The AM Forum

When a transformer is stamped 2.5kv-0v-2.5kv what does that actually mean?  Can one expect in the neighborhood of 2.5kvdc out or 5.0kvdc out?  Transformer numbers always confuse me.  I guess that will depend on the type of rectification used.

Bob,
That means 5000 volts center tapped. The numbers you see means it should be connected to a full wave rectifier to get 2.5 Kv out. A bit less with a choke input filter X.9. A cap input filter will give you about 3 KV. Mignt not be wise to put a bridge on it for 5 KV since the insulation may not handle it.  a grounded CT each end will swing  minus 2500 to plus 2500. Float the CT and hang a bridge off it and each end swings 0 to 5000 volts since the other side of the bridge clamps the opposit end to ground. Then the CT swings 0 to 2500 volts. Sometimes you can get away with it sometimes you can't. It depends on the insulating rating.

OK, thanks for the refresher.  I got confused when I was seeing 5Kv when the device was telling me it was 2.5kv.  I bought the thing year ago and couldn't remember what I was getting.   Looks like I'm good to go then.  Thanks.

Sounds like something interesting is in the works. :D

Working on a plate supply for the 813 rig.  Trying to decide what tranny to use.

I'm glad to see I wasn't the only one that questioned this concept. The one I have problems with is filament transformers. A for instance: I want to build a HB-833 X 810's. I need two 10V 10A filament transformers. Do I get a 10VCT ie. 10vac-0-10vac (and is that called a 10V fil. tran) or do I get one that is 5vac-0-5vac? I think I know the answer but need a confidence booster.

Bob, I have a 7600v, 350lb pole pig if you need more iron than that. :P

Mike,
A 5-0-5 is a 10 V CT transformer. The CT is where cathode current is applied and G3 in the case of the 813. This balanced approach cancels the AC component on the fil.so you don't get hum. You can use a pair of diodes or resistors to create a CT if your transformer does not have one.

Cool!

the best way to be sure is to fire it off with a meter hooked to it! I usually put my 260 on the 5000vac scale and clip the leads to one leg and the CT and see what you get. It could be either way. The meter will let you know for sure.
                                                      the Slab Bacon

Frank said:
Thanks Frank. I kind of thought that was the proverbial way to go but I always seem to lose it in the 'grey matter' ;)

Hey Jared, I think I'm OK Fine.  I have a ball buster of a transformer (about 100lbs) I 'm going to use. The outpoot is just right.  I was testing others that I've collected and this monster will fit the bill despite its physical size and weight.  One things for certain my rack won't tip over.