Note
QST, Apr 1964, p. 161.
Imported.
The Lafayette HE-73 "Precon" is a combination pre-selector and crystal-controlled converter unit. It is designed to be placed between an antenna and an amateur radio receiver to boost signal strength, improve sensitivity, and convert higher-frequency signals down to lower, more stable receiver bands.
Pre-selector Mode: Provides two tuned stages of RF amplification across all major HF ham bands (80, 40, 20, 15, and 10 meters) to increase receiver sensitivity and signal-to-noise ratio.
Converter Mode: Operates as a crystal-controlled front end on 20, 15, and 10 meters. It converts these high-frequency bands down to a 3.5 MHz to 5.2 MHz output range, effectively turning single-conversion receivers into double-conversion units with better stability and bandspread. On 80 and 40 meters, the unit defaults to pre-selector operation.
Off / Pass-Through Mode: Completely bypasses the unit, routing the antenna directly to the receiver while removing AC power from the HE-73 circuit.
Frequency Range (Preselector Operation):
80M: 3.5–4.0 MHz
40M: 7.0–7.3 MHz
20M: 14.0–14.35 MHz
15M: 21.0–21.45 MHz
10M: 28.0–29.7 MHz
Frequency Range (Converter Operation):
20M: 14.0–14.35 MHz (Converter Output: 3.50–3.85 MHz)
15M: 21.0–21.45 MHz (Converter Output : 3.50–3.95 MHz)
10M: 28.0–29.7 MHz (Converter Output: 3.50–5.20 MHz)
Oscillator Crystals:
20M Band: 5,250 kHz
15M Band: 8,750 kHz
10M Band: 12,250 kHz
Input & Output:
Antenna Input: 52 ohms, coaxial connector provided
Output Impedance: Low Impedance, coaxial connector provided
Tube Complement (3 total)
– 6BA6 (RF amp)
– 6BL8 (Mixer and oscillator / converter, or RF amp for preselector)
– 6BA6 (Cathode follower)
Power Requirements: 117 VAC, 50–60 Hz, 18 watts
Rear Panel Connections: Features standard SO-239 coaxial jacks for Antenna and Output, plus a Remote Control Socket. The remote socket allows external switching (such as from a transmitter's T/R relay) to cut B+ voltage and mute the HE-73 while transmitting.
References
Brief description. Electronics World, Aug 1963, p. 89.
Brief description. Popular Electronics, Jan 1964, p. 58.
Review: CQ, Jan 1964, p. 31.
