General Description
The Hallicrafters S-85 Communications Receiver is designed for superior worldwide radio reception, covering frequencies from 538 kilocycles to 34 megacycles. It allows users to tune into foreign and domestic shortwave broadcasts, amateur radio, police, aircraft, and ship communications, as well as local standard broadcast stations. The receiver features a 7-tube super-heterodyne circuit for voice and code signal reception across its entire tuning range, complemented by a powerful built-in Alnico V permanent magnet speaker and a full-range tone control for lifelike audio reproduction. Satisfactory reception can often be achieved with the included 15-foot antenna wire, though an external antenna may enhance performance in certain locations.
Key features include calibrated electrical bandspread for precise tuning of amateur and shortwave bands, an automatic series noise limiter to reduce interference, a front panel headphone jack, a sensitivity control, an automatic volume control (AVC) circuit, and a receive-standby switch for silencing the receiver without powering it down.
Installation
Proper installation is crucial for optimal performance. The receiver is equipped with rubber mounting feet for table or shelf placement. Ensure adequate ventilation by allowing at least one inch of clearance at the back. The S-85 operates on 105-125 volts AC, while the universal S-85U supports 110-250 volts AC via a power selector switch. Users should verify their power source before plugging in the unit. Antenna connections are designed for single-wire or balanced/unbalanced transmission lines (52-600 ohms). The document details the setup for both single-wire antennas and half-wave doublet antennas, including formulas for calculating doublet length based on frequency.
Operation
The receiver's operation is managed through several controls, each serving a specific function. The Sensitivity Control adjusts receiver volume in conjunction with the Volume control, determining the ability to pick up weak signals. The Band Selector tunes the receiver to the desired frequency band. The Volume Control adjusts the audio output level. The AVC Switch maintains a uniform volume level for AM reception when set to 'ON', and should be set to 'OFF' for CW reception. The Noise Limiter Switch, when set to 'ON', helps reduce pulse-type noise interference. The Tone Control also functions as the receiver's on-off switch. The Pitch Control adjusts the pitch of code signals, active only when the AM-CW switch is set to 'CW'. The Standby-Rec Switch allows the receiver to be silenced without turning it off, maintaining tube warmth for instant use. Tuning is accomplished using the Tuning Control for wide tuning and the Bandspread Control for fine tuning, with specific instructions provided for using the main tuning dial and bandspread dial for accurate station identification and tuning.
Service Data & Alignment
This section provides essential information for maintenance and alignment. It lists the required equipment for alignment, including a signal generator, output meter, and non-metallic alignment tool. Initial control settings for alignment are detailed. The document outlines both IF alignment and RF alignment procedures, specifying the connections, frequencies, and adjustments for various components like trimmer capacitors and slugs. Diagrams illustrate the location of tubes, alignment adjustments, and the dial cord stringing process. A comprehensive service parts list categorizes components such as capacitors, resistors, coils, transformers, switches, plugs, sockets, tubes, and miscellaneous items, including their schematic symbols, descriptions, and Hallicrafters part numbers.
A voltage chart is provided, detailing DC and AC voltage readings at various tube sockets under specific operating conditions, which is crucial for troubleshooting and diagnosis.
