SB220 50MHz Modifications

1) Move the 10-meter tap on the plate coil (L6) to a point 1-2/3 turns from the plate-tune capacitor. A grid-dip oscillator can be used to check resonance at 50 MHz.

2) Unwind the 10-meter input coil (L1), leaving 2-3/4 turns.

3) Replace C33 and C34 by a single 10 pF mica capacitor.

4) Change C35 (115 pF) to a 33-pF mica capacitor. 

This change to my SB-220 has proved to be an excellent addition to the 6-meter setup. -  John Roth, WA2TSJ