Phase splitting transformer design
 

Hi!

How should be winded a good Phase splitting transformer?
1. Bifilar mode, but with a center tap? (Like e.g. EDCOR's XSM10K:10K) Some people says its works, but some says it is not good.
2. In a "classical" sectioning way, like e.g. 3 section of prim. and 2 section of sec.

Greets:
Tyimo

i have a suspicion that having several vertical sections with bifillar winding will even be better....dual section bobbins are available, but they can be made into 4 vertical sections.....

In my experience you are right Tony. A while back I was thinking of winding some output transformers using the Pi winding technique. To prove the idea I wound a center tapped anode choke for the 7N7 drivers in my 807ish amp (5B-255M). I used a pretty small C core transformer that came from a current injection rig. The first wind was a dismal failure, I just used normal interleaving. The max frequency was poor due to interwinding capacitance. The second try was split bobbin in two halves also using normal interleaving, this was better but I wanted more. The last try used a bobbin split into six vertical sections, each section had five layers. This choke was nearly perfect and I was quite pleased with it. As a phase splitting tranny it also works very well. The only trouble was I didn't write anything down or take any photos during the wind up. Doh. So I only have one and the likelyhood of making another one the same is slim. I will have a rummage in the junk box and take a photo of it if anyone is interested. Another good thing about this winding method is that although it takes a bit of time to make the bobbin the sections are narrow and there is no need for neatly wound layers.

Cheers Matt.

Hi Tony!
How do you mean this bifilar winding with the Pi winding technique?
Connecting the primaries in series and the sec. in parallel?
Do you recommend the Pi - bifilar winding as a good counter to the capacity problems of the bifilar winding technique?

Greets:
Tyimo

Hi Matt!
Yes, I am interested!:)

Greets:
Tyimo

two ways to do it, first is bifillar in 4 vertical or pi sections, second is 4vertical sections with primaries and secondaries in juxtaposition with each other....the first will be easier to do since you wind both primaries and secondaries at the same time...

O.K. Thanks!
How to split the bobbin into 4 vertical section? What is the best way?
I have only normal bobbin or a simple split bobbin ( 2 section)
Is there any trick?
Tyimo

yes, the 2 section bobbin can be converted to 4 section by using spacers that can be removed for winding, make sure to put in a permanent spacer made from thick plastic formed to fit...

I can tell from first hand experience that Edcor XSM15k:15k does NOT work well as a phase splitter. They measure fine with one end of the secondary grounded but but the frequency response is completely devastated if the CT is grounded instead.

Thanks Tony! I will try it.
greets:
Tyimo