[time-nuts] 10 MHz OCXO recommendations
EWKehren at aol.com
EWKehren at aol.com
Tue Nov 11 07:00:14 EST 2014
Joe
It is not clear to me what your goal is. Simplicity, cost or performance. A
PLL based on 1 pps is not optimum.
I call this approach GPSPLL versus GPSDO. Thanks to work done by Karen in
Moscow I found out that you can program a $14 ublox M7 to frequencies above
1 KHz. If you use 200 KHz for 5 MHz XO and 400 KHz for 10 MHz you can make
a GPS PLL with one 390, one 86 and an op amp. If the XO output is sine wave
you have to add a Schmitt Trigger. I recommend Wenzel, AC14 or SN75176. I
prefer 75176 it is 8 pin DIL.
I do have a board layout if interested. Our Australian team members will
introduce it to the HAM community. Not exactly a time nut product.
We have done a GPSPLL using a M7 at 1 KHz and tests show better than 1 E-10
at 1 second after 10 seconds GPS takes over it gets better following GPS
performance. I have a few boards and op amps left over if interested contact
me off list.
Bert Kehren
In a message dated 11/11/2014 1:05:49 A.M. Eastern Standard Time,
jgray at zianet.com writes:
> You can run at 400 KHz by dividing by 5/5 and 4/9.
True. Either will work.
> You said "0.2ppm stability". What do you need for accuracy and/or how
are you going to calibrate your setup?
I will initially calibrate the OXCO against my HP GPSDO. Idealy, it will
only need checking against the GPSDO once a year. Is that asking too much
for it to be stable over that length of time?
I could simply look up the specs for the various models that I find on
ebay. However, I know that a lot of the stuff that is sold has been through
the mill and may not meet spec any more. Thus my request for
recommendations for models that someone here has actually purchased and
tested.
Joe Gray
W5JG
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