Included with all new K2s, s/n 3000+
Replaces L33 in the BFO oscillator with a new prewound 41uH toroidal inductor that has a more temperature stable core. Replaces the two 12.096 crystals in the PLL ref. osc. with a single crystal for better temperature stability.
Improves BFO temperature stability on older K2s (less than s/n 3000.) Also improves SSB carrier rejection on older K2s that had a solenoidal inductor at L33.