[time-nuts] Substitute GPS in a Z3801A

Matthew Kaufman matthew at matthew.at
Thu Jun 24 15:41:25 UTC 2010

I now have *two* Z3801A units which misbehave in the following way 
(which this thread reminded me of):

The GPS status says it acquires quite a few (5-6) satellites with high 
signal strength... then after a minute or two, for no apparent reason, 
it loses *all* of them simultaneously but immediately goes back into 
"acquiring" for the ones it was seeing, and a few seconds later, they're 
all back. During this time, survey (if in progress) is halted and then 
restarts and runs for a bit before halting again when it loses 
everything briefly again. Then, within days, the unit ends up out of 
lock... if I go check it, I see it doing the same thing, and when the 
satellites are being received it is in "fine frequency adjust" mode, but 
so far off the 1pps phase that it really has no hope of re-locking 
before the next time it drops and then reacquires all the satellites.

This is independent of antenna, location, and 48v power source... one 
unit apparently has been this way since I got it, the other worked fine 
for months and then developed this problem.

Without knowing more, I'm thinking it might simply be a bad GPS receiver 
board, thus the idea of trying to find a replacement, perhaps one that 
is better at staying acquired, has crossed my mind.

Matthew Kaufman

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