09-21-2015, 06:56 PM
I tried it out and the radio works...in a manner of speaking. I can tune broadcast signals from different stations on different parts of the dial, but the volume is quite low. I suppose the good news is the antenna, IF, and oscillator coils are all good (verified by DMM measurements as well). FC measures at 1200 ohms, but should be 1000 ohms. Is that a problem? The OT measures 400 as it should.
I'm using about 15' of wire for an antenna and I have a ground, so almost certainly I have an output stage issue, right? I'm considering pulling the volume pot and dismantling it for a good clean up. It turns with more effort than I'm used to, but the switch works. It measures at 500K. I have another 500K volume/on-off switch around here somewhere, maybe I'll sub it in instead.
On a dim bulb test, a 60 watt bulb goes bright for a second, dims, but has a moderate glow-not bright by any means, but there. I'm trying not to run on direct mains for longer than it takes to verify that I can tune a signal in and that the volume is too low. In fact, not at all unless I have something in the output stage I change that is significant enough to warrant another test.
How crucial to output volume is C32? I'm using some salvaged mica caps there, and I'm not certain about them. I'm also kicking myself because when I dug out the tar on that one the caps turned out to be old-fashioned mica caps, so they were likely still good.
By the way, some past owner put in a home made loop antenna in the cabinet (this is the console model). Is that what the red and black terminals on the back of the chassis are for? The way the antenna posts look on the schematic, it seems like this set would work with a dipole antenna as well, but I'm honestly not all that knowledgeable about antenna issues.
I'm using about 15' of wire for an antenna and I have a ground, so almost certainly I have an output stage issue, right? I'm considering pulling the volume pot and dismantling it for a good clean up. It turns with more effort than I'm used to, but the switch works. It measures at 500K. I have another 500K volume/on-off switch around here somewhere, maybe I'll sub it in instead.
On a dim bulb test, a 60 watt bulb goes bright for a second, dims, but has a moderate glow-not bright by any means, but there. I'm trying not to run on direct mains for longer than it takes to verify that I can tune a signal in and that the volume is too low. In fact, not at all unless I have something in the output stage I change that is significant enough to warrant another test.
How crucial to output volume is C32? I'm using some salvaged mica caps there, and I'm not certain about them. I'm also kicking myself because when I dug out the tar on that one the caps turned out to be old-fashioned mica caps, so they were likely still good.
By the way, some past owner put in a home made loop antenna in the cabinet (this is the console model). Is that what the red and black terminals on the back of the chassis are for? The way the antenna posts look on the schematic, it seems like this set would work with a dipole antenna as well, but I'm honestly not all that knowledgeable about antenna issues.
Charlie in San Antonio
