[time-nuts] Advise on building a DIY GPSDO?
dlewis6767
dlewis6767 at austin.rr.com
Mon Apr 4 20:48:13 EDT 2016
Lots' of help herein; ...but, also lots' of nay-sayers, too.
Don't let the nay-sayers scare you.
A VERY accurate, newbie-based, GPSDO can be built with minimal
investment or cost.
It's not hard at all. Just Do-It. Mistakes allowed.
I have built two GPSDO's from scratch. Both worked very well against
each other measured with an HP 5370B; against my rubidium; as well as
my cesium.
Just look at it at the 'building-block' level. (no real need for an
embedded computer unless you like code more so than dips. :-)
1. Get a good, used, GPS receiver with a 10Khz output.
2. Get a good, used, 10MHz OCXO with a voltage control.
3. Design a simple divide-by-thousand divider.
4. Exclusive-or these two using a 4046 PLL (comparator 1)
5. Design a voltage tracking / filter to match the OCXO control
requirements.
6. And, ...ta-dah;
7. You have a 10MHz, bench frequency standard that will rival all
others; and the best part....you designed and built it!
8. NOTE: Take the unused, SR flip-flop output of the 4046 PLL and
connect a small, analog, milliampmeter. It will swing back and forth
trackin the XOR function until your GPSDO 'locks'; then become
stationary.
Basic? Yes! Over-simplified? Probably.
But it will work and you will feel like you accomplished your goal of
'doing-it-yourself'.
-Don
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dlewis6767 <dlewis6767 at austin.rr.com>
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