Options for using the Elecraft K4 for 2m EME
Dec 4, 2020
Background
Elecraft announced the K4 transceiver in May 2019 and I saw the radio at Ham Radio, Friedrichshafen in June 2019. I placed an order for a K4D (with an optional K4HD should I need it), in July 2019. Units started shipping in November 2020, maybe delivery will be Q1 2021?
Elecraft K4D
The K4D is a dual receive, direct sampling software defined radio (SDR) covering 100 kHz - 54 MHz. Each receiver has a set of filters and a 16-bit analog-to digital converter (ADC).
The raw IQ data streams for each receiver will be accessible via the Ethernet port. With suitable 144MHz - 14MHz (or 28MHz) receive converters it should be possible to use the K4D for adaptive polarisation reception with MAP65.
2m EME System Dec 2020
The existing receive system uses a ME2-RX, Afedri AFE822x, Linrad and MAP65 for dual polarity reception. An Elecraft K3 and Kuhne TR-144H transverter are used for transmit. There is also an option to receive either horizontally or vertically polarised signals via the TR144-H and Elecraft K3 using WSJT-X.
Signal paths with the K4D
144 MHz signals from the horizontal and vertical Yagis are converted to 14 MHz (or 28 MHz) by a two channel receive converter/transverter using a common local oscillator. The signals are routed to the first and second receivers in the K4D via the RX ANT 1 and RX ANT 2 (XVTR IF) connectors. Audio from each receiver is available via USB. This is routed to two instances of WSJT-X, one for horizontal and one for vertical signals. Raw IQ data for each receiver is available via the Ethernet port and is routed to the PC for additional processing.
144-14 MHz conversion
There are some different options for dual 144/14 MHz receive and 14/I44 MHz transmit.
- Use ME2-RX for receive and TR-144 H for transmit
- Replace ME2-RX and TR 144 H with a ME2-XP
- Upgrade TR 144 H to TR 144 Pro and use output from local oscillator for a second receive converter
After some consideration the third option was chosen.
