[ccomer1955]

Yes, C13 ungrounded pin to the coil side of C14.
I'm not sure how to specify the part of the band switch, but it is the pin on the bandswitch where the lug on the coil 16 has a directly wired connection, so I'm getting zero ohms from Grid One of the 6A7 (pin five according to my tube manual) to that pin on the bandswitch. I was thinking that would show me resistance across one of the windings on coil 16 because that is what the schematic seemed to show because I'm seeing a connection from the start of the first winding of 16 to tuning gang trimmer C11 and grid 1 of the 6A7 (pin 5). So I was attempting to get the beginning of the first winding to the end of it. The end of the first winding seems to be the beginning of the second (or the same pin, so I measured from that pin on the bandswitch to the ungrounded side of C13, then from the ungrounded side of C13 to the coil side of C14.
What I'm trying to do is get a sense of the health of coil 16 by measuring the resistances across its three windings. Where should I be measuring? I can, pull the coil, I suppose.

[ccomer1955]

I have one other concern for now (besides potentially rewinding the osc. coil): on the bandswitch, one of the pairs of contacts NEXT to the pair where the antenna lead and R3 are has C12 going to ground, but it also has a wire connecting the contact on the bandswitch to the ungrounded side of C13. Is that correct? It has been in the set since I got it, and I've never touched it, but I don't see it on the schematic except as a dotted line. Dotted lines denote some switched connections?

[morzh]

According to the sch it is not correct, but if it loos like factory soldering check out the changes document first before correcting it.

[ccomer1955]

It does, and will do. I have noticed what I think might be a problem with the tuning gang trimmers. Here are photos of both trimmers (C7 & 11). Unfortunately, the one of C7 is a bit blurred because it was difficult to get the focus in such close quarters, but it looks to me like the bottom plate of the trimmer on C7 is broken off on the near side. I've included the photo of C11 for comparison.
    This one is C7.
The one below is C11.

In addition to the fact that they are filthy, dirty, C7 looks broken to me. Would this be a reason for no oscillation?

[Mondial]

The only thing about the tuning cap which would cause no oscillation would be a short across the plates. If the mica is missing or damaged between the trimmer plates it could cause a short.

Best way to check would be to remove the wires from the tuning cap and check for resistance between the rotor and stator plates. Rotate the cap shaft over its full range. You should have an infinite resistance (open circuit) reading. If you read a short or low resistance then there is a problem.

[ccomer1955]

Thanks, that gives me a method. Assuming the caps and resistors on the 6A7 circuit are in spec. and wired correctly, that would leave me with the osc. coil or the tube as reasons for no oscillation, right? Or possibly a dirty bandswitch? If I measure across each of the three windings on the coil (16), does anyone know what sort of resistance numbers I should be seeing. Two of the windings are quite short (I think one has 7-8 turns). What I'm seeing is zero ohms (just continuity...maybe .1 ohms), 3.4 ohms, and 72 ohms (in no particular order) measured at the lugs of the o/c. coil. However, I've read that even given correct resistance, the coil can...what is the word...leak?
Also, if I push a modulated signal at 1500 at the antenna and can hear it when I tune the dial to that part of the radio's dial, I'm most likely hearing the signal generator oscillating? Is that true? I can do that, but the sound coming from the speaker is low volume.

[ccomer1955]

The only service bulletin I can find for the Philco 66 is #197. It says nothing about a lead connecting the part of the band switch to C13 that I can find. It is odd to me that this directly wired connection to C13 is operative in broadcast mode but out of the circuit in SW. It is on the same part of the band switch that C12 connects to (but C13 goes to ground). Does anyone know if there is a service bulletin in addition to 197?

[ccomer1955]

I'm happy to report my old nemesis, the Philco 66, started playing radio signals at 10:30 PM CST. I had pulled the o/c. coil again to check resistance at the lugs and out of circuit, the long coil ohmed at 3.4, the small one in the middle ohmed at .8 ohms, and the larger wire short one at the bottom ohmed at 0 ohms. That sounded sort of reasonable to me and I can't see any of the dreaded green patches everyone talks about. I started cleaning it up so I could see the connections of the coils to the lugs better, and I decided to see what would happen if I removed the 70 ohm resistor across two of the lugs the service notes say should be in series with C14. I replaced it with a short piece of 22 gauge hookup wire. Just to see what would happen, I put the coil back in, replaced all the connections taking care to make good physical contact and strong soldering. Took a breath, plugged it in, turned it on, and got a buzzing noise at the high end of the scale. I turned the tuning cap to the middle and got static, turned it to the low end, and got a preacher telling me to read the Bible. I wound out the 10' antenna I had on it, put on a ground, and the dial cleared up significantly.
I still get buzzing between stations that disappears when tuned to a station and the volume at full is not that loud--but loud enough to fill the small room where my bench is, but the radio tunes across the dial, now. The buzzing is worse at the high end of the scale. I will take more complete voltage readings tomorrow, but the 6A7 grid cap puzzles me: it read at about .6 v positive voltage.
Thank you, Mike. Enjoy what's left of your vacation. Thanks to Mondial and Ron and Warren as well. My to do list is 1) Align this set as soon as possible, 2) find what voltage gremlins I have left, 3) clean up some more, 4) experiment with tube options for the best sound.
I still don't trust my signal generator, but I was able to get channel B to produce zero beat at 1200 and at 580 to day and repeat the operation, so I guess at least channel B is usable.
Advice on how to proceed, anyone.

[ccomer1955]

Back in the cabinet where it sounds better. The phone camera made it look lighter and orange, though. This one represents several firsts for me: first filter circuit rebuild (not just replacing electrolytics, first cathedral, first major veneer replacement (on the front where I'm sure folks can see, but I'm happy with it).
It's playing "Ring of Fire" which I think is appropriate. It might be a daily driver for a while.