[mikeyg]

Finally found resistor 61. The resistance is a bit high but nothing crazy. Got 210 ohms instead of 145. The other two were really close within about 2 ohms of what the schematic read. Kind of excited to have this thing together. New output transformer should be here within a week. Hopefully I can ask intelligent questions I still feel out of my depth here

[RodB]

When you get ready to remove the old transformer don't unsolder the wires from the tube sockets. Just cut the wires within a half inch of the terminals leaving enough insulation so you can identify the correct pins when you attach the new wires. You can unsolder the old wire stubs then solder a new wire in it's place.

[Arran]

Quote Mr. Fix "Most Philcos of this era that have Push Pull output used the "screen grid resistor tap" method to get the inverted signal needed for the other tube in the Push Pull pair. Most of the 1941 sets used the '41 pentode, which is electrically the same as a 6K6. The B+ on these sets was only about 180V. I don't know why this was the case, because 250V is more common for tubes of this vintage."

I may have misspoke about what that chassis had for power output tubes, it was actually the Canadian version of a 40-180, so I can't actually remember whether it used #41s or whether it used 6K6Gs. It's in a box in a basement closet so I haven't looked at it in some time.
Regarding the low B+ voltages, most of this series of sets used an #84 or a 6X5 as a rectifier, which like #41s and 6K6s was popular for use in car radios of the period. I think the reason for the low B+ voltage was so they could power an 8 tube set using an #84 rectifier, at 250 volts the current output is only about 70 ma, run the tube at lower voltages and it can deliver more current without causing a heater to cathode short.
180 vdc was about what a vibrator supply could deliver in a car radio of the era, and since the set had push-pull 41s/6K6s the output was still a respectable 5-6 Watts, with lower distortion then a single ended 42/6F6. These sets were built to a price, hence why they used the "screen grid inversion" trick, less power then with a proper phase invertor tube, but it was one less tube they needed to use. It's strange that they did not incorporate a phase invertor tube into the 41-287 rather then wasting a socket on an extra double diode detector tube, it would be tempting to rewire the set to add one, then again maybe that would overtax the power supply?
Regards
Arran

[RodB]

Arran, I was thinking about the power supply capability yesterday when I looked up the 41 tube data. If there's 2 of them, they're using well over 100ma just resting, then add the rest of the tubes. I'd say it's a delicate balance. Then I saw a radio the other day that has 2 detector tubes, one for AVC and one for audio detection. Figure that?

[Arran]

Rob;
The specs I found give the plate current as 32 ma at 250 vdc, and the screen grid at 10 ma, at 100 vdc the plate is 9 ma, and the screen 3 ma, so the 180 vdc B+ volts for B+ was obviously chosen to get the maximum performance they could out of an #84/6X5 based power supply without blowing it up. https://frank.yueksel.org/sheets/155/6/6K6G.pdf This was from a Brimar tube manual which was a division of ITT over in Britain. Unfortunately it doesn't give a push pull rating.
Another trick Philco did was to use loctals with 150 ma heaters in them, the same as what they used in their AC/DC sets, that likely reduced the burden on their power supply as well, at least the heater winding. I must say that they did a good job, unlike the contemporary Brand Z models of that era most of the Philcos I encountered still have their original power transformers.
Regards
Arran

[RodB]

I have the RCA stats and the push-pull specs are for zero signal plate current at 250 plate volts to be 55ma, so at 200 volts it must be around 45ma. Screen current is 9ma at 250 volts and has to be 6 or so at 200 volts. If you keep adding options it gets real tricky to design these.

[mikeyg]

I have the new output transformer in and am wiring it up. I see where one lead from the old output transformer was connected to. This spot is where one wire that goes to the speaker connects. This is grounded to the chassis. There are two other wires to the speaker near that. They go across a resistor. It looks like the positive from my filter cap goes to one side of that resistor as well. Need help where to ground terminal c. Do I tie it to where the wire from the original output transformer was that is grounded to the chassis? And where to put my wire from terminal one from the output transformer. This is the p-t291 part that I ordered. I hope this makes sense and isn’t super vague it makes sense to me.

[RodB]

Check posts 12 and 32 for my instructions on installing the transformer. The schematic doesn't show a resistor across the transformer wires. You should be using 5 wires in the new transformer then assign each wire a terminal where the old one was. Match colors in the new transformer with the schematic old colors.

[mikeyg]

I have the blue and brown wires going to the 41 tubes across the cap like you posted. I have my red wire going the where the white and black wire was which is where my b+ voltage is. There was only 4 wires out of the old transformer. One is hooked to what I am assuming is ground since it has continuity to case. I still am unsure where terminal one should connect. The resistor looks like it is resistor 26 if that helps

[RodB]

Terminal one and C is the secondary winding, terminal C can be grounded and terminal one connects to the ungrounded speaker lead.

[mikeyg]

The only speaker lead that doesn’t show continuity to case is one that ties into the positive of my filter cap and my rectifier tube. Or at least that’s what I thought. I’m gonna go agead and assume I wired this up incorrect. I grabbed my other meter which an lcr. I clipped to a wire which does show continuity to case and I can hear a tone through my speaker. Is this where my terminal 1 should be hooked to? The other wire from my speaker goes to my 84 tube and connects to what I think is pin 2 which is also where that filter cap connects.

[RodB]

This is confusing. The speaker has 2 connections, which are the speaker voice coil connections. When you talk about the speaker connections those are the only two you should be referring to. Those two connections are to be connected to the secondary terminals C and 1 of the transformer. From your conversation and the schematic one of the connections is ground. The other three wires, red, blue and brown, I believe you have correctly wired to the tubes and B+. If you are still confused on how to connect it I'll need to see a photo. Did you take photos before removing the transformer?

[mikeyg]

I got it together. Works pretty good. Gotta do some better cleaning and some final small stuff before I put it back in the cabinet. Thanks everyone for the help.

[RodB]

I love it when you say that. Try different tone settings to see if there is distortion. Different volume settings at the low end will also change the tone setting.

[mikeyg]

I do have some shenanigans going on but I think it’s just a dirty volume pot. Have to tap on it at times to get the volume to stay steady. Need to fix my dial string and the lights are not all working. I need to buy some bulbs and replace some of the wires as they are falling apart. I think some deeper cleaning and better wire will work wonders for this thing. Going to take some time and re check all my resistors too. My meter was giving inconsistent readings half way through this because the battery was dying. All in all though I think all the hard work is done. Going to put my tubes on a tester and check those too to make sure they are all where they need to be