Thanks for all the comments and suggestions. I will continue to explore the possibility of an ultra-compact solution by just breaking out cables from a DB9 connector. However, in the interest of time, my first interface will use the RIGblaster Plug & Play unit from West Mountain Radio.
This compact unit provides a USB interface to the computer, plus completely isolated audio lines for input and output and isolated RTS (for PTT) and DTR (for true CW) keying from the computer. This interface also already includes a stereo jack for CI-V rig control, that appears to be directly compatible with the ACC1 jack on the KX3, so that is one less breakout connection I need to build! It also already has a separate jack for a speaker, so I can listen with headphones at the same time as the computer. This is especially handy when copying CW and still needing the audio to be fed to the computer so it can display the spectrum with a waterfall program such as Spectran. I have already ordered a couple inexpensive female DIN connectors from Digikey to connect with the output "ACC PLUG" line from the RIGblaster Plug & Play unit, and from there I will simply run a line to the KX3 Headphone Jack (for the audio out) and another shielded stereo cable to the KX3 4 pin microphone plug (for audio and PTT into the KX3). I will use the KX3 ACC2 jack to key my amplifier. I know there are others on this list who are interested in operating digital modes with an RTS line advance PTT keying capability, and I will provide photos and results as soon as I have everything completely assembled and tested. VY 73, Lance On 7/11/2012 4:48 PM, Lance Collister, W7GJ wrote: > I am still waiting for my KX3, but I imagine with over 600 of them out in the > field, SOMEBODY must have experimented with an interface for running WSJT > modes. I > will need to build up the custom interface cables as soon as my KX3 > eventually > arrives, and I won't have much time left to troubleshoot or re-do things. So > I > sure would appreciate any suggestions or guidance anyone with experience on > their > KX3 may be able to provide. I am HOPING there might be some way to simply > use > resistors to pad down the computer LINE OUT and isolate it enough to work > with the > KX3 MIC INPUT. > > I realize I will have to break out several of the serial port lines from the > computer DB9 and connect them to various jacks on the KX3. The TX (pin 3) > and RX > (pin 2) obviously must be connected to the ACC1 plug ring and tip, > respectively. > Do I just connect the sleeve of the ACC1 to both the SIGNAL GND (pin 5) AND > the > SHELL ground/cable shield? > > For the ACC2 plug, I am planning to use the RING to turn on my amplifier, and > the > TIP will be connected to RTS (pin 7) of the computer serial port. Wayne had > mentioned before that there should be a 2200 ohm resistor between the tip and > the > RTS line connection. I assume the sleeve of the ACC2 is connected to both > SIGNAL > GND (pin 5) AND the SHELL ground/cable shield? > > Of course, the KX3 HEADPHONE line will go directly into the computer LINE IN > - no > problem ;-) > > I am planning to connect the computer LINE OUT to the tip and sleeve of the > KX3 MIC > jack. However, in K9YC's interface manual, he suggests, putting a 4700 ohm > resistor in series with the tip, and putting a 470 ohm resistor from tip to > sleeve. Has anyone tried this yet on digital modes with the KX3? Does this > provide enough isolation and prevent hum? > > I see in the manual that a power cable with a 2.1-mm plug is supplied, so I > can use > that when I receive my KX3. > > I would greatly appreciate input from anyone who has already "broken trail" > on > building these KX3 interfaces ;-) MNI TNX and VY 73, Lance > -- Lance Collister, W7GJ (ex WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8, E51SIX, 3D2LR, 5W0GJ) P.O. Box 73 Frenchtown, MT 59834-0073 USA TEL: (406) 626-5728 QTH: DN27ub URL: http://www.bigskyspaces.com/w7gj Windows Messenger: [email protected] Skype: lanceW7GJ 2m DXCC #11/6m DXCC #815 Interested in 6m EME? Ask me about subscribing to the Magic Band EME email group, or just fill in the request box at the bottom of my web page (above)! ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
