[Milsurplus] BC-221 update the 1000kiHZ reference crystal does matter.

[John Hutchins]

Good evening all-
The the 1000 KHz Crystal is the key component.  I had one stuck in the 
tube drawer - Pugh -  Also purchased one from a list member - Thanks by 
the way.
Both crystals were crimp sealed no screws on the base. 
The measured variation in frequency of the crystal output varied as the 
crystals warmed up.
Same Unit no adjustment to the trimmer capacitor what so ever.
With increasing temperature inside the unit the crystal circuit drops in 
frequency.
All measured over a 4 hour period cabinet starting temperature approx 72 
deg F. Measured temperature rose to ~90 Deg  as measured under chassis 
near crystal socket using a thermal couple wire digital meter.
Crystal can with screws varied -25 hertz  markings DC9-P 4X8519 (in unit 
when purchased).
Crystal sealed varied -6 hertz markings DC-9-A1 Ser.No. 578 3-56 (found 
in tube drawer).
Crystal sealed varied +2 hertz Clark Crystal DC-9 (list member).
All measured with a Fluke 1953A.

Looks like I need to clean the "crystal" contact surfaces in the one I 
can open DC9-P 4X8519 humph.

Later
Hutch