The PHILCO Phorum

The PHILCO Phorum > Philco Radio Discussions > Philco Electronic Restoration > Philco 650 K-17 Speaker Transformer
Full Version: Philco 650 K-17 Speaker Transformer
You're currently viewing a stripped down version of our content. View the full version with proper formatting.

wardmc1

11-20-2018, 01:23 PM
Hello Everyone,
I am having issues with a K-17 speaker. The output transformer was bad and I need to replace it. I'm having trouble crossing the 32-7078 transformer. I bought a Hammonds 125D universal push-pull, but and not sure how to wire it up. Anybody have experience with this and can point me in the right direction?

Thank You in advance.

Matt

morzh

11-20-2018, 02:25 PM
You have 10,000 kOhm to 1.11 Ohm transformer, which means you have the ratio of 95 of I:II windings. The impedance at 1.5 ohms should be 13,636 so the closest you get is by connecting your speaker between 3 and 4 of the secondary.

Radioroslyn

11-20-2018, 07:41 PM
Hmmmm
The push/pull triode connected 42's w/fixed bias p to p load is 6K sez my '40 RCA tube manual and spec on the original transformer is 5.9K. With that in mind I would go w/ 1 and 3. Rca sez it will make abt 10watts @ 2% distortion. Wired as penodes they will abt twice the audio power but almost triple the distortion.
YMMV

morzh

11-20-2018, 09:46 PM
I think you are right. I didn't look much at the output stage, it seems to be direct-biased triode connection (cathode biased triode is still 10K) which is 6K.

Radioroslyn

11-21-2018, 11:47 AM
>I think you are right.
I try!
The PHILCO Phorum > Philco Radio Discussions > Philco Electronic Restoration > Philco 650 K-17 Speaker Transformer