[Elecraft] K3 serial cable

[Dick Dievendorff]

TX Data, RX Data, and Signal Ground are the only lines required for firmware
loading.

However you may find it useful to also wire DTR and RTS so that computer
logging / keying programs can use these leads for PTT and CW keying.

Details of which pins are what are in the KIO3 section of the K3 Owner's
manual (currently page 18).

I generally would recommend a shielded "straight through" 9-pin M-F DB-9
serial cable.  All 9 pins wired so that each pin on one end is wired to the
same pin on the other.

Avoid "crossover" or "null modem" cables.

73 de Dick, K6KR


-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Don Wilhelm
Sent: Friday, January 11, 2008 9:35 AM
To: Paul at N4LCD.com
Cc: elecraft at mailman.qth.net
Subject: Re: [Elecraft] K3 serial cable

Paul,

Yes, but... it needs a DE9 male on one end, a DE9 female on the other.  
The computer port has a male jack and the K2 has a female jack.  Look at 
the cable construction information in the KIO2 or KPA100 manuals.

You have the pins correct, but the wire you have will not likely provide 
enough isolation - If you do not have the proper 4 conductor shielded 
cable, I would suggest that you use CAT-3 or CAT5 wire which has twisted 
pairs (you need two twisted pairs) to take advantage of the signal 
isolation the twisted pairs will provide - connect one side of a pair to 
pins 3, and the other side of the same pair to pin 5 - a second pair 
connects one side to pin 2, and that pair's return is also connected to 
pin 5.  If the CAT5 or CAT3 cable is shielded, I would connect the drain 
wire to pin 1 at the K2 end only so it acts like a faraday shield - 
caution: pin 1 at the computer end is NOT the shield connection (it is 
carrier detect), if you want to connect a shield at both ends, connect 
it to the DE9 shell at the computer end (see RS-232 pinout for DE9 
connectors)

73,
Don W3FPR

Paul at N4LCD.com wrote:
>
>
> So the K3 F/F DE-9 serial cable only needs TX, RX, and SG?
>
> Pins 2, 3, and 5 only...
>
> Straight through...
>
> I've got some cable with one twisted pair inside a foil shield with an 
> un-insulated ground wire (I believe it's called the drain) in there 
> too, and it contacts the foil shield full length.  Would that work?
>
> Should I slip some ferrites (which I already have) over the cable's 
> jacket before soldering the DE-9/F's on?
>
> 73,
>
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