transformer in the u*67

[omeiko]

Does anyone have any info about the tx used in the u*67? Is the feedback winding just a half of the dual secondaries or something more advanced?

I'm kind of wishing that I could perfboard the circuit with an oep or a lundahl laying around... Well of course I could do it anyway but I doubt it would work correctly?

Thanks,

Okko

 

[rafafredd]

Contact HAUFE and ask for a BV12. I´m sure they can still sell you a original one!

If it´s not HAUFE, than contact PIKATRON and ask about a BV12.

 

[Lukpio]

Hello,

a picture says more than a thousand words...

Best regards

 

[omeiko]

Thanks.

If I read the picture correctly the tertiary windings has 1/3 of the turns of the main secondary windings.
So no oep-tx for this one.

It would be fun to try how a correct circuit around a chinese kk*67 copy would improve the sound of the capsule.

thanks,

Okko

 

[CJ]

What kind of tube in there?
Maybe go for triode wiring and load the cathode to cut down on transformer products?

Ask Gus.

 

[Lukpio]

Hello,

All windings of the transformer in the U67 are connected in series for 200ohm operation, so turns are as follows:
primary: 2x2700= 5400 turns
secondary (feedback): 2x125= 250 turns
secondary (output): 2x390= 780 turns

hence the primary to feedback has 21.6:1 ratio and the primary to output about 6.9:1 ratio.

The tube is a triode-connected EF86.

Best regards