Note
CQ, Dec 1966, p. 30.
The HA-700 communications receiver is 6 tube superhetrodyne unit with two mechanical filters in the IF.. The sensitive IF stage incorporates a front panel controlled antenna trimmer and sensitivity of 1µV for 10 dB signal to noise ratio. Frequency stability is maintained by continuous filament voltage on the critical oscillator and mixer stages.
Features
– Variable BFO tone for improved CW reception.
– Flywheel operated tuning dials for smooth, fast tuning.
– Silicon diode automatic noise limiter and AVC circuitry for efficient noise suppression.
– Frequency Stability: Filament voltage is continuously supplied to the V2 mixer/oscillator tube—even when the receiver power switch is turned off—to maintain thermal equilibrium and minimize drift.
– Tuning System: Features a main slide-rule dial, an amateur bandspread dial with calibrated scales for major ham bands, a 0–100 logging scale, and an Antenna Trimmer (ANT TRIM) control.
– Controls & Metering: Front-panel S-meter (calibrated 1–9 and up to +40 dB over S9), BFO pitch control, RF-IF Gain, AF Gain, and headphone jack (which automatically mutes the 8-ohm speaker output).
– Remote Control / Muting: Includes an 8-pin rear octal socket for receiver muting/standby control when paired with an external transmitter or SSB transceiver.
Specifications
– Frequency Coverage: Features 5 bands covering 150 kHz to 400 kHz (LW/beacons) and 550 kHz to 30 MHz (AM broadcast and shortwave/HF amateur bands).
– Receiving Modes: AM, CW, and SSB (Single Sideband).
– Single-conversion superheterodyne design with a 455 kHz intermediate frequency (IF). It uses two 455 kHz mechanical filters to achieve high selectivity ±1.3 kHz at -6 dB, 5 kHz at –55 dB).
– Detector Stages: Uses a standard diode detector for AM, a dedicated product detector for CW/SSB, and an Automatic Noise Limiter (ANL) for AM.
– Audio output power is 1.3 watts into 4 or 8 ohms.
Tubes Lineup (6 total)
– 6BA6 (RF Amp)
– 6BL8 (Mixer & Local Oscillator)
– 6BA6 (1st IF Amp)
– 6BA6 (2nd IF Amp),
– 6AQ8 (Product Detector & BFO)
– 6BM8 (1st Audio Amp & Audio Power Output)
Diodes (7 total): 1N60 / SW-05S rectifiers and detectors, and FR-1K AC rectifiers.
References
Brief description. Electronics World, Nov 1966, p. 103.
