Receiver local oscillator tracking.

The multi-gang circuitry and calculations were devised in the 1920's
with
the advent of the Superheterodyne Receiver and the 1930's multi-grid
frequency-changer tubes. All had to be extremely tediously worked out
with
slide-rules or log tables. Just think what the old boys could have
accomplished had this program then been available.

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I wouldn't be surprised if Edwin Armstrong could do it in his head.

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To solve the problem of calculating the four values of the trimming and
padding capacitors, two coil inductances, for given capacitance of the main
two-gang tuning capacitor, and for given edges of the frequency band,
involves the solution of four simultaneous quadratic eequations.

Edwin would have needed the assistance of at least a pencil and an empty
cigarette pack.