09-16-2008, 10:14 AM
To adjust the IF can compensators you would inject the signal though a cap into terminal 4 of the antenna terminal strip in the back of the radio. Terminal 1 goes to the output xformer, so use that one to connect a high impedance meter (also through a capacitor) to measure signal strength while you move the compensators. (You can also listen to the speaker volume.) Underneath the parts list, the Riders page gives a table and some notes to explain all of this, but I'd still advise reading the chapter on alignment in Elements of Radio Servicing before tackling it.
Edited to add:
I went back and read your original questions about the functions of the compensator adjustments. As near as I can tell, they are as follows:
29A, 29B, 31A, and 34A on the IF cans are to adjust the resonance of the interstage transformers to exactly the intermediate frequency of 455 KHz. If any one of these is off, it will reduce your sensitivity by filtering out the intermediate frequency.
4A, 4B are to tune the antenna for the broadcast band and shortwave band, respectively.
4, 4C, 4D, and 4E are to adjust the tracking of the oscillator for the various bands so that the dial pointer will show the right frequency at every point. If these are out of adjustment, you can adjust the pointer to one station's frequency on the dial, but it will point to the wrong frequencies as you track above and below the one station you set.
Except for the IF cans, these adjustments should be made with the chassis in the cabinet and the loop antenna connected, injecting the signal generator frequency indirectly by making a loop of a few turns of wire and setting it up close to the radio's loop antenna. Then follow the instructions in the Rider's manual in the table and the notes under it. Elements of Radio Servicing Explains this loop antenna connection in Chapter 22, page 415.
Edited to add: Antique Electronic Supply has 41 tubes ST style 50% off until September 30. I'd replace those bad ones you have ASAP.
Edited to add:
I went back and read your original questions about the functions of the compensator adjustments. As near as I can tell, they are as follows:
29A, 29B, 31A, and 34A on the IF cans are to adjust the resonance of the interstage transformers to exactly the intermediate frequency of 455 KHz. If any one of these is off, it will reduce your sensitivity by filtering out the intermediate frequency.
4A, 4B are to tune the antenna for the broadcast band and shortwave band, respectively.
4, 4C, 4D, and 4E are to adjust the tracking of the oscillator for the various bands so that the dial pointer will show the right frequency at every point. If these are out of adjustment, you can adjust the pointer to one station's frequency on the dial, but it will point to the wrong frequencies as you track above and below the one station you set.
Except for the IF cans, these adjustments should be made with the chassis in the cabinet and the loop antenna connected, injecting the signal generator frequency indirectly by making a loop of a few turns of wire and setting it up close to the radio's loop antenna. Then follow the instructions in the Rider's manual in the table and the notes under it. Elements of Radio Servicing Explains this loop antenna connection in Chapter 22, page 415.
Edited to add: Antique Electronic Supply has 41 tubes ST style 50% off until September 30. I'd replace those bad ones you have ASAP.
John Honeycutt
