Connecting and configuring the Elecraft K3 or K4 for PSK, RTTY, CW, and Phone operation
de Rich, VE3KI
Connections
an audio cable from the transceiver's Line Out jack to the sound card's Line In jack (an external isolation transformer is not necessary, as it's built in to the transceiver)
an audio cable from the soundcard's Line Out jack to the transceiver's Line In jack (an external isolation transformer is not necessary, as it's built in to the transceiver)
a PTT connection, which can use any one of three possibilities (see Note 1 below):
PTT via the Xcvr Ctrl App option on the PTT tab of WinWarbler's Configuration window, with Commander configured to accomplish RX-TX switching by asserting the RTS or DTR hardware signal line on its primary CAT serial port without an interface circuit. and with PTT via CAT disabled (See Note 2 below for configuration instructions)
PTT via the Xcvr Ctrl App option on the PTT tab of WinWarbler's Configuration window, with Commander configured to accomplish RX-TX switching by sending CAT commands, or
PTT via the RTS or DTR option on the PTT tab of WinWarbler's Configuration window, which enables WinWarbler to accomplish RX-TX switching by asserting RTS or DTR on a separate serial port through an external interface (note that WinWarbler cannot use the same serial port as is being used by Commander for CAT control)
WinWarbler can transmit CW via the transceiver without any external CW interface; on the CW tab of WinWarbler's Config window, set the Keying Mode panel to Xcvr Ctrl App, and enable the transceiver's VOX function.
If this method is used, the Esc key cannot be used to interrupt a macro message in progress
Alternatively, an external CW interface can be used. WinWarbler does not support hardware CW keying directly via the DTR or RTS line on the transceiver's serial port as described in the transceiver Owner's Manual.
a FSK connection (if FSK RTTY operation is desired)
transceiver Configuration
The transceiver's factory default Line In level is 0, which prevents transmission in either PSK or AFSK RTTY. To set this level to a reasonable value,
set the 'Mic Sel menu item to Line In
set the Microphone Gain to 20
PSK Configuration
For PSK with WinWarbler, the transceiver should be in DATA mode, DATA A submode. In WinWarbler's Configuration window, under the PSK tab, I have the Receiver modulation and Transmitter modulation panels set to BPSK USB, and the transceiver mode panel set to Data-U. The optimal offset is set to 1500, which is where the transceiver's filters are centred in DATA A submode. The default TxPwr should be set to 50 watts or less in PSK mode to avoid IMD due to clipping on peaks.
AFSK RTTY Configuration
For AFSK RTTY, the transceiver should be in DATA mode, AFSK A submode.
In WinWarbler's Configuration window, under the RTTY tab, set the Modulation and transceiver mode panel to AFSK LSB, the Xcvr mode to RTTY, the Mark offset to -2125, and the Optimal Offset to 2210 (that's with the transceiver's Pitch control set to 2125 in AFSK A. For other pitch settings, set the Mark offset to the negative of the Pitch and the Optimal Offset to Pitch+85). If WinWarbler's Mark offset and Optimal Offset are not consistent with the transceiver's Pitch setting, the transceiver's internal filter may prevent RTTY audio from being transmitted.
On the General tab of Commander's Configuration window, set the RTTY sub-mode to AFSK. In contrast to PSK, there is no need to restrict the transceiver's power output in RTTY.
FSK RTTY Configuration
For FSK RTTY, the transceiver should be in DATA mode, FSK D submode. In WinWarbler's Configuration window, under the RTTY tab, set the Modulation and transceiver mode panel to FSK LSB, the Xcvr Mode to RTTY, the Mark offset to -2125, the Optimal Offset to 2210 (as described above for AFSK RTTY), and the FSK Control to the serial port you are using for FSK keying. On the General tab of Commander's Configuration window, set the RTTY sub-mode to FSK. With the transceiver's DATA submode set to FSK D, you may need to ensure that the transceiver's FSK speed is set correctly (45 bps is the normal setting for amateur RTTY). In contrast to PSK, there is no need to restrict the transceiver's power output in RTTY.
Notes
Do not use both CAT control and RTS/DTR PTT connection methods in parallel. Some transceiver owners who have done this have reported that their radio sometimes refuses to switch from TX to RX when both methods are used simultaneously, leaving it hung up in transmit. A single PTT mechanism is sufficient and avoids this possible race condition.
To use PTT via RTS (or DTR) on the transceiver's serial port,
On the General tab of Commander's Configuration window, check the Suppress CAT box
On the Ports tab of Commander's Configuration window, set RTS to TX
On the PTT tab of WinWarbler's Configuration window, set the Port to Xcvr Ctrl App
Set the transceiver's CONFIG:PTT-KEY menu item to RTS-OFF
The transceiver can be directed to transmit CW, report decoded CW, transmit RTTY, and report decoded RTTY via CAT commands. Commander and WinWarbler can be configured to use this capability, permitting CW and RTTY operation without external interfaces.