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Philco 84B Power Transformer
#31

There are two windings on the oscillator coil, usually it is the outer winding that is open.

Steve

M R Radios   C M Tubes
#32

Over the next couple of days, I'll pull it, count turns and prepare to rewind the same directions and number of turns. If it is likely the outer winding, can I carefully remove the outer only and keep the inner? Or should I do both out of precaution? Thanks and have a nice feast tomorrow guys-
BDI
#33

Check both windings for continuity before rewinding, no need to rewind if it is not open.

Steve

M R Radios   C M Tubes
#34

I just pulled the osc coil. It visually looks great...no green and no visible breaks. The outer winding has continuity=2.5Ohms, Inner cont=3.5Ohms. Seems good to me, but I'm no pro. I will reinstall with new wire and repeat the squeal test, in case wiring or connection was the issue.
#35

Those value sound good.
There is a lot of good info on philco radios here. http://www.philcorepairbench.com/tips/svctip44.htm and here http://www.philcoradio.com/tech/index.htm
#36

I put the osc coil back in and repeated the squeal test with second radio. Although I didn't hear any squealing, I did notice that there was a small range about halfway up the dial where the buzzing in the second radio cut out to complete silence when the 84 was being tuned. Is this proof of my osc working? Also, when I touched the third trimmer adjustment screw with a driver, the buzzing in the second radio cut out as well. I rechecked my antenna coils and it appears that one is possibly open. Last time I checked, both coils seemed OK. Now I get 0.00 Ohms for one coil and 3.5 Ohms for the second antenna coil. I guess this is where my problem lies. I am getting only buzzing across the dial which changes intensity. Also, rechecked all voltages - all are good.
#37

If the volume control is turned all the way down it would read 0.

the osc sounds like it might be working.
#38

Yes, it sounds like your oscillator is working. The quiet spot in the reception of the second radio occurs when the strong carrier signal from the 84's osc is being received and masks the background noise.
#39

I just pulled the antenna coil. Looked great like the osc coil. Rechecked the continuities; both were good - Vinzer, I think you are right. I must have had the volume down. It's back in now and only varying buzzing across the dial. Not sure what to try next. Would an alignment using a signal generator be the next step at this phase? I don't have one but I may need to get one. I'm still confused why the radio worked for over 2 hours yesterday, then shifted to just buzzing, after playing good on one channel, but had also picked up 4 faint channels. Something changed - strange. If you guys have any suggestions I'd really appreciate your help. Thanks-
bdi
#40

Do other radios in the same room pick stations ok could some kind of interference have you adjusted the regen control on the back you might try turning it some to see if that helps
I think it's the right control on the back
#41

I tried adjusting the third adjustment which increases/decreases the volume of the buzzing but no channels. Other radios work fine. I did notice the other day (before it stopped working) that the channels that worked had a very narrow range, making it almost impossible to tune to a channel. I also noticed that the volume adjuster only worked from the halfway point up and no low volumes were possible. Maybe an alignment is in order...I don't know what to do. I will try to buy a signal generator and do some more troubleshooting.
#42

Do you have all the tube shields on?
#43

there is only one shield and it has been on. are there any other voltages that I can check?
#44

Other than alignment I am out of ideas maybe some one else will respond.
#45

Have you considered the fact that 84 is a regen-superhet and as any regen has very sharp tuning?




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