The KUSB cable used with the K3, as well as several other USB-to-Serial cables that provide a DE-9 connector, include "modem control" signals (RTS and DTR, etc) as well as TxD and RxD. N1MM uses these lines, in addition to the K3's PTT KEY menu, to use one serial port (with USB) to assert PTT and key the radio as well as "CAT" communications (frequency polling and the like). See http://en.wikipedia.org/wiki/Rs232 for a description of the various modem control lines.
The KXUSB cable provided with the KX3 carries only three wires: TxData, RxData, and signal ground. The "modem control" signals are not present in this converter. The KX3 does not provide a "PTT KEY" menu item because there are no DTR or RTS signals available. The KX3 does not use a "full" RS-232 cable, just the three wires needed for firmware load and serial communications other than RTS and DTR. The KX3 Utility uses the KX3's "KY" command to send CW characters. My understanding is that N1MM does not currently use the KY technique. N1MM's computer keying choices are (if I recall correctly), serial port keying (DTR for CW keying and RTS for PTT), and WinKey, a popular device provided by K1EL and integrated into a number of external keying controllers. I believe it is possible to use one USB to Serial Adapter serial port with the KX3, but you'll need to provide I little bit of wiring and a few devices on the DE-9 end of a "standard" USB to Serial adapter cable (such as the KUSB). The TxD, RxD, and Signal ground go to a 3.5mm plug that goes into KX3 ACC1. The DTR and RTS signals need to go to the KX3 key line and the ACC2 GPIO "PTT" connector, and some level shifting circuitry will be required. The common circuit for CW keying from a serial port, which pulls a positive voltage to ground using DTR is shown on AA5AU's web at http://www.aa5au.com/rttyinterface.html. For most radios, the RS-232 RTS line is used with a transistor switch to pull PTT down to ground. This might work through the KX3's microphone connector. But the KX3 owner's manual description of the ACC2 GPIO line says that you need to provide not more than 3V to use it for PTT. A series resistor may suffice, or perhaps a level shifter that transforms the 5 or 12V that your USB to serial adapter provides on RTS to the at-most 3V that the KX3 ACC2 GPIO input will tolerate. There are advantages to a WinKey. I've used this device (embedded in controllers) for some time. See http://k1el.tripod.com/products.html and http://k1el.tripod.com/WhatisWK.html Sometimes computer-generated CW timing can stutter depending on the operating system's dispatching priorities. Occasionally in mid-contest I've had activity from other processes disturb the timing of CW keying. My computer might start a nightly virus scan, or backup, or maybe one of several products (Microsoft, Java, Adobe) wants to check for updates, and I forget to turn this stuff off before a contest. N1MM itself might be very busy updating the band map, dealing with lots of internet traffic from spotting networks, perhaps looking up call signs in a large "super check partial" database, and I've had some CW stutter. This depends on the computer speed and size of the log and is very difficult to test ahead of the contest. Contest logging programs are amazingly complex pieces of software, and it sometimes makes sense to offload some of the critical timing tasks (sending good Morse code at speed) onto a dedicated device. A Winkey is inexpensive and quite useful. But it's yet another box to deal with... 73 de Dick, K6KR -----Original Message----- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of John Lawrence via Elecraft Sent: Sunday, May 11, 2014 6:54 AM To: elecraft@mailman.qth.net Subject: [Elecraft] Keying oand sending CW on KX3 with N1MM I tried to get the KX3 to work with the latest rev level of N1MM and configured it per the instructions for one cable connection using just the USB to serial cable supplied to go between the radio and PC win7. The configuration talks ok at 38400bps with commands for changing bands, vfo frequency and mode but I get an error message saying no CW port has been selected. I'm running on COM 3. In reading through the help manual I some radios require cw keying via a separate keying line into the KX3 using the serial commands set. Anyone been through this with the KX3 and figured out how to run with only the USB to serial cable? Thanks John, W1QS ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to d...@elecraft.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
