Use P-P OPT for SE?

[807tubenut]

Say I had a p-p transformer with the right primary resistance for a SE amp, could I just not connect the center tap, and be in the ball park?

[TheGimp]

No, the dc current will saturate the core and it won't work.

Use the search feature and you will find a lot of discussions about how to get around this.

SE cores are made with a gap in the flux path to prevent core saturation.

[Frank Berry]

You could possibly use the transformer if you load the other side of the primary with a resistor to B+. Adjust the value of the resistor so that it draws the same current as your output tube.

[Yvesm]

Originally Posted by Frank Berry

You could possibly use the transformer if you load the other side of the primary with a resistor to B+. Adjust the value of the resistor so that it draws the same current as your output tube.

And half the power will be wasted into
A CCS built around a pentode does a better job.

Yves.

[rock4016]

Another option would be to use a parafeed choke and dc blocking cap.

Different Kinds of Output Configurations

[Yvesm]

Originally Posted by rock4016

Another option would be to use a parafeed choke and dc blocking cap.

Different Kinds of Output Configurations

True !
But you move the problem of the core saturation by DC to the choke that must be gapped and thus huge to maintain sufficient primary inductance for not shunting lowest frequencies.
However, you may choose the value of the blocking cap such that the hi pass filter it forms with the primary of the OPT be somewhat resonant just above the lo cut !

Yves.

[807tubenut]

Hmm, I wonder if I can re-stack the plates, and use some PTFE tape to gap the I's from the E's, what do you think guys?

[Yvesm]

Originally Posted by 807tubenut

Hmm, I wonder if I can re-stack the plates, and use some PTFE tape to gap the I's from the E's, what do you think guys?

Better than nothing but you'll still reduce drastically the primary inductance.
Start with a thin gap: a single bit of printer paper is about 0.05 mm thick giving an effective gap of 0.1 mm because the magnetic flux crosses it twice: Once at the center tonge and once at each leg.
(I just realize how curious it is to describe the E as having its tongue between its legs )
What is the size of your plates/lams ?
Roughly a SE OPT is twice the volume of a PP for the same output power and comparable lo frequency cut off.

Yves.

[807tubenut]

E plate is .935" for the center across, 3.010" LOA down the back of the E plate, 2.515" Long from the open end of the E to it's back. each plate is .020" thick


All the plates as it sits, are .955" thick over all.

[Yvesm]

If I understand correctly, the lenght of the I plate is 3" ?