[Milsurplus] LM/BC-221 stability

[Larry]

I now have my LM-14 freq meter wired up and heated up as well.  One of 
the things i've been watching the past few days is the stability of it 
when calibrated or in the Calibrate mode.

I notice that even with a good regulated power supply, i can set the 
voltage to anything in the 200V range but presently its setting at about 
225V for plate and 24V for the filament.  It still has some drift.  My 
question is, "how long after the unit was calibrated to a particular 
check point did the techs wait before going back and rechecking it"?  
Was it allowed to drift 1 or 5 or however many KC before they were 
concerned or did the do it regularly, say every 5, 10 or 15 minutes.  
What would the requirement have been?  Saying that they only used to to 
check one frequency on a bunch of receiver as an instance?  Course if 
they were moving it from one freq to another i'm sure they rechecked the 
Cal every time the moved it to a new freq.

I'd think that with the wide bandwidth of the receivers that even if it 
was off several KC it wouldn't have been a major item.  Also, how far 
off frequency do you think a receiver would have had to be before it was 
reported to the main crew? I think it was said on here before that 
sometimes crew members "diddled" with the tuning if they weren't hearing 
other transmissions like they thought they should. Another factor to 
consider.

I've not yet put a freq counter on it to watch and see how far it moves 
but that is coming up.
Otherwise i think it's pretty reliable, if you leave the B+ on.

Larry
W0OGH