Note
QST, Apr 1973, p. 163.
Ham Radio, Dec 1974, p. 70.
Uses LC tuned circuits and an IC amplifier it features accurate tone frequency, low drift, and immunity to RF pickup and interference.
An important application is tone-burst entry to two-meter repeaters. Many repeaters require a short burst of an audio tone for access. Each repeater in a local area and on the same or nearby frequency uses a different tone; this prevents accidental turn-on of other repeaters.
Eleven tones, from 1650 to 3000 Hz, are in widespread use. The Palomar Engineers encoder produces all eleven tones as selected by a front-panel switch.
The Palomar encoder has a built-in half-second timer. The time is adjustable
and can be wired to produce a continuous tone for other remote control applications.
Requires 12 VDC, Outputs for both high and low impedance microphones are provided so the unit may be used with all popular FM transceivers.