Anti-Microphonic Valve Holder

Anti-Microphonic Valve Holder This component is built on anti-capacity lines, the valve legs all being spaced apart, while each is surrounded by a thin sheath of insulating material. The metal parts of the sockets are sunk beneath the top of these insulating sheaths, so as to safeguard the valve if any attempt is made to insert it incorrectly. In order to obviate even that, the anode pin is marked with a red ring so that no mistake shall be made. The valve legs are carried on a round disc of insulating material, a hole being drilled through the centre of this still further to reduce the capacity of the valve holder. The base is supported by means of flat leaf springs on a thin shell of insulating material which may be fixed to the baseboard, and it has a definite limit to its travel either upwards or downwards. Connections may be made by means of screws or soldering tags, and the general finish of the component is good, although the construction is some what on the light side.
Several valves were tried in the holder, and all were found to be a good tight fit, assuring that good electrical contact be made to each of the pins. The insulation resistance between pin to pin was found to be infinity in each case, and it is clear that considerable care and thought have been expended on its construction.
Modern Wireless, October 1928, page 520.

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Elenco delle radio e altri apparecchi della Harlie Bros.Ltd., London