Power XFMR Choice

[sherpa]

i'm looking at using Edcor's XPWR144 power xfmr for a simple se. my concern is the 3.5A limit on the 6.3 winding, will this be ok or should i try something different? the reason i'm going for the 144 is the 380/320 CT winding will give me options to drop the B+ rail for other tubes.

 

[neonthecat]

The SSE Assembly Manual states: "The main filament winding should be 6.3 VAC at at least 5 amps."

So, the Edcor XPWR144 may run too hot (or worse) when used at 5 amps.
The folks at Edcor are very helpful. Give the Technical Dept. a call for the definitive answer.

 

[Tubelab_com]

I specify a 5 amp winding to cover all possibilities with some margin. A SSE with KT88's will draw exactly 3.5 amps if all of the tubes are exactly at spec. An EL34 version will draw 3.3 Amps. The filament current could easily be +/- 10% or so. This could put the current close to 4 amps. A 4 amp winding would work, but 3.5 is rather close. See what Edcor says.

 

[Ian444]

I asked a similar question to Edcor recently, the answer was that their heater windings are designed to handle 10% more current than what they are rated for. So you can pull an extra 10% and after that you're on your own...