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Old 25th April 2009, 02:25 AM   #1
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Question Identifying Stancor Power transformers

Hi again all ! I have a couple of Stancor power trannies, and was wonering if there was a source for identifying their configuration by model numbers. I have:
1- P-4078...this came from an old Allied phono/mic amp with 2 X 6V6s
2- P-4081...this is currently in a Heathkit A9C...not original though. As you know, the A9C had 2 X 6L6s...this amp is putting out about 526V at the plates and appears to be wired for EL34s.
As always, any/all help would be appreciated...thanks.

" You can't make chicken salad from chicken crap !" My Grandpa said that !
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Old 25th April 2009, 02:53 AM   #2
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Talking Update

Hi...an update to my previous post : the plates are running at 543 and 545VDC.
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Old 25th April 2009, 03:02 AM   #3
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Hi ,

Try here .

http://www.bunkerofdoom.com/xfm/index.html
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Old 25th April 2009, 03:08 AM   #4
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Default battradio

Hi...these pages are too small and unreadable when enlarged....any other ideas?
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Old 25th April 2009, 07:15 AM   #5
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Default Re: battradio

Quote:
Originally posted by bereanbill
Hi...these pages are too small and unreadable when enlarged....any other ideas?
Battradio-
Thanks for that very useful link.

They look (and print) fine in my computer - XP and Firefox-

Pg 8 of the 1948 Catalog
P-4078 350-0-350@70mA 5v3A 6.3v3A
P-4081 400-0-400@160mA 5v3A 6.3v4.5A

Cheers
John
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Old 25th April 2009, 12:21 PM   #6
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Unhappy VictoriaGuy

Thanks...I got it to work by opening the page in another window.
But now I am confused...if P-4081 1s a 400-0-400 tranny, how am I getting 545V at the plates? I tried it with 2 different meters with the same...or close anyway...results. Could both meters be that far off?
And battradio...yes, thanks. It is a very useful site...I have a bit of stuff I can categorize now.

Don't you wish those were the current pricings?
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Old 25th April 2009, 04:38 PM   #7
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Default Re: VictoriaGuy

Quote:
Originally posted by bereanbill

But now I am confused...if P-4081 1s a 400-0-400 tranny, how am I getting 545V at the plates?
That's 400V AC, once you rectify and filter it, the voltage will be higher! depending on power supply configuration, there will be some losses through a tube rectifier and other components. but for a rough idea for solid state bridge rectifiers i use 1.414 to get a rough idea of the voltage no load. so....400v x 1.414 = 565V if you have a tube rectifier you could lose 20 volts there easy...so 545v at the plates is spot on.
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Old 25th April 2009, 04:40 PM   #8
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Quote:
Originally posted by bereanbill
Thanks...I got it to work by opening the page in another window.
But now I am confused...if P-4081 1s a 400-0-400 tranny, how am I getting 545V at the plates? I tried it with 2 different meters with the same...or close anyway...results. Could both meters be that far off?
A

You need to multiply the power transformer's AC volts by 1.41 (square root of 2) to get rectified DC volts. 400 X1.41=565V. You are dropping 20 V in the PS. If you are using SS rectification, the startup voltage when the tubes are cold can be up to 565V. The can be an issue for electrolytic caps as you are probably exceeding the voltage rating (typically 400-500V)

EDIT: Sorry for the redundancy, zero cool and I were posting simultaneously....
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Old 25th April 2009, 04:45 PM   #9
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Default Re: VictoriaGuy

Quote:
Originally posted by bereanbill

But now I am confused...if P-4081 1s a 400-0-400 tranny, how am I getting 545V at the plates?
That's 800 VAC across the 'hot' secondary HV leads, more than enough for your 500VDC after rectification.
A transformer like this could also be described as Sec: 800v CT
John
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Old 25th April 2009, 07:52 PM   #10
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Lightbulb Zero cool, Boy Wonder, VictoriaGuy

Thanks a bunch !!! I am an unschooled, seat-of-the-pants, trial and error toobnoob...all this time I thought ratings were after rectification. I could never get the math right when figuring voltage dropping resistors. It all makes sense now...thanks for another breakthrough everyone. This is really beginning to be fun now....YOW!!!:


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