[time-nuts] Z3815A

Murray Greenman Murray.Greenman at rakon.com
Thu Jun 10 19:24:23 UTC 2010


The Agilent Z3815A is a very nice unit, and fairly easy to get going.
The main problem is software, which we had to specially write, although
some versions of Ulrich's Z38XX work with it quite well. (The problem is
subtle differences in the SCPI syntax).

Yes, the backplane carries all the required signals except the serial
comms. Use 2.54mm spaced header pins to connect. For power, use a little
Veroboard with headers on. The DC supply connects to pins A54 to A58 (B)
and A59 to A63 (A). Polarity is unimportant, and it operates from
regulated 20 to 56V. A 24V 2A switch-mode plug pack will do the job.
This supply is isolated from the rest of the unit.

There are other outputs on the backplane, which I will leave you to
find! They include 19.6608MHz, 4.096MHz and 1.544Mhz.

The coaxial block consists of three independently buffered 10MHz sine
outputs at +13dBm (B1 to B3). The GPS antenna (5V active) connects to
A4. I've never had any success finding matching connectors at a sensible
price, and so simply solder the antenna cable and 10MHz outputs to the
back of the board. This connector is not soldered in, but simply held by
its insert barbs. You can't prize it out as a unit, but I'm told that if
you break up the plastic you can remove the inserts one at a time,
although I've not tried it.

The serial comms is wired with the wrong connector sense, so it's best
to make a dedicated cable, or use a Null Modem cable with a DB9 M-M
adaptor at one end. It doesn't talk unless spoken to, and uses
9600-N-8-1, SCPI protocol.

If you have one of the earlier Z3815A units, you will find the superb HP
E1938A 10MHz reference oscillator inside. There were manufacturing
problems with these units, I understand, and later ones (like mine) have
a Milliren 260 series 5MHz DOCXO (with excellent specs) on a daughter
board made by Symmetricom.

There is a full (unofficial) manual and software available on CD for the
Z3815A - write to kscally at bytecan.com.au. The manual lists all known
commands, and also covers the Korean clone of the Z3815A, which is
electrically and firmware different but externally identical. Software
includes a monitor program with multiple windows and a rather cool retro
and very realistic Nixie Clock.

Murray Greenman


Message: 4
Date: Thu, 10 Jun 2010 09:41:00 +0200
From: Magnus Danielson <magnus at rubidium.dyndns.org>
Subject: [time-nuts] HP Z3815A hookup
To: Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Message-ID: <4C10970C.10204 at rubidium.dyndns.org>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed


I just got a HP Z3815A but it seems like it is a bit of a challenge to 
hook it up. I see one large connector for some bus-structure, but don't 
know the pinning. There is also an 8 coax connector, where I suspect the

antenna, 10 MHz, PPS and other generated frequencies pop out. The RS-232

on the front is obvious.

I know there is a few SMBs inside, but it would be nice to get some 
practical hints from people playing with them before.

Yes, the hockey-puck is there.


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