Variable step size. Input to the DDS is via a rotary encoder. Prototype with 2 x 16 line display. Top right - rotary encoder. Underneath the encoder is a biased toggle to select the DDS step size.
Display shows MHz.
In the Mk 2, the Toko filter has been replaced with a higher performance trapped low pass. The two high speed op-amps following the DDS have been replaced by a dual version.