09-16-2008, 09:57 AM
If your 41 tubes aren't very good, it would definitely reduce the volume, and it should have the same effect on every station.
If you suspect that weak signals are due to alignment, I'd try to align the IF cans first, before touching the trimmers and/or padders that are grouped on the right side of the chassis. Your IF tuning is probably way off after recapping, especially if you replaced the mica caps inside the cans. Use AM tuning for this, not one of the push button station selectors. Be sure to connect the signal generator through a cap (.1 uf, I think) to keep from putting the generator plate voltage into the antenna. You can do a rough "by ear" adjustment without the signal generator, but be sure to adjust the cans in the order 34, 31, and then 29, and then touch up with the signal generator when you are satisfied that all the tubes, components, and wiring are right. Your "by ear" adjustment can tell you whether alignment might be responsible for low volume, but you'll probably set the IF way off.
The two rows of controls on the back are both to tune the push buttons. The upper row in back are capacitors to tune in the antenna for each push button selection, and the lower row are tunable inductors to tune the oscillator for each station. Select a push button, and use the oscillator control for that button first to bring the station in, then try the antenna capacitor right above it, then go back and forth until it is as good as it gets. It can be touchy. It would be best to adjust push-buttons with the radio in the cabinet using the loop antenna. There might be an easier way, but that is how I do it.
The Riders page on Nostalgia air shows the locations of the IF compensators on top of the IF cans, and the order in which to adjust them. The copies aren't very good, so I'll make a plug for Chuck Schwark's Philco packages, which are excellent and reasonably priced. http://www.philcorepairbench.com/schematics.htm Chuck's package will probably also have more thorough and specific push button tuning instructions.
I use about a 20 foot wire antenna for my workbench. It works quite well for AM in my area, even though my workbench is in the basement. The loop in the cabinet is better. Short wave with the 20 foot wire is marginal, but good enough to tell me if the band works.
You could also grab the pdf of the book Elements of Radio Servicing at this site: http://www.antiqueradios.com/archive.shtml and read the chapter on alignment. It might also help if you read the chapter on oscillators to get familiar with the function of trimmers and padders. I lived with this book for about a month before I ever dug into a radio, but I'm still not very experienced at alignment.
If you suspect that weak signals are due to alignment, I'd try to align the IF cans first, before touching the trimmers and/or padders that are grouped on the right side of the chassis. Your IF tuning is probably way off after recapping, especially if you replaced the mica caps inside the cans. Use AM tuning for this, not one of the push button station selectors. Be sure to connect the signal generator through a cap (.1 uf, I think) to keep from putting the generator plate voltage into the antenna. You can do a rough "by ear" adjustment without the signal generator, but be sure to adjust the cans in the order 34, 31, and then 29, and then touch up with the signal generator when you are satisfied that all the tubes, components, and wiring are right. Your "by ear" adjustment can tell you whether alignment might be responsible for low volume, but you'll probably set the IF way off.
The two rows of controls on the back are both to tune the push buttons. The upper row in back are capacitors to tune in the antenna for each push button selection, and the lower row are tunable inductors to tune the oscillator for each station. Select a push button, and use the oscillator control for that button first to bring the station in, then try the antenna capacitor right above it, then go back and forth until it is as good as it gets. It can be touchy. It would be best to adjust push-buttons with the radio in the cabinet using the loop antenna. There might be an easier way, but that is how I do it.
The Riders page on Nostalgia air shows the locations of the IF compensators on top of the IF cans, and the order in which to adjust them. The copies aren't very good, so I'll make a plug for Chuck Schwark's Philco packages, which are excellent and reasonably priced. http://www.philcorepairbench.com/schematics.htm Chuck's package will probably also have more thorough and specific push button tuning instructions.
I use about a 20 foot wire antenna for my workbench. It works quite well for AM in my area, even though my workbench is in the basement. The loop in the cabinet is better. Short wave with the 20 foot wire is marginal, but good enough to tell me if the band works.
You could also grab the pdf of the book Elements of Radio Servicing at this site: http://www.antiqueradios.com/archive.shtml and read the chapter on alignment. It might also help if you read the chapter on oscillators to get familiar with the function of trimmers and padders. I lived with this book for about a month before I ever dug into a radio, but I'm still not very experienced at alignment.
John Honeycutt
