[time-nuts] new member with questions NTP, PRS, GPS, ocxo

J. L. Trantham jltran at att.net
Sat Aug 18 12:47:35 UTC 2012


I use a Trimble Thunderbolt that puts out 10 MHz and 1 PPS.  I also use a
Z3816A that also puts out 10 MHz and 1 PPS along with another frequency that
I can't remember right now.  Both can be monitored with their respective
software programs and a serial cable.  The Z3816A needs a null modem adapter
IIRC.  Both put out 5 VDC to power a GPS Antenna.  I use a 58536A Active
Splitter to feed the antenna to both units along with some 'spare' GPSDO's.

The TBolt requires +12 VDC, -12 VDC, and +5 VDC.  The Z3816A comes in at
least two variants, one requiring 120 VAC and the other something around 30
VDC.  I have seen mention that you can run it on 12 VDC if you change some
settings on the DIP switch S1 on the power board.  I have not tried that.

There is lots of useful information on the net and these lists/forums about
both units.

I distribute 10 MHz using some 5087A's with the 10 MHz cards installed.

A crystal oscillator for 10 MHz that puts out 6 MHz doesn't sound very
repairable.  Have you looked at the signal with a scope?  Is it something so
simple as major ripple/modulation from the power supply?

Good luck and hope this helps.


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Frank Hughes
Sent: Friday, August 17, 2012 8:12 PM
To: time-nuts at febo.com
Subject: [time-nuts] new member with questions NTP, PRS, GPS, ocxo

New guy here, seeking Oracular pronouncements for my time/frequency quest!

I recently acquired an HP 3336B, and subsequently converted it to a "C"
model, as all the HAM and related equipment here is 50 ohms.

The 3336 has "Option 004: High stability frequency reference". 
Operates at about 6Mhz....

I am trying to decide whether to fix the 3336 ocxo, or just use the other
working ocxo in the Agilent E8285A Spectrum Analyzer. OR It would really be
fun to provision some type of Primary Reference and accurate 10Mhz source,
and distribute the signal.

I found a bunch of them on ebay, but they are almost all in China....what is
going on here?

Anyone ever had a good buying experience for this type of equipent from

While decending through this particular worm-hole,  I realized that it would
be great to have 
my own NTP server via GPS too. 
Found a bunch of GPS receivers w/ Ethernet and NTP server features, but none
w/ ocxo, only vcxo and tcxo. 
Possibly it does not matter if the reference is the Stratum-1 GPS? 
Not sure what I am looking at here (obviously)

I only know a little about these topics, as where I work we have an
Agilent_5071A, paired with a 
Symmetricom GPS PRS system. 
But as we have moved out of the old TDM and ATM technologies, we no longer
need a Stratum-1 source, (and the 5071A has used up all it's Cesium anyway).
But it was fun and I learned many things.

So what I am trying to come up with now for home/shack is:
- An NTP server for our LAN 
- A very high quality 10Mhz source to distribute to all the HP and Agilent
equipment here.

I have read enough forums to become dizzy, and would be glad to buy an HP
Z3815A, or an HP Z3816A or an HP Z3801A or... I even found an HP 55300A, but
w/o the shelf it is useless, 
(100 edge connector pinouts to decipher and wire manually???)

Advice much appreciated!
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