[time-nuts] Re: Issue with my 3816a

[Chris Quayle]

> My HP 3816A is no longer working properly. I can communicate with it through
> the serial interface, however it never acquires any satellites. It
> occasionally shows satellites in the process of acquisition, but for the
> most part there are no satellites acquired in Lady Heather or GPSCON.  I
> suspect the GPS card, as I don't get any response when I remove it and try
> to connect to the software in a standalone mode. I know that I can purchase
> a new GPS card, however before I spend $200 on a new card, I'd like to know
> it will fix my issue as the card is non-returnable. If someone has an extra
> GPS card for this unit that they could lend me, that would be great
> (alternatively, I'd be happy to send my 3816A if you can test with your
> card). I have working Motorola cards from TAPR that fit into the 3816, but
> they do not solve the problem. The 3816A does pass all the self-tests.
> 
> Regards,
> 
> Mitch 

I ran a Z3816 for around a decade, but one fault along the
way was the power supply. They tend to run quite hot and there
is a input series resistor used to drop some line volts
right next to the input cap. Similar fault, but fixed by
replacing all the electrolytics. Can be confirmed via a scope
on the output rails, which should show low ripple normally.

Eventually retired it when the OCXO ran out of control loop
range, and would no longer lock to gps...

Regards,

Chris