices to it with wires going into its circuits is not a good idea. Transformers perform two critical functions, only one of which is conversion of voltages from one level to another. The other is isolation. There's no direct connection between the power on the primary side of the transformer and the power on the secondary side. It's a critical safety device.

    Any technician who knows his business will use an isolation transformer when necessary while repairing equipment. If the equipment is not isolated already, with its own transformer, you use the bench isolation transformer so you don't DIE in the event of certain kinds of faults.
     
  17. Matthews Guitars

    Matthews Guitars Well-Known Member

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    The restoration that was in progress started with a teardown and weld-up of the added hole. It was my first restoration project, and I guess you could say that it led indirectly to my current hobby of doing intensive restorations of Marshall JMP era classic amps, with the big focus being on restoring the chassis to as it was when it was first made. Much welding, grinding, surfacing, and galvanizing goes into the process.
     
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  18. ampmadscientist

    ampmadscientist Well-Known Member

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    I was about to say...:nono:
     
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  19. ampmadscientist

    ampmadscientist Well-Known Member

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    The second problem you have besides electrocuting* yourself, and there is no earth wire, is that the audio only has 1 stage. It doesn't have enough gain for a guitar unless you preamp the signal first.
    * If you die, you will be immortalized in the Marshall Amp Forum Hall of Fame for extraordinary bravery in the face of antique radios. Be assured with the upmost confidence that you will not be easily forgotten.

    But, if you can broadcast AM from your guitar, then that's another story! Then it would have plenty of gain.

    [​IMG]
    AM transmitter kit $49.95
    https://www.tubesandmore.com/products/kit-pine-board-wireless-transmitter
     
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  20. Rotorcraft230

    Rotorcraft230 Active Member Premium Member

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    I like extraordinary behavior but not this kind.

    I know that transformers change voltage what I didn’t know was the isolation part. thanks Matthews Guitars!!!
     

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