[time-nuts] Brooks Shera's GPS standard or HP Z3801A??

Dr. David Kirkby drkirkby at medphys.ucl.ac.uk
Mon Apr 25 05:35:25 EDT 2005

I was going to build the GPS reference by Brooks Shera


and have bought the PCB and started populating it (not much yet).

But now I am wondering if buying a used Z3801A might not be a better idea.

My thoughts are:

1) Cost - the Z3801A will probably cost less than buying all the parts 
for Brook's Standard. This is especially so, with me in the UK, where 
shipping charges on lots of small items from the USA soon add up.

2) Medium term stability - the double oven in the Z3801A might be more 
stable than an HP 18011A.

3) Flexability - Brook's standard can be customised to whatever you want.

4) Long term servicability - if one builds the standard oneself, one is 
far more likely to be able to debug it if things go wrong. One can buy a 
few of the chips, for spares, just in case one dies and becomes hard to 
get. The chips on the board are not that expensive.

5) Jitter on GPS.

6) If one needs to buy a manual on the Z3801A, that will add to its cost.

Any other thoughts ????

Dr. David Kirkby PhD CEng MIEE,
Senior Research Fellow,
Department of Medical Physics,
Mallet Place Engineering Building,
Gower St,
University College London,
London WC1E 6BT.

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