• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Help deciphering an old choke (actually a vertical sweep transformer?)

thorpej

thorpej

AK Subscriber
Subscriber
Howdy folks...

I've got a couple of chokes scavenged out of an old 1960 RCA TV. One of them is pretty small, and measures 899 mH @ 120Hz on my Agilent U1732C. This smaller one I've found on the Photofact for the TV -- RCA 94341-15, rated at 600 mH @ 270mA, DC resistance 46 ohms. I figure this could come in handy in a pre-amp power supply or something.

The other has a configuration I've never encountered before. It has 3 leads (black, red, yellow) all seemingly on the same winding.

DC resistance:
  • Black - Red : 258 ohms
  • Black - Yellow : 264 ohms
  • Red - Yellow : 6.4 ohms
Inductance @ 120Hz:
  • Black - Red : 9.2 H
  • Black - Yellow : 12.1 H
  • Red - Yellow : 314 mH
Numbers stamped into the frame of this odd-ball are hard to read under the varnish... at first I thought they read "01422-4 172 6212"... but then I found a reference to "961442-4" in the Photofact, and if I squint real hard at the numbers on the frame in the sunlight, it looks like that's probably what's stamped there. In any case, this part is listed under the sweep circuit transformers table as the vertical output transformer, with replacements being the Stancor VO-119 or the Triad A-131X.

I haven't yet found the part in the plethora of schematics in the Photofact for this particular TV set (KCS136YT), and I'm not particularly well-versed in how TV sweep circuits worked... nor have I ever encountered a transformer that measures like this.

I guess I'm wondering, could this be used as a relatively high-value filter choke?

EDIT: AH! I found it on the schematics. Snippet attached. So, I'm not crazy, it's drawn as I measured. And I guess it's blue, not black :)
 

Attachments

  • IMG_4872.JPG
    IMG_4872.JPG
    111.1 KB · Views: 20
  • Screen Shot 2017-10-06 at 3.01.47 PM.png
    Screen Shot 2017-10-06 at 3.01.47 PM.png
    74.5 KB · Views: 21
Last edited:
Register to hide this ad
The yellow would provide some out of phase output, not sure where that goes to in the circuit but it might be used for some sort of noise cancellation. AA5 radios did that with the output transformer, the out of phase connection went to the screen of the output tube to help hide the fact that the power supply was horribly filtered.
 
Yes, it's designed to carry DC, with a gap in the core. Should be good for 60 mA or more. (would dissipate only 2.6W at 100 mA, but may saturate at that level)
 
They would be good for a preamp or the screen and front end supply for amp amp , using it as a second choke
 
You must log in or register to reply here.
Back
Top Bottom