cahill: Description of Pelican Four -Valve Set.

ID: 624850
cahill: Description of Pelican Four -Valve Set. 
21.May.23 02:51
300

Gary Cowans (AUS)
Editor
Articles: 106
Gary Cowans

Description of Pelican Four-Valve Set.

From Modern Wireless, March 1926, Page 803 & 804.

Pelican Receiving Set

A novel portable four-valve receiving set has been sent to us for testing by Peel Cahill & Co., Ltd.

Makers Claims

This set has been primarily designed to provide an instrument for receiving at least two stations in all parts of England, viz., the local station and Daventry
Provision is made for outside aerial and earth connections, while panel controls have been reduced to a bare minimum.

Description of Set

The set complete with batteries, frame aerial and loudspeaker is contained in a well-finished wooden cabinet about 17” by 16”, with a leather handle at the top for carrying purposes. Double doors are opened for access to the control panel, which has mounted on it a vernier dial tuning condenser (Pelican Univernier type), a filament rheostat control, a push-pull valve switch, and a long and short-wave change-over switch. Beneath this panel is the loudspeaker opening.

On closing the doors the valve switch is automatically brought into operation, cutting off the accumulator supply to the valves.

A side door can be opened for viewing all the components. The loudspeaker, which is of the high resistance, portable type, manufactured by A. Graham & Co., is situated in the bottom half of the cabinet with the HT and LT batteries. A horizontal shelf is employed to support all the other accessories in the top half of the cabinet.

The set itself consists of one HF, one detector, and two LF valves. The eight-pole double throw-over switch is used in one position to put three aerial loop circuits in parallel and a low wavelength transformer between the first and second valves, and in the other position the three aerial loop circuits are in series and a high wavelength transformer is connected between the first and second valves. The aerial is located in one of the cabinet sides and consists of a number of spiral turns of three parallel wires wound on a length of insulating strip, each turn being well-spaced. Dull emitter valves are employed in anti-microphonic holders, and a 30 ampere-hour accumulator of the non-spillable type is used for the LT source.

Laboratory Tests

The set was tried at our laboratories 13 miles from 2LO and about 60 miles from 5XX. Both stations were received at full loudspeaker strength, and the sharpness of the tuning made the vernier dial of the condenser a necessity. Capacity reaction is accomplished with the aid of a small adjustable condenser inside the cabinet. The frame aerial was very efficient, and good directional effects were obtained by rotating the whole cabinet. Oscillation is also controlled by adjusting the filament rheostat, but when tried on an outside aerial, this control made the set difficult to handle. Birmingham, Newcastle and Radio Paris were, however, heard on the loudspeaker in this case.

General Remarks

The set fully justifies the makers' claims in as much as it is an efficient two-station portable receiver. It is rather heavy to carry, as the complete weight is about 30 lb. The oscillation control from the filament rheostat may be improved by using a fine vernier to prevent it from being so critical. Other combinations of valves were tried, but it was found that the best is recommended by the makers, i.e., two DE2(M.O.) valves for the first two stages and two SP.8 (Cosmos) valves in the L.F. amplifying stages.

The convenience of having every accessory contained in one cabinet is a feature that will commend itself to many people. The quality of the reproduction in the loudspeaker was not considered good, but it is difficult to expect a complete self-contained receiving set of this type and size to be absolutely efficient from every standpoint. 

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