Help understanding 14 tap UTC/RCA power transformer
« on: October 17, 2020, 09:58:23 AM »
I needed a 400 volt power supply, with a 6.3v heater tap. I picked up this multi tap transformer hoping it will do the job. After getting it home and really studying it, I realized there are some things I don't understand. Between pin 6 and 7, there is a symbol that I seems like it's a center tap tied to pin 9, but there is no tap between 6 and 7. Does that mean that pin 9 is the center tap for 6 and 7? That doesn't make sense to me because 9 is part of the 625V supply? Also, pin 12 is 1.5v, but it doesn't say what pin goes with that? I wanted to do a bridge rectifier on the 6.3V line, and I know the diodes drop the voltage, and I wondered if there is a way to add that to the heater line to help compensate for the voltage drop? Ultimately, I'm hoping to end up with in the neighborhood of 400V on the high voltage side and a 6.3V heater line, both bridge rectified. I'm using 47,000uf caps and 1.2ohm on the heater line.
« Last Edit: October 17, 2020, 10:02:24 AM by AardvarkBry »


Khron

Re: Help understanding 14 tap UTC/RCA power transformer
« Reply #1 on: October 17, 2020, 10:28:51 AM »
To me, it looks like there's one big secondary winding with multiple taps.

The 1.5v should (?) be between pins 12 and 11.

Can you measure any resistance between pins 6/7 and 9? That should show whether that is indeed connected internally as a (center) tap for the 6-7 winding or not.
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Re: Help understanding 14 tap UTC/RCA power transformer
« Reply #2 on: October 17, 2020, 10:38:02 AM »
6 and 7 read .1ohm. 6 and 9 goes back and forth between .1 and 0. As does 7 and 9. Also, 8 and 10 reads 215ohms, 8 and 9 = 100ohms, 10 and 9 = 115ohms. I'm wondering if 9 is a center tap for both the heater line and the 400 ohm line too?

JohnRoberts

Re: Help understanding 14 tap UTC/RCA power transformer
« Reply #3 on: October 17, 2020, 03:05:02 PM »
I needed a 400 volt power supply, with a 6.3v heater tap. I picked up this multi tap transformer hoping it will do the job. After getting it home and really studying it, I realized there are some things I don't understand. Between pin 6 and 7, there is a symbol that I seems like it's a center tap tied to pin 9, but there is no tap between 6 and 7. Does that mean that pin 9 is the center tap for 6 and 7?
That is what it looks like.  If pin 9 is at some elevated DC voltage pins 6 and 7 will swing + and - around that. 
Quote
That doesn't make sense to me because 9 is part of the 625V supply? Also, pin 12 is 1.5v, but it doesn't say what pin goes with that? I wanted to do a bridge rectifier on the 6.3V line, and I know the diodes drop the voltage, and I wondered if there is a way to add that to the heater line to help compensate for the voltage drop? Ultimately, I'm hoping to end up with in the neighborhood of 400V on the high voltage side and a 6.3V heater line, both bridge rectified. I'm using 47,000uf caps and 1.2ohm on the heater line.

looks like pin 12 is 1.5V relative to pin 11.

It might make more sense in the context of a full schematic... caveat I am not the tube guy here....

JR
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