Harris RF-551A Automatic Preselector Showing Impedance Tuner Matching

This video is a brief demonstration to show the operation of the Harris RF-551A preselector. During this brief video, the frequency is changed to show how the cams change the tuning capacitance.
Larger jumps in tuning frequency require more noticeable tuning match. Smaller shifts in frequency show slight shifts in tuning capacitance.

The RF-551A is a scarce unit that was sold by Harris during the days of the RF-550 receiver, but this preselector can be applied to any receiver. You attach the antenna to the preselector and connect it to the receiver via a coaxial cable with BNC connectors on each end.