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Connections? UTC CG-59AX




 
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Author Topic: Connections? UTC CG-59AX  (Read 3058 times)
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KA8WTK
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« on: January 07, 2007, 04:12:34 PM »

The push-pull 812 transmitter restoration is coming right along. I am now working on the Class B modulator deck. The deck uses a pair of 811a triodes and a 300 watt Stancor modulation transformer. Bias for the 812's is also found on this deck.
The grids of the 811a's are connected to a UTC CG-59AX audio transformer. This is listed in the old UTC catalogs. What they don't show in the catalog is the pinout of the connections. I do not think there is a way to connect this in a manner that will allow an 8 ohm input from a HI-FI amplifier. But, I would like to confirm this before changing it out.
Does anyone have a connection diagram for this transformer?

Thanks! Bill KA8WTK
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Bill KA8WTK
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« Reply #1 on: January 07, 2007, 07:39:51 PM »

Darn! Can't type!

The transformer is a UTC CG-59AX (Despite what I may have typed before.)

Bill
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Bill KA8WTK
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« Reply #2 on: January 08, 2007, 09:15:35 AM »

Bill,
     Most grid input transfomas from thet era are typically something fairly high Z input, or 600 ohm line. If you want to feed it from an external amp, why not just take a regular push pull outpoot transfoma and just hook it up backwards in place of your utc unit?? Although a pair of p-p 811s only needs a few watts to drive the grids even in class b as they are high mu triodes.
   
                                                                     The Slab Bacon
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KA8WTK
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« Reply #3 on: January 08, 2007, 12:37:02 PM »

Hi Frank,
  Yep, I agree with the "backwards" output transformer idea. I use that on two other rigs already. I was trying to determine if this one would work and/or if it is really setup for 600 ohm input. If so, I have a Gates microphone pre-amp unit that just might have enough juice.
  If I can't get a pinout for the xformer, I'll just try it when I get to the testing phase with the Gates amp. If that setup won't work, we'll switch it out.


Bill
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Bill KA8WTK
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« Reply #4 on: January 09, 2007, 05:57:44 PM »

CG-59AX is a "Varumatch" driver transformer.  Primary is 50, 200 or 500 ohm line.  Secondary is for PP 805's, 838's, 203A's, 100TH's, 800's, 55T's or RK-18's as modulator tubes.  If your amplifier has a 70 volt line output, you could use that to drive the 500 ohm tap.  Sorry, I do not have the pin-outs but one should be able to determine that with an VOM.
Larry W7IXZ 
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