[time-nuts] time-nuts Digest, Vol 101, Issue 152

Arthur Dent golgarfrincham at yahoo.com
Mon Dec 31 03:18:45 UTC 2012

Bob Camp-
"A quartz crystal in insensitive to magnetic field. This being Time Nut's that's 
not the whole story. Ferrite core inductors can indeed exhibit a bit of static 
mag field sensitivity. Your OCXO may or may not have some in it."

"Precision crystals have clips made from nickel. The posts are likely Kovar. 
That's been true for a *long* time. Neither one is very magnetic. Both likely 
are hard enough to be even less magnetic than they might be."

I've had a Manson Lab RD-180 running for about 35 years other than short 
down time to change batteries. I've always kept it oriented in the same 
direction once I initially adjusted it because I had read that the earth's 
magnetic field would cause a small frequency shift in the crystal frequency. 
I took this at gospel and never looked into the subject any further. After 
seeing this thread (that has now lost it's original title) I did a quick search 
and found plenty of references including this one that goes into detail about 
testing that was done to quantify this effect. The section "VI Conclusion" is 
a good summation.



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