[time-nuts] Buffering the 1pps output from a Z3801A

[Magnus Danielson]

From: Peter Vince <pvince at theiet.org>
Subject: [time-nuts] Buffering the 1pps output from a Z3801A
Date: Wed, 26 Mar 2008 13:29:36 +0000
Message-ID: <v04210100c40fff3e85d9@[10.0.0.3]>

> Bruce, et al,
> 
> 	The 1pps output of an HP Z3801A and Trimble Thunderbolt is 
> only available (as far as I know) as a balanced ECL signal on the 
> 25-pin connector, with dire warnings in the manuals about not 
> earthing either side of the ECL signals.  Would you be able to advise 
> on a simple buffer circuit that would allow me to drive the usual 
> unbalanced 50-ohm coax please?

Look at the side-car project for the PPS output. You can skip the NE555 if you
don't need the pulse-length thing. A single RS-485 receiver should do it.
Notice how both the positive and negativ signal is DC terminated as this is
what you need for a PPS signal.

Come to think of it, I need to cook up something similar for my Z3801A too.
Another project in the heap of projects. Hurray!

There are times when real ECL outputs are nice too. If I had any suitable
ECL buffers lying around I would provide ECL output buffers too.

Cheers,
Magnus