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UTC transformer help needed

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Posted on July 31, 2012 at 12:14:25
DIY John
Audiophile

Posts: 238
Joined: November 29, 2001
Folks,

I have a pair of interesting UTC transformers that I need information for. Any experts out there? I cannot find a listing in any of the easily found UTC literature, but I have likely only scratched the surface. Maybe they were special order or military?

The only markings are on the side: UTC W-1090, then a second line 706-105.

They are round, 2 3/16 inch diameter, 2 7/8 inch tall, with 16 terminals on the bottom. Resistance measurements show 4 windings, none identical. Weight is about 19 oz. They are similar in style to the RC-50 case shown in a 1953 catalog, but they are larger.

Any information would be appreciated. Incidentally, there is a non-USA e-bay listing for an amplifier that shows up when googling this. This listing indicates use for a SE OPT of 15K ohms to voice coil. If true, this could be a fun transformer for a low power SET.

I would really like to see a catalog listing or data sheet if anyone can help.

Thanks,
John

 

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Sounds Like a Desireable Tapped SE Opt to VC or Line..., posted on July 31, 2012 at 15:39:36
Interstage Tranny
Audiophile

Posts: 2751
Location: Eastern
Joined: October 4, 2006
Typical CG series opts have separate line secondary and voice coil secondary. The VC windings will be labelled A thru C or D on the normal CG trannies. The Line winding taps will read a few dozen Ohms to possibly over 100 Ohms; the highest DCR would represent the 600 Ohm winding.

As I recall with these versatile SE opts, they have a tapped primary winding. Besides DCR readings, LCR readings wil help you sort this out. Without an LCR, you will need to perform some troubleshooting tests with voltages in and measuring the opt; but you knew that...Fidelity is reasonably good with this unit; if it's the one I recall...

 

RE: Sounds Like a Desireable Tapped SE Opt to VC or Line..., posted on July 31, 2012 at 18:39:47
DIY John
Audiophile

Posts: 238
Joined: November 29, 2001
The A thru D terminals do correspond with the lowest resistance windings, so I would assume voice coil. Highest reading about 1.6 ohms with 2 additional taps.

I said 4 windings before, but there are 4 in addition to the VC, each with one tap (not at half resistance). Max resistance of each of these windings is 92, 634, 49, and 73 ohms. Any additional comments on these?

I have an LCR bridge, but it needs repair and doesn't read L right now. Plus I am under a bit of a temporary handicap with a lifting limitation imposed by surgery, so I can't sling around the equipment to rig up something to figure turns ratio.

I appreciate the good tips. The CG series case size of RC-75 does match up fairly well. I suppose it was too much to hope for a data sheet!

Thanks,
John

 

RE: UTC transformer help needed, posted on August 1, 2012 at 08:45:42
Alpha Al
Industry Professional

Posts: 2022
Location: N. Carolina
Joined: February 16, 2004
Contributor
  Since:
December 0, 0000
Probably a proprietary design, made by UTC for a particular manufacturer's product.

I have several vintage UTC catalogs, it is not in any of them.

Likely good quality.

 

RE: UTC transformer help needed, posted on August 1, 2012 at 09:27:11
DIY John
Audiophile

Posts: 238
Joined: November 29, 2001
Thanks for the input. Do you see any that are SE plate to voice coil? I was having a hard time finding catalog listings for any other than PP.

 

RE: UTC transformer help needed, posted on August 2, 2012 at 12:14:20
Alpha Al
Industry Professional

Posts: 2022
Location: N. Carolina
Joined: February 16, 2004
Contributor
  Since:
December 0, 0000
Yes, the S-14 is SE. Primary tapped for 2.5K, 4K, 7K and 10K. Secondary 500, 15, 8 & 2 Ohms. 10W power rating.

 

RE: UTC transformer help needed, posted on August 2, 2012 at 13:25:21
DIY John
Audiophile

Posts: 238
Joined: November 29, 2001
Thanks, Al. I see that one now. For some reason, I have a hard time figuring out their numerous product lines. They were certainly a prolific company!

I also managed to find some "Military" numbers beginning with a W, but these all had 3 digit numbers in the 700's (and hermetic, to boot).

 

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