[davemc]

I am working on a Philco 60 cathedral. The seller had marked it "late" version. Serial number is G65194. The schematic differs from Riders and the Philco service information I have. Unlike Riders, it has 4 IF trimmers, and a fixed capacitor rather than a police band adjustable padder. The mica capacitor shunts the broadcast padder when switched to Police band. It is good, measures 1320pf but has color dots red/brown/red? The radio works great on broadcast band. It has been recapped, all resistors and tubes checked, etc. But there is NO reception on Police band.

The bandswitch shorts out a portion of the antenna and oscillator coils on the Police band. It is working. The antenna coil secondary measure 6.8 ohms on BC and 2.1 ohms on Police. The oscillator coil measures 2.7 ohms on BC and 1.4 on Police. On Police, a fixed capacitor is also shunted across the BC padder.

With that capacitor in place, I get NO reception on Police. I tried substitution and other values - no luck. If the shunt padder is removed, I get some reception. With the dial at 1500, it receives 1500. Dial at 1600, receives 1560. Dial at 1700, receives 1600. Dial at 1800, receives 1675. No reception past 1850 - even with the signal generator cranking out maximum voltage. So it is obviously NOT tracking properly. There are no police band alignment adjustments that I can find.

The radio has seen some "servicing" in the past, so I'm no sure what is original and what is not.

Does anyone have any ideas on what to try next? Do any of you have a working version of this set (with the variations mentioned above)? I'd really be interested in finding out the correct value of the police band fixed padder.

Thanks

[exray]

Not a whole lot can go wrong here. Make sure the bandswitch contacts for the coils are both doing their job in shorting out a section of the coil.
On the mica cap Philco uses their own color code. Details can be found on Chuck's site.

GL,
Bill

[Ron Ramirez]

Read this page on my website - it should give you some help, as it documents all of the changes made to Model 60 over the years.

http://www.philcoradio.com/tech/60evol.htm

[davemc]

Thanks, Ron. My set is run 11 with the 1936 cabinet. And the Police band padder, part #11 (1400pf) actually measures 1320pf (using a DVM capacitance meter, which is not all that accurate) and no leakage. The band switch has been cleaned and is indeed shorting out turns on both the antenna and oscillator coil on the police band.

And again, the radio works well on the broadcast band.

Today I plan to double check the wiring, since I had to remove BOTH the antenna and oscillator coils in order to rewind the short wave primary (antenna coil) and feedback winding (oscillator coil). Both were open, as are almost every Philco I have restored that used a winding on top of plastic insulation. The tuned windings were not disturbed in both cases.

I also plan on determining the frequency the oscillator is actually running at a couple of points on the dial using a counter or my Realistic DX440 radio, whichever works.

I also plan on trying to grid dip the antenna coil to see where it is resonating on the police band. This may or may not work with the coil inside its shield.

Thanks!

[Chuck Schwark]

Also be sure to change any resistors in that set that are outside +/-20% nominal values.
I'll bet you'll find a few. With upward drift, any resistors in the mixer/osc stage that have changed may effect operation.
Check all coils for continuity of all sections, if have not already.

Chuck

[davemc]

All coils check out OK. All resistors are now within 20%, and most within 15%. I had to change out quite a few. The 6A7 is NOS and checks very high. B+ is on the money at 257 volts (at 110 volts in). The screen voltage on the 6A7 and 78 is a little low at 67 volts. But it's hard to say what it should be with all the changes. I did not disturb or check capacitor 13 (110pf mica).

The set is NOT OSCILLATING on the Police band. The oscillator grid is positive and I cannot pick up anything on my Realistic DX440. When the oscillator feedback coil (which was of course open) was rewound, I used about 15 turns. I am not exactly sure how many turns were on the original, since it was in many pieces (green disease). But I assumed it was not critical (that was the case with several other Philcos I have restored and had to rewind this coil). In any case, I pulled the coil out and rewound the feedback coil with 22 turns (#38 cotton covered wire). Still no oscillation, although I get squeals and what sounds like parasitic oscillation at the high end of the band.

Is it possible I should have used FEWER TURNS on the oscillator coil feedback winding? There was no change in performance on the broadcast band.

Has anyone restored one of these recently and remember exactly how many turns were used?

I used scotch tape to replace the original plastic insulator on which the coil was wound.

The winding was positioned approximately where it was originally, on the cold end of the coil. And the winding direction much be correct, else the broadcast band would not work.

THANK!!!

[davemc]

Update. I removed the oscillator coil and reduced the feedback winding to 10 turns (so now I have tried 10, 15, and 22 turns). I also checked capacitor 13: it shows no leakage and measures 110pf, right on the money. I checked all the resistors again. 14 (32K) measures 37.16K. 10 (51K) measures 53K. 9 (300 ohms) measures 394 ohms (I paralleled some resistance to get it to 300 ohms - no difference). Although the B+ is correct and resistors 19 and 24 are close, the converter screen only measures about 55 volts (Riders schematic says 85 volts to cathode).

IF I DISCONNECT FIXED PADDER 11 the set will oscillate over about half the dial (lower half). But of course with no padder, it is about 600KC too high. Putting ANY value of padder in place kills the oscillation.

This is certainly the most difficult restoration I have ever attempted - and such a simple radio!

It has to be the oscillator coil, but it works perfectly on the broadcast band, and only the MIDDLE part is shorted out on Police (plus the fixed padder 11 is added). Maybe the number of turns on the feedback winding is critical in this case.

Getting ready to punt ....

[exray]

The 89 coils are well known for moisture absorption so its not a far reach that your 60 coil might have excessive leakage. Check for DC resistance between non-connected terminals and the mounting lug to chassis (if there is one). My 'bad' 89 coil had dc leakage as low as several hundred K-ohms on a DMM.

If you get any resistance at all (save something like 30Megohms) it might pay to bake the moisture out of the coil form and reseal it.

GL,
Bill

[Ron Ramirez]

Did you wind that outer winding of the oscillator coil clockwise, or counterclockwise in relation to the coil connections?

The outer winding must be made counterclockwise. The oscillator will not work properly if the outer winding is made clockwise.

I do not remember the correct number of turns at present; that information is downstairs, I am upstairs, it is bedtime and I'm not going to look tonight.

You should use 38 gauge wire on that outer winding.

[davemc]

Well Ron, you nailed it! I guess that's why they call you Mr. Philco! I temporarily swapped the leads/components on the feedback coil terminals. Broadcast band worked as before, but short wave/police sprang to life!

I was prepared to rewind the coil if backward, but was fooled into thinking it was correct since the broadcast band worked fine even with the tickler/feedback winding backward. Just guessing, I suppose the 110pf capacitor between the bottom of the tuned winding and the feedback winding provided enough feedback on the broadcast band for the oscillator to work (and work well: -12.5 volts on the oscillator grid measured to ground). Could it be that the feedback winding is only there for the short wave band? I'm not exactly sure how the circuit works.

Anyway, if you can let me know the number of turns that are supposed to be on the coil, I'll rewind it. It now has 10 turns, and everything works fine.

Thanks again

[exray]

Well Ron, you nailed it! I guess that's why they call you Mr. Philco! I temporarily swapped the leads/components on the feedback coil terminals. Broadcast band worked as before, but short wave/police sprang to life!

I was prepared to rewind the coil if backward,

but was fooled into thinking it was correct

Amazing , huh?

-ex

[Danny]

I've been beating my head with a Philco 60 for the past few days. No reception at all on either band. Can anyone give me a few pointers on how to demystify this antenna coil? Looking at the bottom of the coil with the ground lug at the 6 o'clock position going clock wise can you tell me which connections are paired and resistance I should see between the two? Also a connection at the top end of the coil. Thanks for your help.

[davemc]

Ron's site gives the resistances of the various windings. On my radio, here's what I measured:

With the ground lug as lug #1 and going clockwise:
Lug 2: AVC (bottom of secondary) to bakelite block cap 7 and R21
Lugs 3-4: to bandswitch (shorted out on shortwave) - Center of secondary 4.9 ohms (5.5 on schematic)
Lug 5 and white or brown wire from coil (not on a lug): to bandswitch (shorted out on shortwave) - Primary 11.3 ohms (11 ohms on schematic)
Lug 6: To tuning cap (and 6A7 grid cap above). Top of secondary.

Lugs 2-6: 6.6 ohms on BC, 2 ohms on SW
Lugs 1-5: 0.9 ohms (.7 ohms on schematic) SW primary (mine was open - rewound).

Read this page on my website - it should give you some help, as it documents all of the changes made to Model 60 over the years.

http://www.philcoradio.com/tech/60evol.htm

[Danny]

So, if I've got this right this is what I have....

[Image: http://i958.photobucket.com/albums/ae66/...nacoil.jpg]
(click to enlarge)

Thank you sir....Now I can see whats going on.....Am I glad I checked in at the Phorum....

(edited by site admin to show picture)

[davemc]

Your drawing looks OK. I'm not sure about the order of lugs 3 and 4 (but it does not matter either). And the 10K resistor is in parallel with the Broadcast Band primary at all times, and is shorted out along with the BC primary on Short Wave (at least in my radio).