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Selecting a pwr xfmr?

3/29/2000 12:31 AM
Wild Bill
Selecting a pwr xfmr?
I don't think this has been asked in the year or so I've been checking the bbs - how do I compare the current draw in an AB-class amp to the rating on the pwr xfmr?  
Fer instance, I've got a Hammond 279X rated 425-0-425, at 150 ma. Now that's continuous and if it was a ham transmitter I would add 50% for intermittent duty (ICAS). I'd add 50% if it was a choke input filter. But how many EL-34's can I supply?  
There's more than enough for the idle currents but if I were to run 4 EL-34's the peak currents can total 400 ma ! Some of that is the filter caps job I know but just how far can I push that continuous current rating? Is there a true formula or even a reasonable "guesstimate" percentage?  
---Wild Bill

Bruce I'd say your still stuck with a pow... -- 3/29/2000 3:32 AM