[Elecraft] Digital Mode Interface for the KX3 for WSJT modes

Don Wilhelm w3fpr at embarqmail.com
Fri Jul 13 20:42:09 EDT 2012


Sorry Bob,

I did not mean to ignore your initial offerings, but there were others 
chiming in with information that simply would not work, and assumptions 
that the KXUSB cable could provide PTT via RTS or DTR.
The folks at Elecraft support have also been asked questions about RTS 
or DTR PTT with the K3USB cable, and it is just not possible.

I was trying to provide the information requested - not by you, but by 
others who initiated emails based on your i\original question.

73,
Don W3FPR

On 7/13/2012 8:24 PM, Bob Cunnings wrote:
> Yes, I *know* that the KXSER serial cable carries only wires for TXD and RXD.
>
> That's why I said that the KXSER cable would run between the KX3 and
> the interface box.
>
> As the original message stated, a *full* serial port would run from
> the computer to the interface box, where PTT and CW would be broken
> out for connection to the KX3 independently of the serial line to the
> KX3 (which could be a KXSER).
>
> 73,
>
> Bob NW8L
>
>
>
> What is missing is that the KXSER serial cable carries only wires for
> TXD and RXD.
> Furthermore, the backshell is molded, so you cannot open it and add the
> wires.
>
> To use PTT from RTS or DTE, you would have to use a regular serial cable
> to your interface box, and then provide an outlet from that box to plug
> the KXSER cable into, and route the TXD and RXD signals on to the KX3.
>
> If one chooses to use the KXUSB cable, you would need 2 ports to use PTT
> from RTS or DTR.- one having the RTS or DTR signals and the other being
> a port associated with the USB to serial chip.
>
> 73,
> Don W3FPR
>
> On 7/13/2012 11:52 AM, Bob Cunnings wrote:
>> I don't understand this response. Why would he need to use 2 serial
>> ports or Y adapters? He states that a full serial port will run from
>> computer to interface box, where the serial signals will be broken out
>> as required for PTT and CW. Presumably the KXSER rs-232 cable could
>> run between interface box and the KX3 to convey RXD and TXD. What am I
>> missing?
>>
>> Bob NW8L
>>
>> Bill,
>>
>> You may want to re-think using the serial port on your interface.
>>
>> Most data mode applications like to use the same COM port for rig
>> control (OK, maybe just frequency display) as they use to activate DTR
>> or RTS for PTT.
>>
>> Given that the KX3 supplied cables only have RXD and TXD signals, using
>> the serial port to generate PTT requires that either you use 2 serial
>> ports (one may be the KX3 USB cable and the other can be a real port or
>> USB to Serial adapter), or provide a "Y" adapter to go to your
>> interface.  Use of the "Y" adapter precludes the use of the KX3 USB cable.
>>
>> There is nothing wrong with generating PTT from the audio stream, or
>> just using VOX in the KX3.
>>
>> 73,
>> Don W3FPR
>> On 7/13/2012 9:51 AM, Bill Conkling wrote:
>>> I am working on an interface in a box w/pcb.  Once you use a box, you can do
>>> anything.  I plan to have full serial port and two audio cables from
>>> computer.  Transformers in the audio chain and a 10K/1k attenuator in mic
>>> input to KX3.  I will split the serial port to provide proper connections
>>> for CAT, PTT, and CW as n1mm handles the K3.
>>>
>>> Whole thing in a 2.5X2.5X1 box.
>>>
>>> Big plans....
>>>
>>> ...bill nr4c
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