[R-390] "A" stability

[Perry Sandeen]

Hi.
Wrote: Myonly real point was that the R-390 needs about a day in a typical rack tosettle down

howevermuch it’s going to settle. I have no illusion about a 390 holding 0.01 Hz for15 minutes.


 

That's  true for a "stock"  "A".




Dallas Langford did a mod to his "A" BFO and reduced its drift to less than 1 Hz per hour measured with a Rb referenced counter.




Theoretically, one could change all the "A" ovens to proportinally controlled units and put  a buffer on the 17MHz oscillator to prevent the 1 st mixer AGC action pulling it and get some awsome frequency stability numbers.




But then what is the end purpose to the effort?




I guess it depends how "nuts" we are with our hobby.




Regards,




Perrier