[time-nuts] Input voltage for Zeeman on 5061A

John Ackermann N8UR jra at febo.com
Sat Jan 22 16:55:05 EST 2005


Brooke wrote:

>>
>>I'm curious as to how close you get using the Zeeman method.  Do you 
>>have any data showing Zeeman frequency vs. Source frequency for HP 
>>and/or FTS tubes?
>>
Based on my experience today, using the dinky built-in meter the closest 
I could place the peak was within about plus or minus three minor 
divisions.  Based on a sensitivity of 8x10e-14 per minor division, that 
would be about +/-2.5x10e-13.  I'm now measuring against a Z3801A and 
Loran-C to see how close I am; I need several hours more data before I 
can draw any conclusions.

By the way -- following up on a posting from Poul-Henning a while ago, 
I've been doing some reading about the Loran Modernization Project and 
it looks like (a) Loran will be around for a while, and (b) it's 
becoming a more useful frequency calibration tool.  They've already 
replaced the old Cs at all LORSTAs with three new 5071As, and there's 
new time/frequency equipment being installed that improves the 
performance in a number of ways, notably replacing the old 20ns step 
adjustments with a more gradual slewing of time.  And, the old 
transmitters are being replaced with solid-state units that should 
improve reliability.

Fortunately, the station nearest me, Dana, Indiana (8970-M) has the full 
complement of new stuff installed.  I hope to do some real-time 
intercomparisons of Loran and GPS to see how the two stack up these days.

John





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