[time-nuts] Buffering the 1pps output from a Z3801A
Jeff Mock
jeff at mock.com
Wed Mar 26 13:19:53 EDT 2008
That's a cool box, but I took a more quick and dirty approach that has
served me well. There's a TTL level PPS inside the box, if I remember
correctly the part has quite a lot of drive and is fine for driving a
50-ohm cable. I needed a proper UTC PPS signal for a radio astronomy
project and I made the following mod to my z3801a:
solder a 50-ohm resistor to the TTL PPS signal inside the Z3801A.
Use a nibbler tool to widen a cooling hole enough for a piece of
rg-58.
Zip tie a short piece of rg-58 coax into the hole in the side
of the box. I have a female connector dangling outside the box.
Wire the coax to ground and the 50-ohm resistor of the TTL drive.
This has served me well for many years and driven a variety
of spectrometers. The signal looks great on a scope when terminated
to 50-ohms, but it is a bit of a quick and dirty solution that might
not be appealing to some.
I can't tell you which chip/pin is the PPS signal, it was several years
ago. I'll remove the lid and tell you the proper pin if you take this
approach.
jeff
John Franke wrote:
> See; http://www.realhamradio.com/sidecar.htm
>
> John WA4WDL
>
> ----- Original Message -----
> From: "Peter Vince" <pvince at theiet.org>
> To: <time-nuts at febo.com>
> Sent: Wednesday, March 26, 2008 9:29 AM
> Subject: [time-nuts] Buffering the 1pps output from a Z3801A
>
>
>> 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?
>>
>> Thanks,
>>
>> Peter Vince (London, England)
>>
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