Here’s the SV1EIA usb2sdr board controlling the Si570 chip on the vfo kit from K5JHF/K5BCQ, the MCU and display unit are of course removed. And the Si570 board is clocking the LA6NCA QSD unit. I haven’t calibrated anything yet, but it works fine.
Simple usb2sdr receiver setup. Top: K5JHF/K5BCQ Si570 board. Left: LA6NCA QSD board. Right: SV1EIA USB2SDR board.
Receiving wspr with the simple sdr setup.
The K5BCQ, like most, if not all SI570 based oscillator, suffers from backround mush and noise, as the frequency is tuned, especially in slow tuning mode. In order to minimise this artifact, we have to freeze the DCO, by the controller software, something kit manufacturers are reluctant to do for some unknown reason.