[Boatanchors] Resolved: De-chirping a Globe Chief Deluxe?

[Charlie Cheney]

Thanks to all who took the time to respond to my request for help. After 
being assured that the GCD should be capable of chirp-free operation, I 
checked components in the area of the 6AG7 and found a 47K resistor that 
had drifted up to 60K. I got a significant improvement from replacing 
that as well as the 6AG7 (the one in there was "mfd for Globe 
Electronics" so presumably the original tube), but chirp was still 
noticeable especially listening to the low beat frequency I prefer for 
CW operation (~500 Hz).

I measured the plate and screen voltages on the 6AG7 and found it was 
operating well above the max rating for screen dissipation. (This 
appears to be as-designed, I'm guessing as an economy measure to keep 
down the cost of the resistive divider?). Worse, the screen voltage was 
changing from 380V key-up to 240V key-down. Regulating the screen 
voltage at 150 with an under-chassis OA2 pretty much cleaned up the 
remaining chirp, without using any non-period components or making any 
mechanical changes, so we're good to go.

Thanks again for the help. I hope to make a lot of contacts with this 
old timer on SKN.

73,

Charlie K1LDZ