K3 serial cable

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K3 serial cable

Paul-285


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,

Paul




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Re: K3 serial cable

Don Wilhelm-4
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

[hidden email] 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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RE: 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: [hidden email]
[mailto:[hidden email]] On Behalf Of Don Wilhelm
Sent: Friday, January 11, 2008 9:35 AM
To: [hidden email]
Cc: [hidden email]
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

[hidden email] 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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