K3: RS-232 cable

[Julian, G4ILO]

The manual says: "Do not use a cable wired for use with an Elecraft K2
or K2/100 transceiver or accessories. They may be wired differently."

As far as I remember, the K2 serial cable was just a standard 3 wire
cable, to which I added a transistor switch driven by DTR or RTS
(can't remember which) for CW keying. Even with this addition, I can't
see why I couldn't use it with the K3. What is the point that I am
missing?
--
Julian, G4ILO K2 s/n: 392  K3 s/n: ???
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[JT Croteau]

On 10/11/07, Julian G4ILO <[hidden email]> wrote:
> As far as I remember, the K2 serial cable was just a standard 3 wire
> cable,

Yes, but the K3 is wired differently.

On the K3, pin 2 is RXD and pin 3 is TXD
On the K2, pin 2 is TXD and pin 3 is RXD

Also, some K2 serial cables use additional pins for things like XV and
KAT100 control.

--
JT Croteau, N1ESE - Manchester, NH (FN42gx)
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[Mark Bayern]

>>"As far as I remember, the K2 serial cable was just a standard 3 wire
cable, ... What is the point that I am missing?

If your K2 cable had only three wires, signal ground, send data and
receive data, there is no _major_ difference.  Just the 'normal' pin
2/3 confusion. Some K2 cables include the auxbus signals that are used
for the KAT100 and (I guess) the XV series.


Mark AD5SS
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[JT Croteau]

On 10/11/07, Mark Bayern <[hidden email]> wrote:
> If your K2 cable had only three wires, signal ground, send data and
> receive data, there is no _major_ difference.

Big difference.  Send Data and Receive Data on the K3 are opposite
that of the K2.

(According to the K3 web manual)

--
JT Croteau, N1ESE - Manchester, NH (FN42gx)
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[Julian, G4ILO]

Ah. I never realised that the pins were reversed. What a pity you
can't just swap the cable between radios.

--
Julian, G4ILO K2 s/n: 392  K3 s/n: ???
G4ILO's Shack: www.g4ilo.com
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On 10/11/07, JT Croteau <[hidden email]> wrote:
>
> Yes, but the K3 is wired differently.
>
> On the K3, pin 2 is RXD and pin 3 is TXD
> On the K2, pin 2 is TXD and pin 3 is RXD
>
> Also, some K2 serial cables use additional pins for things like XV and
> KAT100 control.
>
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[Thom LaCosta]

On Thu, 11 Oct 2007, JT Croteau wrote:

> On 10/11/07, Julian G4ILO <[hidden email]> wrote:
>> As far as I remember, the K2 serial cable was just a standard 3 wire
>> cable,
>
> Yes, but the K3 is wired differently.

I remember all sorts of cautions about NOT using a standard rs-232(serial) cable
with the K2...

Does it noow mean that in addition to not using a k2 cable for the k3, that we
can use a standard serial cable with the K3?

73-thom-k3hrn
Blessed be standards, as they shall change with time.

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[JT Croteau]

On 10/11/07, Thom LaCosta <[hidden email]> wrote:
> Does it noow mean that in addition to not using a k2 cable for the k3, that we
> can use a standard serial cable with the K3?

Yes, as long as it is a straight through cable.  From the manual:

"A straight-through, 9-pin RS232 cable is required between the K3 and
the computer's RS232 port or USB-to-RS232 adapter. Use a high-quality,
fully shielded cable."

(Page 18, Web version of K3 manual)

--
JT Croteau, N1ESE - Manchester, NH (FN42gx)
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[Thom LaCosta]

On Thu, 11 Oct 2007, JT Croteau wrote:

> On 10/11/07, Thom LaCosta <[hidden email]> wrote:
>> Does it noow mean that in addition to not using a k2 cable for the k3, that we
>> can use a standard serial cable with the K3?

Thanks....I guess I better find my old, huge and obnoxiously colored
RTFM Sign and put it back up on the wall.

73 - k3hrn
Thom,EIEIO
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[Mark Bayern]

> Big difference.  Send Data and Receive Data on the K3 are opposite
> that of the K2.

Big difference? I said 'no _major_ difference'.  Crossing pins 2&3
will not destroy anything. Since the beginning of time ... well ... at
least since the beginning of DTE and DCE RS-232 devices, pins 2&3 have
been a problem. Using the wrong cable on a K2 will destroy things.

We gotta keep the priorities straight. 1--Don't let the smoke out of
the chips. 2--Make it work.

Mark  AD5SS
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[Julian, G4ILO]

Personally I'd call that a major difference, too. Not as major as
blowing the radio up, granted, but major enough for me to think
something was wrong other than the pins were the other way round.
Somehow I never imagined Elecraft would create incompatible interfaces
for its two radios.

Anyway, thanks for the answer. All I have to do now is remember it
when the K3 actually gets here and I try connecting it to the
computer. :)

--
Julian, G4ILO K2 s/n: 392  K3 s/n: ???
G4ILO's Shack: www.g4ilo.com
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On 10/11/07, Mark Bayern <[hidden email]> wrote:
> > Big difference.  Send Data and Receive Data on the K3 are opposite
> > that of the K2.
>
> Big difference? I said 'no _major_ difference'.  Crossing pins 2&3
> will not destroy anything. Since the beginning of time ... well ... at
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[Ed Muns, W0YK]

> Does it noow mean that in addition to not using a k2 cable
> for the k3, that we can use a standard serial cable with the K3?

Yes, a standard serial cable available at any computer outlet.  "Standard",
not "Null Modem".

73,
Ed - W0YK

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[Julian, G4ILO]

The downside being that ready made cables usually have molded-on
plugs, so you can't fit a keying circuit inside.

--
Julian, G4ILO K2 s/n: 392  K3 s/n: ???
G4ILO's Shack: www.g4ilo.com
Ham-Directory: www.ham-directory.com


On 10/11/07, Ed Muns <[hidden email]> wrote:
> > Does it noow mean that in addition to not using a k2 cable
> > for the k3, that we can use a standard serial cable with the K3?
>
> Yes, a standard serial cable available at any computer outlet.  "Standard",
> not "Null Modem".
>
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[JT Croteau]

On 10/11/07, Julian G4ILO <[hidden email]> wrote:
> The downside being that ready made cables usually have molded-on
> plugs, so you can't fit a keying circuit inside.

You don't need to.  The K3 is wired for DTS and RTS keying, see page
18 of the web manual:

"PTT and Keying: The DTR and RTS signals are not used as RS232
hardware handshaking lines. Instead, the K3 can be configured to use
either of these signals as PTT IN or KEY IN via the CONFIG:PTT-KEY
menu entry. No external level translation is required, since these are
RS232- compatible inputs. The default for both signals is inactive
(unused). Refer to your software
documentation to see if PTT or keying via RS232 lines is available."

--
JT Croteau, N1ESE - Manchester, NH (FN42gx)
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[JT Croteau]

On 10/11/07, JT Croteau <[hidden email]> wrote:
> You don't need to.  The K3 is wired for DTS and RTS keying, see page
> 18 of the web manual:

I should have said DTR not DTS, my bad.

--
JT Croteau, N1ESE - Manchester, NH (FN42gx)
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[Ed Muns, W0YK]

> The downside being that ready made cables usually have
> molded-on plugs, so you can't fit a keying circuit inside.

No, there is no need for a "keying circuit" or level shifter with the K3.
It is RS232 levels on both the computer and K3 ends.  Furthermore, the
CONFIG menu lets you choose which pins (RS232 signals) are used for CW
keying and/or PTT.

73,
Ed - W0YK

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[Julian, G4ILO]

You're right. It's a lot to take in. I read that paragraph the first
time round but it didn't sink in that it was referring to the PTT and
key lines, not the serial data.

It's not enough just to RTFM, you also have to U(nderstand)TFM.
Getting old, I guess. :(

--
Julian, G4ILO K2 s/n: 392  K3 s/n: ???
G4ILO's Shack: www.g4ilo.com
Ham-Directory: www.ham-directory.com


On 10/11/07, Ed Muns <[hidden email]> wrote:

> > The downside being that ready made cables usually have
> > molded-on plugs, so you can't fit a keying circuit inside.
>
> No, there is no need for a "keying circuit" or level shifter with the K3.
> It is RS232 levels on both the computer and K3 ends.  Furthermore, the
> CONFIG menu lets you choose which pins (RS232 signals) are used for CW
> keying and/or PTT.
>
> 73,
> Ed - W0YK
>
>

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[Thom LaCosta]

On Thu, 11 Oct 2007, Julian G4ILO wrote:

> You're right. It's a lot to take in. I read that paragraph the first
> time round but it didn't sink in that it was referring to the PTT and
> key lines, not the serial data.
>
> It's not enough just to RTFM, you also have to U(nderstand)TFM.
> Getting old, I guess. :(

It's good that Elecraft is supplying a printed manual since
SOODBWP
(Some Old Operators Do Better With Print)

73-k3hrn
Thom,EIEIO
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[Greg - AB7R]

Yes,  You can use a standard serial cable with the K3.

-------------------------
73,
Greg - AB7R
Whidbey Island WA
NA-065
K3#0009

On Thu Oct 11  8:47 , Thom LaCosta  sent:

>On Thu, 11 Oct 2007, JT Croteau wrote:
>
>> On 10/11/07, Julian G4ILO [hidden email]> wrote:
>>> As far as I remember, the K2 serial cable was just a standard 3 wire
>>> cable,
>>
>> Yes, but the K3 is wired differently.
>
>I remember all sorts of cautions about NOT using a standard rs-232(serial) cable
>with the K2...
>
>Does it noow mean that in addition to not using a k2 cable for the k3, that we
>can use a standard serial cable with the K3?
>
>73-thom-k3hrn
>Blessed be standards, as they shall change with time.
>
>www.baltimorehon.com/                    Home of the Baltimore Lexicon
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[Don Wilhelm-4]

JT and all,

Pins 2 and 3 are not swapped on the K2 either.  The problem is that the
K2 used the nomenclature differently than the K3.   The K2 used 'TXD' to
denote the line *it* was sending on and 'RXD' to denote the line it was
receiving on.  The K3 apparently uses the opposite nomenclature and
labels *its* data *output* line 'RXD (that is correct for a DCE device).
Pin 2 is the data from the DTE (K2 or K3) to the DCE (PC) and is
normally termed RXD.  Pin 3 is data from the DCE (PC) to the terminal
device (DTE) and is normally labeled TXD.

This has been a source of confusion when working with DCE devices for as
long as I can recall.

So *if* only RXD and TXD with Signal Ground are needed for the
application, yes, the K2 cable (computer end, not KAT100 or XV end) will
work just fine, but why not pick up a standard serial cable and take
advantage of the PTT/Keying circuits built into the K2 - that will work
with no external keying devices.

73,
Don W3FPR

JT Croteau wrote:

> On 10/11/07, Julian G4ILO <[hidden email]> wrote:
>  
>> As far as I remember, the K2 serial cable was just a standard 3 wire
>> cable,
>>    
>
> Yes, but the K3 is wired differently.
>
> On the K3, pin 2 is RXD and pin 3 is TXD
> On the K2, pin 2 is TXD and pin 3 is RXD
>
> Also, some K2 serial cables use additional pins for things like XV and
> KAT100 control.
>
>  

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[Don Wilhelm-4]

I had a typo in the last part of my previous note.  That should have
been *K3*.
Do *not* use a standard serial cable with the K2!

Sorry,
Don W3FPR

Don Wilhelm wrote:
>
> So *if* only RXD and TXD with Signal Ground are needed for the
> application, yes, the K2 cable (computer end, not KAT100 or XV end)
> will work just fine, but why not pick up a standard serial cable and
> take advantage of the PTT/Keying circuits built into the *K2* - that
> will work with no external keying devices.
>
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