08-13-2023, 09:45 PM
Lots of work on this set this weekend. First off, to diagnose the oscillator problem. I replaced all the paper caps, and the suspect 50k resistor, and the paper caps. Still no stations, and now there was an LF instability in the whole set as soon as the tuning cap was more than half open, with the set blowing raspberries from the speaker. At the end of the day, I returned to checking wiring and component values from the schematic, and found a broken wire from the converter tube grid circuit to the oscillator section of the tuning cap. OK, something to go on, and a good end to the day.
Today I removed the tuning cap, which was needed anyway, to replace the rubber bushings. I punched these out of some silicone foam, and added new wires to the cap #28 enameled wire, with cloth insulation slipped over it was a close match to the original. With this, I finally had some reception, but still a very unstable receiver. Whistles on stations up to about 100 on the dial, after that raspberries from the speaker, on either band. Eventually I tracked this to a bad solder joint connecting one of my restuffed caps. With that restored, I was able to align the radio and it really pulls in stations.
Pics tomorrow,
Ed
Today I removed the tuning cap, which was needed anyway, to replace the rubber bushings. I punched these out of some silicone foam, and added new wires to the cap #28 enameled wire, with cloth insulation slipped over it was a close match to the original. With this, I finally had some reception, but still a very unstable receiver. Whistles on stations up to about 100 on the dial, after that raspberries from the speaker, on either band. Eventually I tracked this to a bad solder joint connecting one of my restuffed caps. With that restored, I was able to align the radio and it really pulls in stations.
Pics tomorrow,
Ed
