[TenTec] hp Z3801A Interface Unit

[Eric F. Richards]

At 03:23 PM 6/4/2003 -1000, you wrote:
>Hi,
>
>For those of you as I am,  perhaps unable,  for whatever
>reasons,  to do close in,  fine wire,  tiny circuit board
>component mod type stuff,  I have found the following
>component.  Seems to be just what is needed to
>interface the 25 pin RS-422 connector on the back
>of the hp GPS unit to the RS-232 circuit of our PC's.
>I will also need DB-25 to DB-9 adaptors to get into
>my PC COM port.
>
>Have a look to see if I am correct.  Would save me,  at
>least,  a huge amount of effort (coaching my wife how to
>do some circuit mods, tiny wire job,  etc.);  would rather
>not!  See:
>
>http://www.telebyteusa.com/catalog/products/260.htm
>
>73,  Jim  KH7M

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.  Now the manual says that it derives its power from the RS232
side, and if that is so, you're okay.

It is important to note that whether you do the internal jumpering
as I did for RS232 or you leave it for RS422, the only "valid" signals
are TxD, RxD and Gnd.  The rest are NOT compliant signals -- they're
various clock signals and voltages.

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.

I did the internal jumpering without problems, and I'm a Certified Klutz
with SMD.  However that board is very sparse so there's lots of room to
make mistakes.  The real scary part was getting all the boards out to get
to the bottom of the last one.

Eric

(P.S. Jim, can you breadboard something externally?  I know some of the
sites linked from Buylegacy.com have schematics of a converter, and the
price of that thing is aufully steep.)

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