03-21-2024, 07:51 PM
Here's how I see it. The ant coil is a red herring so far, I'm still back at the osc and 1st IF trans. Think of it like this. The 6A7 is pentagrid converter tube but inside it's a triode (osc bottom section) and pentode for the ant or rf section stacked on top of each other.
Pins 4,5, and 6 are all connected to the osc circuit. Pin 4 is the "output" of the osc in that it radiates throughout the tube. The grid cap (grid 4) has the signal from ant circuit. Inside the tube these two signal are being mixed together but there are three resulting signals at the mixer's output. If the set is tuned to 1000kc for instance you'll have a signal at 1000kc, 1460kc (in your case) and at 460kc. Philco I think is the only company that used 460kc IF's from late 1932 till '38. Then for a few yrs it was 470kc and finally 455kc in the beginning of the '40 season. By the late '30s 455kc was the standard but should always check the paper work to be sure.
So it's pretty important that IF stage is working properly to discriminate and pickup only the signal at 460kc . All of the trimmer for the adjustment of the IF should a pronounced peak. I like to feed the signal thru the grid of the mixer for the align of the IF rather than connecting it to the transformer. The generator tends to load the circuit which throws the alignment out a little.
If you have a spare 455kc IF input transformer I'd give that a try and see if it will tune up 5kc. Even one from an aa5.
The resistance measurements of coils don't really mean much, unless they are suppose to be a low resistance and read very high. Coils are all about inductance, Q, and resonance.
Pins 4,5, and 6 are all connected to the osc circuit. Pin 4 is the "output" of the osc in that it radiates throughout the tube. The grid cap (grid 4) has the signal from ant circuit. Inside the tube these two signal are being mixed together but there are three resulting signals at the mixer's output. If the set is tuned to 1000kc for instance you'll have a signal at 1000kc, 1460kc (in your case) and at 460kc. Philco I think is the only company that used 460kc IF's from late 1932 till '38. Then for a few yrs it was 470kc and finally 455kc in the beginning of the '40 season. By the late '30s 455kc was the standard but should always check the paper work to be sure.
So it's pretty important that IF stage is working properly to discriminate and pickup only the signal at 460kc . All of the trimmer for the adjustment of the IF should a pronounced peak. I like to feed the signal thru the grid of the mixer for the align of the IF rather than connecting it to the transformer. The generator tends to load the circuit which throws the alignment out a little.
If you have a spare 455kc IF input transformer I'd give that a try and see if it will tune up 5kc. Even one from an aa5.
The resistance measurements of coils don't really mean much, unless they are suppose to be a low resistance and read very high. Coils are all about inductance, Q, and resonance.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
