[time-nuts] ideas so far for first GPS, NTP project

J. L. Trantham jltran at att.net
Sat Aug 18 21:23:29 EDT 2012


Frank,

At the prices I see on theBay for a 5087A, I would definitely try the video
distribution amp first.  There have been several solutions discussed on the
list.

The 5087A option I think you want is 033, one 10 MHz input, twelve 10 MHz
outputs.

The 5087A comes in several flavors.  The ones with the LED lights on the
front are newer.  The incandescent lamp units are older.  They were designed
to distribute 10 MHz, 5 MHZ, 1 MHz or 100 kHz with 10 MHz, 5 MHz, 1 MHz or
100 kHz input and just about any combination or permutation of those that
you could imagine.  The manual is available on the net
(http://www.ko4bb.com/Manuals/HP_Agilent/HP_5087A_Distribution_Amplifier_Ser
vice_Manual.pdf) and should answer your questions.

If you search 'GPS Timing Antenna' on theBay, you will see lots of
possibilities.  Someone on the list was offering new antennas at a good
price several months ago and may still have some available.

I use one like this (theBay item 270881742870) and it works well in NW
Florida under some trees.  I could get better performance if I had it up
higher but it serves my purposes.  There are also ones with higher gain out
there as well, up to about 40 dB IIRC.

Good luck.

Joe

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Frank Hughes
Sent: Saturday, August 18, 2012 7:53 PM
To: time-nuts at febo.com
Subject: [time-nuts] ideas so far for first GPS, NTP project


Hi,
Thanks for all the great tips and advice!
Quite a bit to absorb, but that is the fun part.

Probably not going to spend much more time trying to fix the 3336C OCXO, but
I will take it apart and check some basic things. 
The regulator is OK @ 14.1VDC, and the large metal BNC<->BNC jumper is
installed properly on the back panel. 
So it is going to be a bad crystal or other flaky discrete component causing
the 6Mhz output. 

The Jackson labs Fury sounds good to me, will save time for other 
phases of the project to provision the core as plug-n-play.

I have a Grass Valley 8X6 Video DA that I'll try first for 10Mhz
distribution. 
If the S/N ratio is too high, I'll try something else. 

(HP 5087A is "Plan-B", many on EB, but it is difficult for me to determine
which options/boards 
the vendors have in them - I'm not sure what to ask for) 

I would appreciate suggestions for an antenna - there are many on EB w/ "N"
connectors. 
I understand about the importance of placement and altitude, plenty of room
here, 
and I have quite a bit of left-over LMR-400 and LMR-600-DB, so loss won't be
a problem.

As for the NTP, I had hoped for a 1 or 2 RU server (Symmetricom/Datum), just
to make it simple to target my Linux, Mac clients @ a small cool running
platform I can leave on 24x7. 

All my Ubuntu and Fedora boxes are on old, hot, power hog platforms, and
thus, I don't run them 24x7. I'll ask the kids @ work about the newer,
energy efficient platforms I can run UBUNTU on.

They recently introduced me to ORACLE VirtualBox, now I have an XP running
in Ubuntu for things that just must have windoze. 
The only problem is getting the VirtualBox XP COM port to find and use the
Ubuntu serial card.

73
Frank
KJ4OLL
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