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Have tracked down a 2nd Philco 66- {different cabinet} that is almost all original and it works. I have been comparing the two with voltage readings at all tubes. The original is wired exactly like the new one but voltages are higher in the original.
On the original- soldered in the wire from white of 42 to 28 and 29 terminal. Hum on center tap of vol. control that is controlled by vol. control. Set up signal gen. on 460 and went through antenna- nothing through speaker.
Touched grid cap of 6A7-nothing
Touched grid cap of 75- nice clear tone.
Suggestions?
Thanks,
Joe
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First of, Jph, injecting if freq. in antenna is not supposed to produce any tone. Antenna is connected to the RF amp an the tuned circuit will only let through the frequency it is tuned to. In prder for the IF to prduce the tone you need to feed it to the input of the IF filter, or output of it, that is the detector input.
This is why radios are tuned to stations' freqs.
Should've said that earlier when it was first suggested to you.
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The model 66 doesn't have a rf amp but injecting the IF signal into the grid cap of the 6A7 will work fine. When you connect to the ant post the signal has to go though a tuned circuit that isn't resonant at the IF frequency hence it will attenuate the IF signal.
Terry
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I did remove the grid cap of 6A7 and injected 460 from there. Got good tone. Did adjust the four trimmers for max. Good start.
Just to try I hooked up antenna through ant. clip- got no channels but did get interference from shop lights.
Have to adjust wave trap and tuning condensor-- any pointers? I tried following the alignment procedure but am confused on this.
You guys have certainly taken me much deeper into this than I was capable of.
Will continue work this weekend but feel like we're getting close.
Thanks,
Joe
(This post was last modified: 05-31-2012, 08:21 PM by
jph14.)
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So what happens if you inject a 1000kc signal into the ant post and tune the set around 1000kc?
Terry
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My bad Joe, sorry, yes if you inject from the antenna, you need to set your generator to a radio frequency then check at that frequency. Thanks gang for correcting me. I was thinking about injecting in the IF stage. Keep going Joe, it's going to work. Follow Terry's advise and see if you pick up the tone around1000 on your dial. When you find it, then you can adjust your osc. and ant. trimmers per the directions for alignment to bring it spot on. If you can find the signal, your almost home, your oscillator is working!
Jerry
A friend in need is a pest! Bill Slee ca 1970.
(This post was last modified: 05-31-2012, 09:35 PM by
jerryhawthorne.)
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If you are going to use this to align the set it should be a bit higher in frequency like 1400kc. I picked 1000kc cause it's closer to the center of the dial, might be easier to find.
Terry
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Correct Terry, which is why I suggested to align per factory specifications. I probably was not clear.
Jerry
A friend in need is a pest! Bill Slee ca 1970.
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1400 nothing - cannot find it on the dial. Signal through the antenna clip?
Joe
(This post was last modified: 06-01-2012, 02:35 PM by
jph14.)
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Ok Take a transistor radio and place it next to the 6A7 tube. Tune it to 1500kc. Adj the dial on the Philco with it set to the BC band. If all is well at some point you should hear a hum in the transistor set. That is the signal from the local oscillator.
Terry
Bump my needle I feel like a broken record.
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Tried transistor radio near 6A7- did not get any hum from Philco.
Joe
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Did you try to adjust your Philco, as your 1500kHz may not necessarily be accurate?
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Yes. Got nothing across dial.
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Ok Double check 8, 200 ohms, 10, 50K ohms and 15, 32K ohms. Replace 14, 800mmfd.
Measure resistance from the coil side of #10 to pin 5 of the 6A7.
Measure resistance from the coil side of #10 to coil side of #14
Both should read only a few ohms. If not You've got a bad coil.
Terry
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Resistors check OK. #14- how close do I need to be - I have a 700 in stock.
Resistance from coil side of #10 to pin 5=@ 4 ohms
Resistance from coil side of #10 to coil side #14= open.
Thanks,
Joe
