[spierce328]

Hello. Would someone have the specs for this transformer. Philco 32-8131. Thanks Steve Pierce

[klondike98]

Welcome to the Phorum!

[spierce328]

Thank you. I'm looking forward to it. Steve

[Radioroslyn]

Hi Steve and welcome,
In rough numbers what you are looking for is something that can make 525vac ct @ 60ma the 6.3v @3amps. this was calculated from the schematic. If you don't have anything on hand have a look over @ plaything of the past.

GL



[edit: Terry, I added a link to Playthings of the Past to your post...klondike98]

[spierce328]

Radioroslyn .  Can I ask you how you made those calcuations.  The schematic I have is barely readable, and I can pick up very few clues.  

Good stuff. Thanks Steve

[klondike98]

you will find a schematic for the 41-250 that is probably better than the one you have (if you got if off of Nostalgiaair) at the audiophool site:
http://www.audiophool.com/Philco.html

You will need the DjVu reader plug in. A link is found on his home page: https://www.cuminas.jp/en/downloads/download?pid=1

[Radioroslyn]

Sorry it's a guarded secret, only us old guys know!!! [Image: http://philcoradio.com/phorum/images/smi...on_eek.gif][Image: http://philcoradio.com/phorum/images/smi...on_lol.gif]

It goes something like this. In your set you have nine tubes. To determine the hv current you need to know how much each tube consumes. Two of the tubes don't consume any hv current and those would be the 84 (it delivers the current) and the 7A6. So those don't count in the HV circuit that leaves the other seven.  The mixer, osc, if, and 1st audio are going to be abt 5ma each. The output tube are going to be much higher  abt 20ma each. Add it up and you get 65ma. Another thing to look at is the max current that the 84 can deliver spec is 60ma. Hv current calculation can vary as a lot is dependent on how much hv is applied to each tube and the amount - bias on the control grid. This will get you in the ballpark.

High voltage voltage can be figured by taking the dc hv at the cathode of the 84 and multiply X2. You've got 265vdc x2= 530v. I must have rounded down a little. So than = 530v center tapped (265v on each side of center).

Heater current. Most 6v tubes the current is 300ma but there are many exceptions. Rectifiers and output tubes generally are higher. In your set you have five tubes @ 300ma = 1.5A The 84 is 500ma and the 41's are 400ma ea. There are four lamps but only two are at one time so that's 150ma ea (if they are #47 bulbs). so add that up and you get 3.1A. Looks like 100ma got away from me on my previous post.

In the world of power transformers more current capabilities is better but not higher voltage. More current capability means a cooler running transformer.

[spierce328]

Geeze..... I didn't know there was going to be math !

... but seriously, that's a huge help.  Thanks You. You wouldn't happen to one that fits those specs would you ????

Thanks Steve

[Radioroslyn]

Here's one that's good eletrical match size wise it maybe a little big than stock.  https://www.ebay.com/itm/STANCOR-PC8420-...ctupt=true
A Stancor PC8404 is a good match it a little less current than the one above and it has a 5v winding which you don't need.

This is a good voltage match but current rating is abt 60% higher than you need. Size wise here's a diagram of it: http://www.hammondmfg.com/pdf/EDB270DAX.pdf Since it Hammond it's going to be expensive.

[David]

   
So folks can see what you are working on. David

[spierce328]

One last question. Do I need to increase the rated voltage a bit to allow for voltage drop under load. 

Thanks again Steve

[Radioroslyn]

You if you desire. Truth be told +/- 20 or 30 volts isn't going to make of  a difference in performance and the tubes and other part are rated high enough.