07-02-2014, 10:20 PM
It's still humming, but...
I followed the advice given here and picked up a frequency counter. I checked the counter by feeding the generator signal on top of several AM stations, then switching the signal to the counter. The counter seemed to be accurate throughout the AM frequencies.
[Image: https://lh3.googleusercontent.com/-B56dt...520506.JPG]
Then I redid the AM alignment on the Philco 645, using the counter to determine the signal generator settings. The result was that the tuning at the high and low ends of the band was sharper then it had been...BUT in the middle of the band I get these horrendous noises. I've run into this before with another AM set, and I'm curious about the cause and the resolution.
This is what it sounds like (link should take you to a 30-second video):
https://picasaweb.google.com/coldrb/Jul1...directlink
I could eliminate the noise by readjusting the compensating condenser for the detector, but the next time I turned the set on, the noise was back.
So, what do you think? Is this a known phenomenon?
I followed the advice given here and picked up a frequency counter. I checked the counter by feeding the generator signal on top of several AM stations, then switching the signal to the counter. The counter seemed to be accurate throughout the AM frequencies.
[Image: https://lh3.googleusercontent.com/-B56dt...520506.JPG]
Then I redid the AM alignment on the Philco 645, using the counter to determine the signal generator settings. The result was that the tuning at the high and low ends of the band was sharper then it had been...BUT in the middle of the band I get these horrendous noises. I've run into this before with another AM set, and I'm curious about the cause and the resolution.
This is what it sounds like (link should take you to a 30-second video):
https://picasaweb.google.com/coldrb/Jul1...directlink
I could eliminate the noise by readjusting the compensating condenser for the detector, but the next time I turned the set on, the noise was back.
So, what do you think? Is this a known phenomenon?
