In article , Uwe
writes:

Yes this is all very helpful. Indeed I was thinking that it would have taken
me a very long time to figure this out by myself, if at all.

I put another choke in there, a Hammond 1535B, the self resonant min. frequ.
is 1.3Mhz.

That should be a good one.

I guess it does take some deeper inside what parameters to look for since
this one improves things slightly but not yet altogether (slightly more
pronounced dip).

Who carries the sort of chokes you were refering to?

"Play Things of The Past" (www.oldradioparts.com) is one. Antique Electric
Supply (www.tubesandmore.com) is another. JWMiller still makes pie-wound 2.5
millihenry chokes with phenolic (no iron) cores. Check Digi-Key and Mouser.

Also google "AC1 ameco" - several websites with more info. One site I visited
(whose url I didn't save!) listed the plate voltage as approximately 325 volts.
This site also cautioned that the original grid resistor (47 K?) is way too
high, and that better results are obtained with a grid resistor of 4.7 K to 15
K. The author says the smaller value grid resistor gives less chirp.

The traditional amateur way to measure grid current is with a small lamp in
series with the xtal. "Small" means a #48 or #49 bulb - 2 volts at 60 ma. The
common #47 lamp needs 6.3 volts at 150 ma. and is way too insensitive. Small
flashlight lamps such as used in single-cell penlights may also be useful.

But the lamp should only be used for testing. Its resistance may cause chirp.

and before I forget:

CONGRATS ON YOUR GENERAL, Uwe!

73 de Jim, N2EY