I checked the source code on Ian's, KD8CEC, github account and found that there are two different limits for frequency limits:
// limits the tuning and working range of the ubitx between 3 MHz and 30 MHz
#define LOWEST_FREQ (3000000l)
#define HIGHEST_FREQ (30000000l)
//When the frequency is moved by the dial, the maximum value by KD8CEC
#define LOWEST_FREQ_DIAL (3000l)
#define HIGHEST_FREQ_DIAL (60000000l)
Based on the descriptions only (I will need to dig in deeper to see if this is true), I would suggest you go to the 80 meter band and tune down manually from there.
The alternative is to change the #define LOWEST_FREQ (3000000l) to a value lower than the station you want to receive. Then recompile and download.