: I have been having some troubles with tuning in stations and
: keeping them tuned in. It seems like I have to keep readjusting the
: tuning. This radio uses the slugs in the coils that move in and
: out to tune the circuit. I have tried to adjust these to max output,
: but I still have to re-tune the radio. Is my problem in the oscillator?
What Don described is the right track to locate the offending component(s), but don't forget potential "cold" solder joints, or (possibly) a resistor that shifts value a bit too. It may also be a situation where there is just enough "tolerable defect" in several components, that when in the circuit they are- add up to a mild difficulty.
You may find that the voltages to the Oscillator stage (and other stages too) rise slightly over the first 30 minutes, in which case, there will be more searching to do, and in the end, you may only be able to minimize it, as some of that was expected (or should have been) by the designers.
Some shift is "normal". A set that is just turned on, may need to be "tweaked" just a little on the tuning knob after about 20 or 30 minutes. Even if you replace the worst offending componenets, some drift "may" still be encountered.
This is just one of those endearing quirks of tube equipment. That is why the manufacturers always suggest a radio be operating for at least 20 minutes before alignment. Also too, Ham radio operators who use the old "fire bottle" boat-anchors; always run them for about a half hour before even considering "keying" a transmitter.
Determine how much time and money you want to invest in solving the problem first, and if it does not come out perfect, it may just be something that you may not be able to completly remedy. I have an early Heathkit (solid state at that, too) amp that drifts a little bit within the first 20 minutes, so tube equipment is not the only type to experience the "dilema".
: Hi Wes, The tuning drift will be the oscillator drifting. I think the most likely cause will be a capacitor around the oscillator circuit or oscillator tube. If it uses AFC it could be that part of the circuit. If it's a tube I think the drift will be fairly rapid (heats up quickly) a capacitor would take longer. You might be able to track it down if it's heat sensitive by warming the components gently with a hot air gun or hair blow dryer (be careful with the heat from a hot air gun, it can be fierce). A can of freeze spray is also useful but as they're costly try the hot air first, at least to establish it is heat sensitive. If it has AFC turn it off if possible and see if that affects it. Good Luck, Don Black.
: : I have been having some troubles with tuning in stations and
: : keeping them tuned in. It seems like I have to keep readjusting the
: : tuning. This radio uses the slugs in the coils that move in and
: : out to tune the circuit. I have tried to adjust these to max output,
: : but I still have to re-tune the radio. Is my problem in the oscillator?
try a afc diode in the front end . sound like it's leaky.