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Determining amperage on transformer - Sparton 931
radiola
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#1

10-21-2015, 12:26 AM
This could actually be a question concerning any vintage radio. Usually, schematics show the voltage breakdown of the power transformer, but fails to tell amperage. I would like to have a power transformer built, but the builder wants to know amperage of each winding. Any help would be appreciated.
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Radioroslyn
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#2

10-21-2015, 06:40 AM
The simple answer is to add up all of the current used in you set. You can do this by consulting your tube manual to find heater currents and plate/screen currents. What is the set you are working on??

Terry
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radiola
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#3

10-21-2015, 09:03 PM
(10-21-2015, 06:40 AM)Radioroslyn Wrote:  The simple answer is to add up all of the current used in you set. You can do this by consulting your tube manual to find heater currents and plate/screen currents. What is the set you are working on??

Terry

Hi Terry. Thanks for your response. I know this is the Philco Forum. Most of my radios are Philcos, but this one is a Sparton 931 from 1929. I spent weeks repairing coils, resistors, and the like. Then I refinished the case. Then it failed the bench test by showing a bad transformer.
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Radioroslyn
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#4

10-21-2015, 10:13 PM
As Moe Howard would say "Oh a wise guy ay" Had to get a Spartan! As you probably know it uses odd Spartan toobs. Anyway what you are looking for is 120ac pri, HV 600v ct @120ma, 3v ct @ 8A, 5vct @2A, 5vct @2.5A
Good Luck
Terry
(This post was last modified: 10-21-2015, 10:14 PM by Radioroslyn.)
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radiola
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#5

10-22-2015, 11:56 PM
(10-21-2015, 10:13 PM)Radioroslyn Wrote:  As Moe Howard would say "Oh a wise guy ay" Had to get a Spartan! As you probably know it uses odd Spartan toobs. Anyway what you are looking for is 120ac pri, HV 600v ct @120ma, 3v ct @ 8A, 5vct @2A, 5vct @2.5A
Good Luck
Terry

Thanks so much for the info. Now I can get this transformer problem behind me. Yea, I got lucky as someone sold their Sparton 931 chassis with tubes cheap and another guy sold his 931 tubes cheap, so I'm okay there...hopefully. Thanks again !!!
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Tubesforme
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#6

10-23-2015, 03:43 PM
A while back Play Things of Past had this exact transformer for sale. It was listed under power transformers type 2 (Shown at the very end of the listing. Gary Schneider is very nice to deal with. Tubesforme
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radiola
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#7

10-24-2015, 05:39 AM
(10-23-2015, 03:43 PM)Tubesforme Wrote:  A while back Play Things of Past had this exact transformer for sale. It was listed under power transformers type 2 (Shown at the very end of the listing. Gary Schneider is very nice to deal with. Tubesforme

Did they have it listed as a Sparton transformer? If so, I think it's gone. 
http://www.oldradioparts.com/2a23efl.txt
http://home.avvanta.com/~genet/Pathfinder_8A.pdf
(This post was last modified: 10-24-2015, 05:49 AM by radiola.)
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radiola
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#8

10-27-2015, 08:05 PM
HV 600v ct @120ma, 3v ct @ 8A, 5vct @2A, 5vct @2.5A
350-0-350 @ 80ma

Now, 350-0-350 adds up to 700. The HV is 300+300=600 volts. The man who is going to rebuild me a transformer wants to know:
"Radiola, we can make a transformer that will mount right in your existing bell housing.Do you know which HV is correct 600v or 700v?"
 
I'm assuming the High voltage is 600 but why do we have 350-0-350. I must be missing something. Please advise. Thanks !!!
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Radioroslyn
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#9

10-27-2015, 08:14 PM
I was going by the schematic. It show the transformer 300-0-300 or 600ct. That will give you about 250-275vdc from the power supply.

Terry
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Ron Ramirez
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#10

10-27-2015, 08:15 PM
Since we're discussing a Sparton radio, I have moved this topic to Other Radios (Non-Philco).
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Ron Ramirez
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Radioroslyn
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#11

10-27-2015, 08:16 PM
Tnx!

Terry
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radiola
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#12

10-27-2015, 09:28 PM
(10-27-2015, 08:14 PM)Radioroslyn Wrote:  I was going by the schematic. It show the transformer 300-0-300 or 600ct. That will give you about 250-275vdc from the power supply.

Terry

Thanks for your assistance. I'm using your specs to order a rewind  Icon_biggrin
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  1. The PHILCO Phorum
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