The AM Forum

Posted this on another site without much luck I'm trying to find out the spec's on a Stancor 24255 transformer. I know the voltage output is 4k or 2k, but have no idea what this transformers current spec's are. Hoping someone may have an older Stancor catalog in their files that may list this transformer. So far I've come up nill in my search.

Dave.

Five digit part numbers are specials.  It's not going to be in any of their catalogs.  The xfmr was made special for an OEM.  Most you can do is to estimate the current capacity by its weight and size.  You can load it down to some amount of estimated current and check the temperature rise.  If it doesn't get too hot, you're not overloading it.

Fred

I've mentioned this technique a on AM fone a few times before.

Make a semi- log plot of voltage sag vs. current or load resistance.  You'll get a decent load  line connecting the points until a noticeable droop at high loads, saturation limit sort of.

A sheet of three cycle semi log paper is the fastest way to record. Nowadays one could set up an Excel, tm., spread sheet with semi log graphing of the elements of course.

I was fortunate to have a very large, about 200 watts, center tapped 25 k ohm resistor.
That gave me 25k, 12k and 6.25k loads by clip leading various combinations, full body, half body and halves paralleled, etc. For short measurement times, the resistor warmed only a little.  You lay this out on a non-conductive surface such as a sheet of dry 3/4 plywood, and be very careful with lead dress, component spacing, component temporary mounting, etc.

I've done this with a ful wave DC rectifier board and filter caps following the ' unknown ' Xfor. too.
I'll go see if my iPad will capture a pix of a couple of transformers I'd done in the past using this technique. One was a 1600v ct plate Xfor rated at 500 ma along with PDahl 3000v at 1A on same sheet.

With modern bolt mountable resistors, one could rig up a heat sinked resistor bank with say a 2k ohm , 8877 plate load representation and see what a given Xfor will do.  The smaller Xfor had 105, 115 and 125 primary volt taps. Loads were taken of each set.

Thanks guys great information not sure I want to go into that much work plotting test results sounds interesting tough I'll keep your info W3RSW for future reference. Was wondering about the part number because I wasn't finding it any where in Stancor catalogs from the 30's to the 80's well that sucks. Guess I could just hook it up if it works it works if not oh well back to the drawing board.

Dave.