I am trying to find a replacement for the Audio output transformer for my Zenith 10S464, chassis 1005. Half of the center tap primary is open. The 10" speaker (49-379) is OK and measures 2 ohms DC, I think what would be around 4 ohms actual imped. and the field coil is ok. The Zenith part number on the audio xformer is 206AG379. The schematic shows a primary DC resistance of 550 ohms with 2 6V6's in a push-pull output. Any ideas for a replacement would be greatly appreciated. Wayne

Just about any universal CT xfmr for push-pull will work fine, such as Hammond 125J (available from RadioDaze or AES). You can play around with the taps to see which sounds the best to your. The ratios aren't all the critical.
Doug

:Just about any universal CT xfmr for push-pull will work fine, such as Hammond 125J (available from RadioDaze or AES). You can play around with the taps to see which sounds the best to your. The ratios aren't all the critical. Doug Make sure you check the frequency response specs in the catalog. The cheapest only goes to 150 hz. This will drastically impact your bass response. They have a better one that goes too 100 hz, and a really good one that goes down to 30 hz. Just for the record, your primary impedance should be 4-5k ohm per plate. and your speaker is probably closer to three ohms. Generally the inpedance is 25% higher than the DC resistance. An 8-10 watt rating is good.

Thanks for the help on the audio transformer. I ordered the Hammond HX125J from Radiodase plus all the replacement caps. I also had to replace the power xformer with one from another matching chassis. My 10S464 aparently got fried 60+ years ago and has been stored in a barn. I have the Vol 1&2 Zenith service manual but that's not much help with transformers. Has there ever been a cross reference published for Zenith Xformers? Thanks again fellows. Wayne Lewallen KQ4J

Those Zenith sets with dual 6X5 rectifiers sometimes had their power xfmr smoked due to an H-K (heater - cathode) short in a 6X5. Zenith had to make good on waranty repairs, which included replacing the xfmr and rewiring the rectifier section to use a single 5-V rectifier tube.

Inspect your set carefully to see how it is set up in the power supply area and whether it has been modified. If it's still set up to use dual 6X5s, it would be a good idea to replace the 6X5s with two NOS 6X5s, preferably ones that have the X-shaped plate configuration. You should also fuse the power xfmr primary and maybe even the center-tap of the high-voltage secondary winding.

If you will be using dual 6X5s, I would install a CL-90 current limiter in the xfmr primary ckt. This will cut down on turn-on surge, and reduce wear and tear on the rectifier tubes.
Doug

you can probably find a power transformer here:

http://www.oldradioparts.com/pg2a23e.htm

Thanks for the Old Radio Parts direction. I have found a power working xformer from another old radio.
Oldradioparts had the same xformer in stock for about $17.00 used. That is a great price considering a new Hammond replacement is around $120.00.

:you can probably find a power transformer here:
:
:http://www.oldradioparts.com/pg2a23e.htm

I found a 10S531 (1OA1 chassis) cheap with a good xformer. The power supply is a little different than my 10S464 in that the 6X5 cathode and heaters are tied together on each 6X5 in the 10S531. The power xformer has a seperate winding for the 6X5 filaments, in addition to a secondary 6.3V winding for the remaining tubes. I have a CL-90. I will install it in one leg of the 110V primary. After seeing the damage to this radio I'm definately fusing the 110 AC and the HV secondary. Any suggestions on fuse values would be appreciated.
Thanks again, Wayne

:Those Zenith sets with dual 6X5 rectifiers sometimes had their power xfmr smoked due to an H-K (heater - cathode) short in a 6X5. Zenith had to make good on waranty repairs, which included replacing the xfmr and rewiring the rectifier section to use a single 5-V rectifier tube.
:
:Inspect your set carefully to see how it is set up in the power supply area and whether it has been modified. If it's still set up to use dual 6X5s, it would be a good idea to replace the 6X5s with two NOS 6X5s, preferably ones that have the X-shaped plate configuration. You should also fuse the power xfmr primary and maybe even the center-tap of the high-voltage secondary winding. Thanks again, Wayne
:
:If you will be using dual 6X5s, I would install a CL-90 current limiter in the xfmr primary ckt. This will cut down on turn-on surge, and reduce wear and tear on the rectifier tubes.
:Doug