01-22-2015, 02:19 PM
HI Everybody,
I restored a 19B, code 126 about a year ago with a lot of help from many people here. A week or two ago, I powered it up and found that the radio went silent below about 720 KHz. I remembered posts about the 36 tube cathode resistor (item 10) being too high of a value, and that this resistor could go to as low as 7500 ohms. At the time I did the restore I had lowered this to 10K and it seemed to work. So last week when the radio stopped working at the low end of the dial, I opened it up and put in 7500 ohms and it seemed to work fine.
Then I got this great idea that I should try another alignment. I had done this radio rather early on and I wondered if I might be able to get it aligned a little better now that I had a little more experience. I hadn't put it back together since changing the cathode resistor, so last night I tried an alignment.
I tuned up the IF cans, and also made adjustments at 1400 KHz as per the instructions. I was making modest improvements and all seemed to be going well. Then I came to the point where I was to make adjustments at 650 KHz. I set up the signal generator and tuned the dial down to '65'. The radio was completely silent. I hadn't noticed it at first, but the radio cut out at around 950 KHz. I went back and tried tweaking the IF and 1400KHz adjustments again, but no joy.
Does anyone have an idea about what I did wrong, or how to proceed? I was using very low signal strength from my signal generator.
It seemed like this was working with the change of item 10 to 7500 ohms, but now that value isn't working. No other changes were made to the radio since modifying the cathode resistor value. Radio still works above 950 or so.
Thanks in advance.
I restored a 19B, code 126 about a year ago with a lot of help from many people here. A week or two ago, I powered it up and found that the radio went silent below about 720 KHz. I remembered posts about the 36 tube cathode resistor (item 10) being too high of a value, and that this resistor could go to as low as 7500 ohms. At the time I did the restore I had lowered this to 10K and it seemed to work. So last week when the radio stopped working at the low end of the dial, I opened it up and put in 7500 ohms and it seemed to work fine.
Then I got this great idea that I should try another alignment. I had done this radio rather early on and I wondered if I might be able to get it aligned a little better now that I had a little more experience. I hadn't put it back together since changing the cathode resistor, so last night I tried an alignment.
I tuned up the IF cans, and also made adjustments at 1400 KHz as per the instructions. I was making modest improvements and all seemed to be going well. Then I came to the point where I was to make adjustments at 650 KHz. I set up the signal generator and tuned the dial down to '65'. The radio was completely silent. I hadn't noticed it at first, but the radio cut out at around 950 KHz. I went back and tried tweaking the IF and 1400KHz adjustments again, but no joy.
Does anyone have an idea about what I did wrong, or how to proceed? I was using very low signal strength from my signal generator.
It seemed like this was working with the change of item 10 to 7500 ohms, but now that value isn't working. No other changes were made to the radio since modifying the cathode resistor value. Radio still works above 950 or so.
Thanks in advance.
