Twelve good reasons for choosing the ‘870A’ 

7 March 2023


Technical information on the ‘EDDYSTONE 870A’ – the receiver that is equally at home ashore or afloat!


FREQUENCY COVERAGE. Five ranges cover the principal short, medium and long wave broadcast bands, as follows:-

Band 1 24 Mc/s. to 7.5 Mc/s. (12.5-40 metres)
Band 2 7.5 Mc/s. to 3.2 Mc/s. (40-93.9 metres)
Band 3 3.5 Mc/s. to 1.3 Mc/s. (85.7-230.7 metres)
Band 4 1400 kc/s. to 510 kc/s. (214-588.2 metres)
Band 5 380 kc/s. to 150 kc/s. (789.4-2,000 metres)

CIRCUIT AND VALVES. The five valve superheterodyne circuit is designed to give optimum performance. All valves are modern International types, readily obtainable anywhere. Special attention has been paid to the tuning coils, which are most efficient. These coils have adjustable dust-iron cores and air trimmers, ensuring consistently accurate alignment and uniform sensitivity.

TUNING DRIVE AND SCALE. Two main features of the “870A” receiver are the smooth drive and clear open scales. The drive is geared, with flywheel loading. The scales are clearly marked in frequency and the logging scale provides fine tuning. It also enables station settings to be recorded. The dial is edge illuminated with the recognised broadcast bands suitably indicated.

POWER SUPPLY. The “870A” receiver operates equally well from AC or DC mains supplies and an adjustment is provided for voltages of 100/120 and 200/250. The on/off switch, incorporated in the volume control, is of the double pole type, ensuring the complete isolation of the receiver from the mains when switched off. Both sides of the mains are fused and “Thermisters ” prevent sudden surges when switching on, leading to longer valve life.

Choke smoothing is employed, with high capacity condensers, ensuring an an output free from hum.

AUDIO OUTPUT. Adequate volume and good tonal quality is provided by the high efficiency speaker, in conjunction with negative feedback and a well-matched output transformer.

GENERAL CONSTRUCTION AND FINISH. A diecast front panel is used to ensure maximum rigidity. Components throughout are of the highest quality and the receiver is suitable for use in all climates.

The metal cabinet is finished in two-tone style with durable stoved enamel, giving a pleasing appearance and having the ability to stand up to hard usage. Chromium plated handles fitted to the front panel serve both for protection and for carrying the receiver.

Colour schemes are two tone Maroon, Green or Grey.

Access to the interior is readily obtained by removing four screws at the rear, when the cabinet can be detached.

MINIMISING INTERFERENCE. The “870A” receiver has been designed to minimise locally generated electrical interference. The internal filter unit, in series with the mains supply leads, prevents noise carried along the mains from entering the receiver. A metal cabinet is used to provide additional screening, a feature which is lacking with a plastic cabinet. The aerial sockets are arranged to take either a single wire aerial or feeders from a doublet aerial. The latter is recommended for noisy locations and is particularly suitable for use on board ship, and in areas having DC supply mains.

The mains connections and all plugs and sockets are completely insulated so that metalwork can be directly earthed.

WEIGHT, DIMENSIONS, ETC. Weight: 11½ lbs. unpacked. Width: 11¹⁄₁₆”. Depth: 8³⁄₁₆”. Height: 6⅜”. Consumption: 0.2 amperes.

INSTRUCTION AND GUARANTEE. The “870A” receiver is well packed and supplied with an Instruction Manual giving comprehensive information on installation, together with full technical details. A 12 months guarantee applies.



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Liverpool, Sunday 21 July 2024