[Ron Ramirez]

Okay, here's an update.

8:00 am.

I tested all of the tubes. The 6A8G had an H-K short and was tossed. Luckily I had another, good 6A8G and it went into the 6-S-128.

I also replaced the 5Y3GT with a 5Y3G even though the 5Y3GT tested good. The 5Y3G is more "period correct" for this set.

I had decided last night that I should test the wave trap and the odd little coil (labeled "Antenna Choke" on the schematic). It is a good thing I did.

The wave trap was OK. But the antenna choke was open.

   

I thought I found a break at the beginning of the winding where it soldered to the terminal. I removed one turn and resoldered. Checked again, still open!  

Hmmm...what could I do to try out the radio until I either rewind or replace this antenna choke?

Philco to the rescue!

Then I remembered a little 2.5 mH RF choke that had been on my workbench since I converted my Philco 70 to AVC.

   

Yes, it measured 95 ohms on my DMM.

So, in it went:

   

Finally, it was time. I removed the speaker from the cabinet, attached my longwire to the antenna terminal, and plugged the Zenith into my Variac.

I slowly brought up the voltage and...

NOTHING.

I touched the grid cap of the 6F5G and...NOTHING.

Then I noticed the screen grid of the 6F6G glowing bright red.

A tell-tale sign...bad audio output transformer!

I shut everything down, unplugged the speaker, and checked the field coil and the output transformer primary.

The field measured around 1800 ohms. I noted the schematic calls for 1000 ohms. I'm hoping that maybe I made a mistake and the field is OK.

Anyway...I measured output transformer primary, and...OPEN.

I couldn't help but say it out loud (only I said it in English)...

Черт побери!

A mild expletive. Google it if you're so inclined.

This radio has had one issue after another, and I'm tired of messing with it for now. Time to set it aside for awhile. The speaker is back in the cabinet, the 6-S-254 chassis is back in the garage, and the 6-S-128 chassis is still sitting on the bench.