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Interstage transformer for single ended use

Posted: one year ago Quote #1004
If I understand correctly, the WSM and XSM series are designed for push-pull use. I and many others are looking for an interstage transformer for single end use, which needs an air gap to handle DC. Transfomers like this are available in the EU and Asia, but I'm in the US and would like to see an Amerecan made option.

Since the WSM and XSM are made to order, can I get them with air gap to handle DC?
Posted: one year ago Quote #1005
By butt stacking (air gap) it changes the performance of the transformer. They would need to be designed for single ended use. What type of AC current, DC current and voltages are you thinking about?
Brian Weston
Tech Support
EDCOR Electronics Corporation
Posted: one year ago Quote #1006
"What type of AC current, DC current and voltages are you thinking about?"

Brian:

I have a modest collection of preWWII tubes - 26, 27, 45, 46, etc. I'm experimenting with transformer coupling.

I have two applications of interest:

1. Single end 27 or 46 transformer coupled to drive 45 or 2A3. It's been suggested to me to try 1:1 or 1:2,  15-30 mA. DC voltage 250; line level input.

2. Output transfomer for low gain preamp. I'm thinking 5k:300/ 15mA or 10k:300/10mA. Might you have a product like this already?

Thank you!  
Posted: one year ago Quote #1007
I will look into it. We do not have any matching/coupling transformers that are designed for any DC current.
Brian Weston
Tech Support
EDCOR Electronics Corporation
Posted: one year ago Quote #1008
Brian:

I am sure you willl have demand for an interstage transformer air gapped for DC. If the popularity of your X series single ended output transformers is any indication, a similar interstage will be very popular.

Look forward to what you cook up.

Best, Dale.
Posted: one year ago Quote #1026
Hi...Take a look at some respected 300B designs and see what they are pushing through their drivers, then add a little to account for the loses through the IT. This should tell you whether 20mA of drive will be enough. I have a hunch you might struggle. If I was doing it I would build the Karna instead.
Another option would be to consider direct coupling, with possibly an interstage transformer between an initial preamp and a driver.
Posted: one year ago Quote #1027
Thanks for your suggestions. I've been thinking about the Karna amp too.