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Antique Radio Technical Forum
Stewart Warner R-149

Posted by resistor sub on 07/08/2009 06:12

:It's hard to read - I can't read the resistances any better than you can. But, my guess would be the same. Note that the resistances are specified hot; they would be less when cold.
:
:If the field coil on just one speaker is bad, no sense replacing both, right?
:
:Power supply chokes are usually specified by their current rating and there resistance. Your replacement should have a current rating of at least the maximum current through the coil. You can figure that by adding up the plate currents, etc., from a tube manual.
:
:The coil resistance should be equal to the original. You can pad it with an extra power resistor if necessary. Figure power rating by I^2R and doubling for safety. After replacement, check the B+ voltages, especially since there is some uncertainty in reading the schematic. Trim the dropping resistor if necessary.
:
:The inductance of the choke isn't critical.
:
:You could forget the choke for the time being and just replace the field coil with a power resistor, and jack up the value of filter caps #93, #57, and #40 by 50-100%. That likely could give you acceptable hum.
:Doug
:
::All right, guys: I will give up on the idea of repair. Now, the next question is can any of you tell me the resistance measurements for the field coils in this radio? I have enlarged the schematic and it looks to me that the 12" speaker field coil is 1100 ohms and the 10" is 4050 ohms. Does anyone have a better copy to verify this? I have read about the problem of increased hum when the EM speaker is replaced with a PM one due to the loss of the choke function of the field coil if one simply puts a resistor in it's place. So I'm assuming a better option would be to use a choke and a resistor (if needed to get the right resistance. Can anyone recommend a specific choke either from radio daze or AES? Thanks a lot. Mark from Kalamazoo

Here's the finished Bendix radio that I posted last week only as a Bendix chassis getting a rusty restoration.

My painter/collaborator Ken dropped this cabinet off the other day and I just completed the re-assembly.

I asked Ken to use some browns and reds with a twist. So he came up with a nice mix of metallic colors in Placer-Gold, Root-Beer, and Dark-Chocolate. He embellished the grille bar edges once again with that very attractive Brushed Silver effect.

I am very pleased with this color combination as I feel it fits in well with the period.

I feel it has a very attractive classic feel about it.... and so I'm expecting it to be received well.



Stewart Warner R-149 
Mmakazoo 07/02/2009 19:59 
Doug Criner 07/02/2009 23:12 
Marv Nuce 07/03/2009 00:27 
Mmakazoo 07/05/2009 14:35 
Doug Criner 07/05/2009 15:20 
Bill VA 07/05/2009 20:07 
Doug Criner 07/05/2009 20:21 
Bill VA 07/05/2009 21:17 
Doug Criner 07/06/2009 10:23 
resistor sub 07/08/2009 06:12 
Ian 07/09/2009 00:44 

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