[1000mp] RS232 port repair

[Zoli Pitman HA1AG]

Hi Mac, 

I suggest to use an optical isolator pair in your cat line. There are specific isolator IC's for this purpose. 

I use two optocouplers,  where the rig tx side is fed by it's internal 13V (available on backplane connectors), and I instruct my pc to pull up DTR to supply the PC TX side. It is build on piece of perfboard and sits in the rig. 

73, zoli ha1ag




----- Original Message ----
From: J. C. Mc Laughlin <jcm at power-net.net>
To: 1000MP Dec2001 <1000mp at mailman.qth.net>
Sent: Saturday, April 4, 2009 10:31:46 PM
Subject: [1000mp] RS232 port repair

Dear Group:

    A weak link with the FT1000 Mk V (and probably all of the other members 
of the family) is the CAT port.  The chip used is fragile.

    The chip appears to be an Analog ADM232LJR for which a MAX232CWE is 
supposedly a pin-for-pin substitute.  Improvements have taken place in such 
chips.  I propose to replace my defective chip with a ADM202EARWZ (the Z 
just indicates low Pb).  The ADM202EARWZ appears to be a pin-for-pin 
replacement, a chip with considerable resistance to ESD, and a chip with 
attention paid to EMC.

    What experience have group members had with more rugged substitutes to 
the original RS232 chip?

    Today, one would design using an optically isolated chip, but I did not 
find one that is a direct replacement.

    73,    Mac    N8TT