05-26-2022, 08:20 AM
Yesterday, I sat down and took a good look at the chassis of this radio.
First, I checked the loop antenna connections - everything was ok there (it had not been disconnected).
I had not replaced some of the resistors. I remembered that this radio had the appearance of having lived a rough "life". Or, to be crude, it appeared to have been "rode hard and rode often".
Therefore I set out to replace many of the resistors I had not replaced initially.
When I was done, all the resistors save two (R204, which had been replaced in the past, and R403 which was mounted on the selector switch) had been replaced. In addition, I went ahead and replaced four of the mica capacitors in the tuning circuit (C401, C402, C404 & C405). I did not trust C405 as it looked like a "dogbone" resistor with thin, fragile leads.
After replacing those parts, I tried the radio out again yesterday evening.
Was it working correctly now?
You be the judge...
[Video: https://youtu.be/UNY8PF4Qay8]
The first station you hear is WITZ in Jasper at 990 kc. The 1280 preset was silent, but then my home SSTRAN comes in loud and clear at 660 kc. No longer did the volume control need to be at maximum to hear my SSTRAN. Most importantly, the sound was no longer garbled with hum modulation!
Lesson remembered: In an old AC/DC radio such as this that has obviously seen heavy use, don't stop at replacing the paper and electrolytic capacitors. Replace the old resistors as well, and mica caps as needed.
Now I will touch up the set's alignment and make sure the presets are tuned correctly and working, after which I will return the chassis to its cabinet and this project will then be complete. I may, or may not, replace the speaker anyway since it has a couple small holes in the cone. Nevertheless, it sounds ok now.
Thanks for looking and commenting.
First, I checked the loop antenna connections - everything was ok there (it had not been disconnected).
I had not replaced some of the resistors. I remembered that this radio had the appearance of having lived a rough "life". Or, to be crude, it appeared to have been "rode hard and rode often".
Therefore I set out to replace many of the resistors I had not replaced initially.
When I was done, all the resistors save two (R204, which had been replaced in the past, and R403 which was mounted on the selector switch) had been replaced. In addition, I went ahead and replaced four of the mica capacitors in the tuning circuit (C401, C402, C404 & C405). I did not trust C405 as it looked like a "dogbone" resistor with thin, fragile leads.
After replacing those parts, I tried the radio out again yesterday evening.
Was it working correctly now?
You be the judge...
[Video: https://youtu.be/UNY8PF4Qay8]
The first station you hear is WITZ in Jasper at 990 kc. The 1280 preset was silent, but then my home SSTRAN comes in loud and clear at 660 kc. No longer did the volume control need to be at maximum to hear my SSTRAN. Most importantly, the sound was no longer garbled with hum modulation!
Lesson remembered: In an old AC/DC radio such as this that has obviously seen heavy use, don't stop at replacing the paper and electrolytic capacitors. Replace the old resistors as well, and mica caps as needed.
Now I will touch up the set's alignment and make sure the presets are tuned correctly and working, after which I will return the chassis to its cabinet and this project will then be complete. I may, or may not, replace the speaker anyway since it has a couple small holes in the cone. Nevertheless, it sounds ok now.
Thanks for looking and commenting.
--
Ron Ramirez
Ferdinand IN
