Philco 60 code 121 IF's - Printable Version
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RE: Philco 60 code 121 IF's - Jimradio - 03-22-2024
I took the antenna coil out and repaired the .7 coil, the radio improved a little.
Thanks for the reply's, great help.
RE: Philco 60 code 121 IF's - radiorich - 03-22-2024
hello jim,
That is good news !
Sincerely Richard
RE: Philco 60 code 121 IF's - Jimradio - 03-22-2024
Thank you Terry.
I temporally wired in an IF from a Philco 49-506 and peaked it to 460khz the BC band came booming in. I have two of these IF cans. Now for some advice, do I retro fit that same IF can the chassis or do you have another idea.
I do not get or hear anything on the SW band, no noise. Not really too concerned about it but it would be nice to fix it.
Love this forum.
Jim
RE: Philco 60 code 121 IF's - Radioroslyn - 03-22-2024
I'm not a chassis hacker upper. The repairs I do I try to make look like they are period correct. I would take out the old IF transformer and mark the wires, it may come in handy later.
Philco made a billion of the model 60's from '33 to '36. I'd say it's one of the most asked about sets on the forums. The later sets may have the trimmers incorporated with the coils in the can so this would require some fab work to use those in the stock early setup. Seems like it shouldn't be too hard to find a parts set.
Or maybe use a Ktran transformer, that's one of those 3/4"x 3/4"x 3" tall 455kc IF jobs that were used in the '50s. Solder a tab onto the brass clip that holds it in place and stick it in the can where your bad one was. Use the tab as a bracket to screw it down to the chassis with. This is after aligning it to 460kc.
I'll mention in passing that 1st and 2nd IF xformers are not the same and don't make good substitutes for each other. The 2dary windings different impedance's. 1st IF is high as it's designed to match the control grid of the IF amp tube. But the 2nd IF is low as it's designed to match the diode load of the detector. You get better performance by using the the proper transformer as in was designed for.
On the sw check the osc for a signal at 460kc above the dial setting w/your counter. You may find that the trimmers for the sw band are so out of alignment that the osc has quit. So it could be something simple that doesn't make your hair smoke!
RE: Philco 60 code 121 IF's - Jimradio - 03-29-2024
Sorry I didn't get back here sooner.
I have the BC band working but not the SW band, very quiet no noise no static nothing. All I can do is send 460 khz from the signal generator, I can hear that. I tried any frequency in that band from the generator to the antenna or the cap on of the 6A7, I can't hear it.
On the schematic it shows two #5 antenna adjustments and two #6 osc adjustment on the tuner, the tuner has just one antenna trimmer and one osc trimmer.
On this radio there are no SW trimmer adjustments.
I did replace the #11 1400pf cap. on the osc to the band switch, no help.
RE: Philco 60 code 121 IF's - RodB - 03-29-2024
Hi Jim,
Those are symptoms of an oscillator's failure to oscillate or oscillating at the wrong frequency. Since there are very few parts in this circuit, recheck the value of resistor 10 and I assume you replaced the 2 caps which make up part 20, which is a dual 0.1 mfd cap. Be suspicious of part 13, 110pf. When it comes to oscillators I narrow my tolerance on part values because it seems some oscillators are designed on the edge of whether they run or not. Any variation in part value may kill it. Also, do more checking on component connections, especially dirty switch contacts and tube socket pins. Try replacing the 6A7. You should see 2-4 volts on pin 4 of the 6A7 if the oscillator is running (use a DVM or VTVM). Clean the band switch contacts.
RE: Philco 60 code 121 IF's - Jimradio - 03-29-2024
Thanks RodB, I'll check this out.
RE: Philco 60 code 121 IF's - Jimradio - 03-30-2024
Not working yet. R10 I have a 50K, 4 caps make up #20 all changed the .09 are .1, .05 and a .5, Cap #13 is a new 110pf, a crossed pin #1 and #3.
On the 6A7 pin 4 you said 2-4 volts but the Philco 60 service bulletin shows it should be 180 volts I have 140 volts I changed the R10 from 32K to 27K to get more voltage. It was 102v.
Remember this radio works on BC band.
Here is what I found, when the band switch is moved to SW the voltages drop.
On the osc coil this is what I found
BC band ------ SW band
Pin #1 22v ------- 3.3v
Pin #2 145v ------- 95v
Pin #3 149v ------- 95v
Pin #4 26 -------- 3.3v
Pin #5 26 ------- 3.3v
Top wire 22.9 ------ 3.3v
On the 6A7 voltages
BC Band ------ SW Band
Pin #2 255v ------ 254v
Pin #3 80v ------ 59v
Pin #4 140v ------ 92v
Pin #5 24v ------ .48v
These readings are from K #6 to pin
I have not tried another 6A7, I don't have a new one only used.
I have checked and rechecked wiring, but something is dropping the voltage when the band switch is in SW mode.
RE: Philco 60 code 121 IF's - Jimradio - 04-04-2024
The BC band works just fine, cannot get the SW band to work, no oscillation. When the band switch is turned to SW the voltage on lug 3 & 2 on coil and pin 4 on the 6A7 tube drops about 40 volts. This is the secondary coil. On the 6A7 tube there is continuity between pin 6 & 5 of 50K (R10). When the 300 ohm resistor (R9) is lifted removing ground, there is no ground from pin 5 or pin 6 to ground.
If the lugs 4 & 5 on the coil are shorted the voltages drops, if the cap (10) and lug 1 are shorted of the coil the voltage will drop.
I rewound with new wire the secondary coil, lug 2 & 3 (3.4 ohm), did not change anything.
There are 4 switches on the band switch, the antenna switches do not cause the voltage to drop only the switches on the osc coil.
The B+ voltage is not affected when in SW mode, at the 32K (R14) only after the resistor is there a voltage drop.
I think there may be a problem in the osc coil, but what.
Thanks
