Early film resistors looked like inductors,due the to the "clever" way they adjusted their values------a long spiral was cut into the film.
What do you mean 'early'? All the axial metal film resistors I ever broke open are constructed like that. Are there ones that are not? Sources?
I'm trying to think of what I can replace carbon composition resistors with, in general in this radio. To avoid exactly that inductance effect.
I have stock of all values in 0805 surface mount resistors, but soldering little wires on and using like axials won't be reliable. Solder fractures and in some cases, insufficient dissipation.
For that reason,carbon composition resistors hung around for longer than they might otherwise have done.
Yeah, I knew relatively flat impedance vs F was their advantage. But I don't want to buy a range of carbon composition resistors!
The values quoted are close enough to not worry---the design values may well have been 4k,3.5k,5k,& 300 Ohms in the first place,with the nearest standard values selected on test.
In this crystal oscillator, I think they actually are the problem. It's behaving like the loop gain is *just* a little bit below unity, until it warms up. There's still one other thing to check though. Not the crystal, that's definitely OK.
On the osc-buffer A1 module, I suspect R2 & R4, which are both drifted high. Still to check Q1's gain. Plus maybe T1 is mis-adjusted due to the slug being loose.
Another question. What would be a good inductor slug-locking paint, for use in a crystal oven? The one originally used has decomposed. I'd normally use nail varnish, but I don't know what it would do when hot. Silastic won't do because it's flexible.
Schematic, 2000x1300: