I am restoring a Philco 95 and the output xformer that couples the push-pull 45 tubes to the speaker has a shorted secondary winding. Can anyone recommend a replacement? Also, what is the recommended push-pull 45 plate load impedance and speaker impedance? Many thanks for your suggestions and help.

Ben: It's surprising that the ouput xfmr winding is shorted. They usually fail by opening up.

Your best replacement bet would be a Hammond universal P-P xfmr. See AES or RadioDaze: http://www.radiodaze.com/ Don't waste you money on the Hammond "Classic" series with ultralinear taps.

45's would do well with about 3-5K impedance on the primary, but with a universal xfmr, you can play around with several taps and see which ones you like. It's not all that critical, though.

You can guestimate the speaker impedance by measuring the resistance of the voice coil, and doubling it.

The primary load on the tube plates will be the speaker impedance multiplied by the square of the xfmr's turns ratio.
Doug

:I am restoring a Philco 95 and the output xformer that couples the push-pull 45 tubes to the speaker has a shorted secondary winding. Can anyone recommend a replacement? Also, what is the recommended push-pull 45 plate load impedance and speaker impedance? Many thanks for your suggestions and help.

Ben

I agree with Doug. Unlikely secondary of your output transformer is shorted. It may read only 1 ohm but that's ok.

http://www.nostalgiaair.org/PagesByModel/901/M0013901.pdf

Norm

:Ben: It's surprising that the ouput xfmr winding is shorted. They usually fail by opening up.
:
:Your best replacement bet would be a Hammond universal P-P xfmr. See AES or RadioDaze: http://www.radiodaze.com/ Don't waste you money on the Hammond "Classic" series with ultralinear taps.
:
:45's would do well with about 3-5K impedance on the primary, but with a universal xfmr, you can play around with several taps and see which ones you like. It's not all that critical, though.
:
:You can guestimate the speaker impedance by measuring the resistance of the voice coil, and doubling it.
:
:The primary load on the tube plates will be the speaker impedance multiplied by the square of the xfmr's turns ratio.
:Doug
:
:
::I am restoring a Philco 95 and the output xformer that couples the push-pull 45 tubes to the speaker has a shorted secondary winding. Can anyone recommend a replacement? Also, what is the recommended push-pull 45 plate load impedance and speaker impedance? Many thanks for your suggestions and help.

Actually, if you had a shorted secondary winding, you probably would something more sophisticated than a DMM, as the DC resistance reads about zero on a perfectly good one.

Lewis

Ben
I agree with Doug. Unlikely secondary of your output transformer is shorted. It may read only 1 ohm but that's ok.
:
:http://www.nostalgiaair.org/PagesByModel/901/M0013901.pdf
:
:Norm
:
::Ben: It's surprising that the ouput xfmr winding is shorted. They usually fail by opening up.
::
::Your best replacement bet would be a Hammond universal P-P xfmr. See AES or RadioDaze: http://www.radiodaze.com/ Don't waste you money on the Hammond "Classic" series with ultralinear taps.
::
::45's would do well with about 3-5K impedance on the primary, but with a universal xfmr, you can play around with several taps and see which ones you like. It's not all that critical, though.
::
::You can guestimate the speaker impedance by measuring the resistance of the voice coil, and doubling it.
::
::The primary load on the tube plates will be the speaker impedance multiplied by the square of the xfmr's turns ratio.
::Doug
::
::
:::I am restoring a Philco 95 and the output xformer that couples the push-pull 45 tubes to the speaker has a shorted secondary winding. Can anyone recommend a replacement? Also, what is the recommended push-pull 45 plate load impedance and speaker impedance? Many thanks for your suggestions and help.

:Actually, if you had a shorted secondary winding, you probably would something more sophisticated than a DMM, as the DC resistance reads about zero on a perfectly good one.
:
:Lewis
:
:
:
:Ben
:I agree with Doug. Unlikely secondary of your output transformer is shorted. It may read only 1 ohm but that's ok.
::
::http://www.nostalgiaair.org/PagesByModel/901/M0013901.pdf
::
::Norm
::
:::Ben: It's surprising that the ouput xfmr winding is shorted. They usually fail by opening up.
:::
:::Your best replacement bet would be a Hammond universal P-P xfmr. See AES or RadioDaze: http://www.radiodaze.com/ Don't waste you money on the Hammond "Classic" series with ultralinear taps.
:::
:::45's would do well with about 3-5K impedance on the primary, but with a universal xfmr, you can play around with several taps and see which ones you like. It's not all that critical, though.
:::
:::You can guestimate the speaker impedance by measuring the resistance of the voice coil, and doubling it.
:::
:::The primary load on the tube plates will be the speaker impedance multiplied by the square of the xfmr's turns ratio.
:::Doug
:::
:::
::::I am restoring a Philco 95 and the output xformer that couples the push-pull 45 tubes to the speaker has a shorted secondary winding. Can anyone recommend a replacement? Also, what is the recommended push-pull 45 plate load impedance and speaker impedance? Many thanks for your suggestions and help.

::Actually, if you had a shorted secondary winding, you probably would something more sophisticated than a DMM, as the DC resistance reads about zero on a perfectly good one.
::
::Lewis
::Many thanks to all for the info and suggestions. I will do additional checks regarding the shorted xformer. I was using a VTVM to measure the resistance and was not sure that a reading of 0 ohms is what the xformer resistance should be. Ben F.
::
::
::Ben
::I agree with Doug. Unlikely secondary of your output transformer is shorted. It may read only 1 ohm but that's ok.
:::
:::http://www.nostalgiaair.org/PagesByModel/901/M0013901.pdf
:::
:::Norm
:::
::::Ben: It's surprising that the ouput xfmr winding is shorted. They usually fail by opening up.
::::
::::Your best replacement bet would be a Hammond universal P-P xfmr. See AES or RadioDaze: http://www.radiodaze.com/ Don't waste you money on the Hammond "Classic" series with ultralinear taps.
::::
::::45's would do well with about 3-5K impedance on the primary, but with a universal xfmr, you can play around with several taps and see which ones you like. It's not all that critical, though.
::::
::::You can guestimate the speaker impedance by measuring the resistance of the voice coil, and doubling it.
::::
::::The primary load on the tube plates will be the speaker impedance multiplied by the square of the xfmr's turns ratio.
::::Doug
::::
::::
:::::I am restoring a Philco 95 and the output xformer that couples the push-pull 45 tubes to the speaker has a shorted secondary winding. Can anyone recommend a replacement? Also, what is the recommended push-pull 45 plate load impedance and speaker impedance? Many thanks for your suggestions and help.