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Philco 42-327 no reception on the three Bands - Printable Version

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RE: Philco 42-327 no reception on the three Bands - RodB - 06-21-2020

Chances are slim that you will find a replacement coil so you will have to either find the break and repair it or rewind the section that has the break. When handling the coil be aware that the BC coil is on the same form.

We'll have to leave the B+ where it is. Maybe someone else has a suggestion to lower it slightly and what effect it has if left where it is.

Resistor 34 is fine as long as the resistance is what the schematic calls for.

The noise on BC band is from outside sources, mostly from small power supplies like wall warts, modems, TVs, computers, florescent lights, etc. All these devices are transmitting noise to your radio antenna and some is canceled by the circuitry, some gets through. You'll find many discussions here on this topic.

You'll need an rf signal generator to do an alignment properly but you can do it by ear by listening to a distant station and tweek the IF coils slightly one at a time for the loudest and clearest volume.

Right now focus on the SW coil. Like Terry suggested, find out where the break is, inspect the windings for the break in the wire, then figure out how to fix it.

Rod

RE: Philco 42-327 no reception on the three Bands - ascion90 - 06-21-2020

Rod, Terry 

This is my first radio repair and for me the Broadcast that now is working is a great success. 

The operations on the Oscillator coil you described are complex for me and I prefer to wait or making some experiences on some other coils to repair ( or broke...) without a radio, before working on this. It is the same of the broadcast and if I will do something wrong Also the Broadcast will be lost. Maybe on ebay someone will sell this Oscillator in the future and I will try to change it.

Before reassembly the case I will wait if there are suggestions about the High voltages . 

Rod can you explain better to me the procedure to make the alignment manually? 

Thanks

CAmillo

RE: Philco 42-327 no reception on the three Bands - RodB - 06-22-2020

OK, so much for SW. I'm not sure if you have an alignment procedure, my schematic doesn't have one. You have 3 IF transformers, 24, 29 and 35. They are the square metal cans on the chassis. Each transformer can be tuned by adjusting the variable capacitor at the top of the can. Can 24 also has a tunable core but you probably don't have the special tool needed.

Tune in a distant station, one that has a low noise level. Turn up the volume. Start with 35 by adjusting slightly the capacitor with a small screwdriver for the loudest volume. You should find that tightening and loosening the screw slightly will produce a peak in the volume. Next, do the same for can 29, then 24. Don't do this if you don't understand what to expect. You could detune the transformers.

The IF frequency is 455khz and this is the resonant frequency of each transformer. Normally there is 2 transformers in a radio. With 3 in yours you should have better selectivity.

Let us know how it goes.

RE: Philco 42-327 no reception on the three Bands - ascion90 - 06-24-2020

Hi Rod,

Thanks for the instructions. I did what you suggested and everything is tuned now with the right level of signal for most of the stations. Probably it is not perfect but it is enough now.

During the weekend  I will reassemble the case and I will post a picture.

I will wait in the next months if someone will sell an oscillator and I will reopen the project for the SW band.

Thank you so much to you and Terry for all the support 

Camillo

RE: Philco 42-327 no reception on the three Bands - ascion90 - 07-03-2020

Hi,

I finally re assembled the case everything is still working.... but the SW band due to the Oscillator coil. I learned that after the recap I must check all the coils continuity before other troubleshootings.
Thank you so much again for all the great suggestions.

 In attach some picture.

Camillo

RE: Philco 42-327 no reception on the three Bands - RodB - 07-03-2020

It displays very nicely, excellent job!