Vintage radio

[CBS240]

Hi

This is my first post in the tube forum, I have not had much experience with tubes although I do know the basics. I have an old radio that my grandfather used to use. He got it when he was about 9 years old and used it quite a bit. It is a Gerod, but I don't know were the model # would be located on it. I would like to get it to work once again, if possible. I think some of the tubes may have been replaced at sometime. There is one with a tested sticker with date...11/17/31. I believe the radio is older though. Anyway, here is a picture of it.

[CBS240]

I've searched around but can't seem to come up with any good info in it. Here is the inside.

[rcavictim]

That's a beauty. Do a google for the Antique Wireless Association (AWA). They have many members, some probably willing to help you out.

[CBS240]

And this is one of the tubes, they all apear to be similar type, with 4 pins, but of course this doesn't mean they are of the same type, or are they. I don't even know if any of them are good.

BTW, on the metel label inside with the patent and serial #'s there is a listing as "type M" if that means anything.

[CBS240]

Originally posted by rcavictim
That's a beauty. Do a google for the Antique Wireless Association (AWA). They have many members, some probably willing to help you out.

WOW...fast reply.

AWA eh? Didn't think of them.

Thanx

[Tom Bavis]

I see a plate that says "Neutrodyne" - there's a Garod Neutrodyne listed here, but it only has four tubes... http://www.nostalgiaair.org/Resources/161/T0000161.htm

[alexmoose]

Vintage radio is what I did before I got into the whole Hi-fi thing. and there are a few words of wisdom I can pass on to one who is about to start restoring old radios.

1. Replace all old capacitors, espiecaly those awful wax paper capacitors

2. Unlike Hi-fi, in olds radios, most NOS or paper-in-oil caps are just a waste of money, you're going to notice no difference at all in the sound fidelity on an old radio

3. whatever you do, don't touch the chassis when it is plugged in, I made this mistake in my very first few days, and it was very nearly my last mistake. Those old, cheaper radios have everthing grounded to the chassis including the AC line, so when you plug it in, 120v of potential builds up between the chassis and the ground, all it needs is a path to the ground

Could you post the tube #s? I want to see if it's anything I am familar with

[kevinkr]

I think this a battery radio, no line supply would have been used to power it.

Type M is this particular model of neutrodyne. The tubes might be good or not. I hazzard a guess there are probably a couple of 201/01 types in there. Common in old radios.

Antique electronic supply makes some power supply kits intended for powering vintage radios. see www.tubesandmore.com

I'm not familiar with this specific model, but most battery radios used either 1.5V or 5V filament tubes, B+ would be +45, +90V, +135V, any or all of these values might have been used. C- is the bias supply and typically ranged around -22.5V, but varied somewhat.

Unlike AC radios there usually aren't too many caps in these, they tend to be transformer coupled and use mica types in metal cans in the rf circuitry - in my experience these are usually still good. Paper caps are generally only found in the audio stages of these radios and as an occasional bypass cap.

Don't indiscriminately replace anything in this radio, and because of its age and relative rarity any parts that are replaced should be retained. Test it first, I have run across one or two battery sets that still worked ok without any repairs if they were well stored.

[rcavictim]

Originally posted by CBS240
Hi

This is my first post in the tube forum, I have not had much experience with tubes although I do know the basics.

It just occured to me that it makes sense then as you are doing, to start at the beginning!

Did you inherit the tabletop pedestal horn loudspeaker that this radio likely needs to be heard? I believe those were fairly high Z so don't expect to be able to put a modern 4-8 ohm loudspeaker on there and hear much of anything.

BTW I searched under vintage radios at ebay by chance out of curiosity about a weel ago and saw quite a few of the style radio you have, and their horns.

[CBS240]

OK, I have removed the back so the bottom of the chassis can be seen. It appears there are large coils underneath. Are these those awful paper/wax caps or inductors? This is completely foreign to me as this radio is older than anyone on this forum I would say...... since I have no documentation. It is obvious that it uses an external PS as there are wires from the back of the case labeled +B, -B, +A, +B DET, +B135, -C 4 1/2, A-C+, and B+AMP.