[Milsurplus] LM freq meter calibration book accuracy

[John Hutchins]

My two cents-
Turn the meter on wait 30 minutes.
Slap a frequency counter near by and you will note that it rises and 
falls either side of the mark, setting <= ~100hz on the primary band,  
by observing the digital frequency counter; Yes is does drift up and 
down but the drift is slow, over a ~20 minute period.   This may be due 
to outside air getting into the unit through the phone jack, among other 
places.  That being said the settings are right on if the reference 
crystal is adjusted correctly.  I have two LM-13's and two BC221-AK's

I compare this to my HP 8601A the drifts all over the place no mater how 
long I let it warm up. Setting on the desired frequency in the lower 
bands is a real challenge to say the least.

Forgot, was it Clete,  who described wrapping the LM or BC221 unit in a 
heavy towel; that makes a lot of sense.  This would cut down on the air 
flow exchange with the outside air and limit any drift... I'm going to 
try this trick on my HP8601A  see if a heavy towel will quiet the 
drift.  Kind-a like a BBQ smoker.... an even temperature....

Hutch