These units are so rugged and of such value to their owners that many are still in first-line use after over 30 years.

The system consists of a two-element, electrically switched yagi antenna and a double-conversion, crystal-controlled receiver mounted on a wooden frame. Its 3 dB antenna gain and .08 µV typical DF sensitivity allow this unit to hear and positively track a weak signal at very long ranges. The built-in RF gain control with 120 dB range permits positive DF to within a foot of a 1-watt transmitter.

It has no 180-degree ambiguity and the antenna can be rotated for horizontal polarization. The meter functions as a left-right homing indicator in normal use. The simple "turn toward the needle" operation permits inexperienced personnel to get 2° free-field accuracy even with intermittent or varying signals after a few minutes of instruction. The unit will DF on a signal that is too weak to be audible. Less than a half-second of signal is needed to register on the meter. A sensitive signal strength indicating mode is also provided for use with the supplied yagi or with other beam-type antennas.

With accessory antennas it can be used in a vehicle, boat, aircraft or fixed station, and as an interferometer.

Standard features include a lighted meter and shaped switch knobs for night operation, 12/24V auxiliary power jack; external phone jack, battery check push-button, and remote meter connector. The unit is designed for rough field use; the receiver is housed in a well shielded die-cast aluminum case and is water resistant to allow continuous operation in rain or snow and at sub-zero temperatures. The aluminum antenna elements will fold or bend, not break, on impact. Up to 30 hours’ operation is possible on a single pair of 9V alkaline batteries.

The LH Series Little L-Per  units come complete with receiver/DF, antenna (one for each band), 46" standard folding mast and 13" short mast, batteries, and operating and maintenance manual; some models include crystals (see price list). Two independent frequency ranges, such as 121.5/243 MHz aircraft, 121.5/VHF Marine, or 145/222 MHz Amateur can be covered in a single unit. A maximum of four crystals can be installed per tuner or six per receiver. Crystals are of a plug-in type and easily accessible to add at a later date for additional capability.