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Philco 80 Alignment - Printable Version

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Philco 80 Alignment - Mike L - 01-29-2017

Now that I have a working signal generator, I'm attempting to align the set. Initially It was missing the phenolic hex adjuster on the sensitivity trimmer. I drilled and tapped a small piece of dowel for that. I followed the alignment procedure In Riders as well as the Philco publication for alignment. It will receive stations across the band but they are very sensitive. Any slight adjustment either way and it breaks into squeals and howls. You have to be dead on to receive. Adjustment to the sensitivity cap really has no effect across the band. Also the dial scale is off with reference to the station by more than 30k.c.'s. low.

For output measurement I had my VTVM set to AC volts and connected to the primary leads on the output transformer.

The signal generators output was verified with a frequency counter. Output was set as low as possible to still get a mid-scale meter reading.

When called for removing the grid clip from the Det.-Osc. and connecting the signal generator to the control grid, I just clipped on to the clip itself.

I think I'm doing this correctly, in fact the first two steps at 460k.c. was easy. Its the next two with the generator set to 1400k.c. and adjusting the antenna and HF that dosen't seem to be working correctly. Initially I skipped over those since I never did any repair work in that area, but the tuning issue with squealing and howling continued. All adjustments were made with a plastic tool I made. What am I missing or doing wrong?  Icon_confused

RE: Philco 80 Alignment - morzh - 01-29-2017

Mike

I think first you shoud turn the regen trimmer out so the radio is far from going to squeeling mode. This will likely take care of the howling and the birdies.

If they say remove the clip, it is probably for a reason. I think it is because generators like SG8 or a Philco one have no cap on the output and the attenuator pot will provide the grounding pulldown for the grid. If you keep the clip you attenuate it futher plus possibly create some unwanted resonances.

This said, it is probably not your problem.

But do take care of the regen mode first so it does not howl.

RE: Philco 80 Alignment - Mike L - 01-29-2017

Quote:I think first you shoud turn the regen trimmer out so the radio is far from going to squeeling mode. This will likely take care of the howling and the birdies.

I have backed off the regen trimmer almost to the point of no compression and everywhere in between. When I tune a station and make an adjustment to the regen trimmer the station then comes in clear. But just the slightest movement of the dial either way and it squeals and howls loudly. Slightest as is the width of a dial line. Further adjustment at that point does not help.

I went back through the procedure several times thinking that it is just so far out that I need to bring it back in slowly. Same order, over and over.

Is it possible that the oscillator coil is or maybe bad and thus I'm aligning everything wrong? I did not pull the coil in this set during the re-cap. Or maybe the regen cap?

RE: Philco 80 Alignment - KCMike - 01-29-2017

You might try moving the lead dress of the wires around when its doing said problem. Also make sure tubes good and any shields are on tight. Just a few simple things I can think of to try.

RE: Philco 80 Alignment - PAradiogeek - 02-16-2017

Are the tube shields in place?