The PHILCO Phorum
which coil - model 52 - Printable Version

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RE: which coil - model 52 - Radioroslyn - 08-13-2016

SG voltage seem a bit low check #39,40, and 23. If #18 is too high it will cause the plate voltage on the 24 to be too high.

RE: which coil - model 52 - winston763 - 08-18-2016

I agree with the voltage differences but i can't seem to bring them down(on 24) /up (on 35).  

However, it seems to come back to the tickler coil i wound, as you stated.

For an experiment, I coiled a separate tube with more turns than i originally did on the tickler and connected the 2 open ends with alligator clips to the same points as the tickler.  In other words a supplemental "booster" coil.  Now i can align up and down the dial - i get 830 loud and strong along with the other stations for the first time. 

HOWEVER, the alignment is a very 'compressed' band on the dial with 830 located at 1100 or so and all the stations up to 1600. 

so, when i 'fixed' the actual tickler does this result point to too many "turns" as a result of this "booster" coil?  At least i know how to get the stations but ideally they'd like up better to the dial.
Sure appreciate your help !
Rich   

RE: which coil - model 52 - Radioroslyn - 08-19-2016

Hi Rich,
This what I can tell about the coil. If there isn't enough turns on the tickler the oscillator will run at the high end of the band but die out at the low end. I would try adding more turns to the original form. Don't know if you counted the old winding but would guess about 30T would get you close. Needs to be wound near the bottom of the form as the old one was. Wire gauge is not really critical but should be 32G or less. If it quits oscillating at the low end you'll need to add a couple more turns. You can also try baking the coil at lot temp to remove any moisture. Philco in some of their service bulletins from that time frame would mention lowering the value of the cathode resistor, this raises the gain on mixer tube making it a bit easier to oscillate.

By adding your extra coil this add a lot of variables in to the circuit. Placement is critical and using clip leads to connect adds capacitance and inductance to circuit. Both of these factors could be the reason for your tracking issues. Using a tetrode tube to do both the mixing and act as the oscillator is a bit of a stretch but was the technology was at the time. By adding a separate oscillator tube makes the circuit simpler but add to the cost, and this was at the peak of the depression.