Philco 60 Squealing - Printable Version

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Philco 60 Squealing - dconant - 11-25-2024

I have recapped and replaced out of tolerance resistors and so on. Radio plays nicely on fairly strong stations. The problem is weak stations produce squealing when tuned in. I have touched and moved many wires which make the squeal go away but just moves up or down the scale a tiny bit while still on the same weak station. I have swapped out the oscillator, IF and detector tubes with no change. Grid wire to the detector is inside the tube shield. Like I say the stronger stations don't have this problem. An alignment has been done but noting the antenna trimmer does nothing. Signal generator set very low. Any idea what is causing the squealing?

Thanks,
Dan

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RE: Philco 60 Squealing - Chas - 11-25-2024

All correct shields must be in place, all tubes correct no subs of any kind.

Check any soldered, riveted ground connections, DC measures of ground cannot detect a ground that has hidden corrosion, solder those riveted grounds to the chassis.

An open coil or a coil with resistance higher than the published specification.

A band switch that has been treated with a lubricant may be leaking. Sam lube on tube sockets can cause this. Clean all excess lube off with 91% alcohol, gently blow dry do not power until all alcohol is gone.

Check the AVC circuit for stray leakage and possible incorrect parts in the circuit.

Do, look for stray wire snips and larger solder blobs causing shorts. A misplaced bypass cap can be problematic too...

Look for calibration errors, a mica may be failing or failed. Calibration is often a clue other than mis-alignment.

GL

Chas

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