[Elecraft] No serial connection between K3 and computer

[Vic Rosenthal 4X6GP/K2VCO]

If you tried with two computers and various cables, then the problem is 
likely in the K3.

What 'zapped' the directional coupler? If it was nearby lightning, then 
it is not unlikely that it could have damaged the serial chip in the 
KIO3. I don't know what kind of testing Elecraft did, but perhaps they 
didn't use a computer connection to do it. Also, static damage to a chip 
might not appear immediately.

I suggest calling or emailing Elecraft support.

On 5 Jan 2015 05:02, Rene Correa, K5JX wrote:
> Greetings.
>
> I am no longer able to control my K3 (SN 7845)with my Dell Optiplex 740,
> running Windows 7 or with my Dell Latitude D610, running Windows XP. The
> arrangement used to work (running 4800 baud), but not now. I am using
> the "real" serial port on each computer.
>
> I've tried two different "straight through" serial cables that have
> worked with the K3 and both Dells previously. Both cables show
> continuity on all nine wires. Today I used both cables to connect my AIM
> 4170C analyzer to the Optiplex and everything appeared to work properly.
> So, I think I've ruled out the serial cables. I have run the Optiplex's
> device manager ragged, checking and rechecking the COM1 port many times.
> I've tried updating the driver several times and have always gotten a
> message that the most current driver is installed. I've also always
> gotten a "the device is working properly" message.
>
> I have tried all sorts of baud rate combinations (less than, equal to
> and greater than 4800 baud) with the K3 and the Optiplex, always
> starting my experiments with the same baud rate for COM1 and the K3 and
> then either leaving the COM1 baud rate constant while varying the K3
> baud rate or leaving the K3 baud rate constant while varying the COM1
> baud rate. In every instance, all the K3 Utility gives me are scrolling
> messages that say, "Attempting to contact K3 on port COM1 at 38400
> bit/s", "Attempting to contact K3 on port COM1 at 19200 bit/s",
> "Attempting to contact K3 on port COM1 at 9600 bit/s", "Attempting to
> contact K3 on port COM1 at 4800 bit/s", etc.
>
> I've pulled the top cover off the K3 and measured the voltage on pin 8
> of U1 on the KIO3 board. I measured a little over -7 VDC, so that looks
> okay, as per KE7X's book.
>
> I sent the K3 to Elecraft a few months ago to fix a zapped toroid in the
> directional coupler. The computer control worked before the zap.
> Elecraft satisfactorily repaired the K3 and fully tested before it was
> returned to me. As far as I can tell, none of my settings were changed
> while the rig was at Elecraft. I've operated the K3 mobile, with no
> computer control and it has worked like a champ. However, a few days
> ago, when I connected it back up to Optiplex (and later the Latitude), I
> became aware of the serial port problem.
>
> I am at my (half) wit's end and have to believe I am overlooking
> something obvious. Can anyone please suggest what, if anything, to try
> next?
>
> Many thanks and 73.
>
> Rene K5JX

-- 
73,
Vic, 4X6GP/K2VCO
Rehovot, Israel
http://www.qsl.net/k2vco/