Discussion in 'QRP Corner' started by MM3ENM, Jul 31, 2019.
Does anyone use a KX3 for data modes?
If you're using soundcard data modes, put the radio into "DATA A" mode. This sets a wide bandwidth and removes all filtering, compression and EQ from both the audio in and audio out lines. It also uses USB. See page 18 of the KX3 manual.
But don't feel you absolutely must leave things this way. If there's a strong signal near a weak one, sometimes you can improve the reception of the weak signal by eliminating the strong neighbor using the PBT knob, the same as you would in CW or any other mode, to set the width and position of the passband on the waterfall.
The KX3 "natively" supports PSK D (PSK31) and FSK D (RTTY), which can be used with paddles to generate the transmitted characters. Decoded characters show on the KX3's small screen area. If you connect the KX3 to a PC with a serial cable, you can use the KX3 Utility Program to use these same modes, with a larger screen and more macro buttons. This is a very simple program, compared to something like Fldigi, but there are no audio levels or external interfaces to set up if you use either of these "D" digital modes.
Also, if you have the PX3 panadapter, you can plug a USB keyboard into that and run PSK D or FSK D without connecting a PC. The lower portion of the PX3 can be set for text display, and this is considerably larger than the KX3's text display. Transmitted and received data are shown in different colors, but there is no support for carriage returns.
As mentioned above, "DATA A" is what you want for external digital mode software. You may be able to get this to work with just 3.5mm audio patch cables for the audio paths and a serial cable for rig control. The software will have to support VOX keying and you have to make sure your PC's "system" sounds are disabled.
You can use something like a SignaLink USB to provide a second sound card and a way to generate a PTT signal for the transceiver without requiring a second serial port. I believe the software has to be set for VOX, but the KX3 has to be set for PTT. The SignaLink does not provide for rig control or a CW KEY signal.
Other interfaces can provide a full solution, including an "audio card", a serial port for CAT and another serial port for PTT and CW KEY control signals. The Rig Expert TI-8 is one such interface, and the manufacturer offers cables designed for the KX3.
I'm using a SUCCI-R for digital modes on my KX3. This is a USB serial adapter which provides a "full" serial port with PTT and CW KEY signals, so I can use CWGet/CWType/TrueTTY. I'm using in-line isolation transformers on the PC audio cables, and I made a custom "Y" cable to route both audio and PTT to the KX3's TRRS mic jack.
Next time there is a RTTY contest, I plan to try some of these options.
Many thanks AG6QR and KG7WGX for the very useful answers. You've given me a starting point.