[TenTec] hp Z3801A Interface Unit

[Eric F. Richards]

Hi, Jim,

At 06:03 PM 6/4/2003 -1000, you wrote:
>Aloha Eric,
>
>You wrote,  in part:
>
> > Hi, Jim,
> >
> > I took a look at the online manual for it and it will probably
> > do the job.  However, you aren't out of the woods just
> > yet because on the Z3801 side you'll have to block all
> > signals but TxD, RxD and Gnd.
>
> > A simple breakout box to pass 2, 3, and 7 (for RS232)
> > would be okay.
> > Note also that your wire has to be null-modem -- the
> > clock is DTE -- to connect to your computer.
>
> > (P.S. Jim, can you breadboard something externally? )
>
>Oh my!  Eric,  this just becomes more and more silly!
>Yes,  I can work pretty well with external perf board;
>have done that a bit already since my vision went South, hi.
>
>I have no idea what you mean about "block all signals but...";
>and what is this about "wire has to be null-modem -- the
>clock is DTE -- to connect to your computer."

Well, on the back of the Z3801A there is a 25 pin connector.
In RS232 or RS422, those pins have specific assignments, some
of which are useful for communicating to a modem, some of them
are used for synchronous communication, etc.  In any case, they
have signals on them or expect signals on them.

On the Z3801, instead of conforming to that standard, HP stuck
other signals on them, and plugging in a normal jumper cable
could possibly do damage to the HP, your computer or both.

Now, the signals I referred to -- TxD, RxD and Gnd -- are all
that your computer needs to talk to the HP.  On a 25 pin connector,
those pins are 2, 3 and 7.

Now, you can buy a radio shack breakout box that will let you just
connect those wires through and leave the others disconnected.  What
you would do then is plug the breakout box into the HP clock, then
plug the RS422 to RS232 converter into that breakout box, then plug
the cable that goes into your PC into *that*.

That converter you mentioned has a switch for handling null-modem
connections, so you would set it appropriately (if one position
doesn't work, try the other!) and you'd be off and running.

Now if you have a local computer nerd that can help you with these
things, you might be able to get set up without dealing with the
breakout box.  After all, this part of the clock is just computer
communications, no RF involved.



>I am starting to believe I am in over my head;  but,  I have
>already put the hp Z3801A on order!

You may be able to get away without ever connecting it to a
computer at all, but it will take some time to find its new
location -- like a day or so.  A front-panel LED will tell
you when the clock is locked on.


>Is there some less costly solution for me?  I mean something
>I can do that won't require my XYL getting involved?  She
>is a great gal,  but at 66 already has her hands full trying
>to keep order at the hospital, hi!  She is more than willing
>to help (already has done a bit of a mod inside the RX-340
>for me),  but it is a chore for both of us.  And, I am older than
>that,  hi!

Well, like I said you might be able to get away without having
it talk to a computer at all.  Might be worth just letting it run
for a few days to see if it locks up.  You also might try the local
computer shop.

You'll get a manual with the clock.  Page 2-7 has a table of the
connector pinouts.  If you have a computer store near you and they're
helpful, they might be able to get you going with a little less effort.


>With large enough parts and wires,  I can do it,  if I can see
>them!

Are DIPs and thru-hole components big enough? The PDF (found on
www.realhhamradio.com) has converters.

http://www.realhamradio.com/k8cu%20gps%20interface%20and%20power%20supply.pdf

But your commercial converter will do the job if set up as I described
way back at the beginning of this message!

Good luck!

Eric

--
Eric F. Richards
efricha at dimensional.com
"The weird part is that I can feel productive even when I'm doomed."
  - Dilbert