VALVE PRECAUTIONS

Shannon News, 7 December 1928, Page 3

VALVE PRECAUTIONS

Don’t handle valves roughly, or elements may bo injured.

Don’t burn valve filaments above or below rated amperage and voltage.

Don’t insert valves in sockets unless absolutely certain rheostats are at the proper setting for normal operation. Don’t make drastic error of connecting “B” battery to the filament term ■inals—-watch all battery connections. Don’t burn out a valve through carelessness and expect your dealer to exchange it for another. Don’t energise the filaments of all the. valves in a cascade circuit at once unless the circuit has been used before.

Don’t take one valve out oi' a cascade circuit in which the filaments are in parallel—it causes a rise in current in the remaining filaments and may burn them out. Cut off the current first.

Don J t make any alterations in your wires while valves are in their sockets. It is quite a common thing for 40 to 60 volts to become twisted up in the filament circuit, as a result of this practice. High voltage for the filament spells disaster for your valves. ’ Don’t expect a continued increase in signal strength as your filament temperature increases beyond normal. You will only reduce the life of your valve. Valves function best at one particular point—when you increase the filament current beyond this point you do the signal no . good and the valve great harm.

Don’t forget the necessary filament current may frequently be greatly, reduced by proper manipulation of the tuner circuits, especially the tickler or regenerative circuit, if used. Don’t expect to have a loud speaker operated from a detector valve—you’ll .be disappointed. At least one stage of audio-frequency amplification is generally necessary. , Don’t forget that valves cost from 6 to 8 times as much as ordinary incandescent lamps—they deserve a little respect.

i Don’t expect to get the best results if you use an amplifier valve for a detector, or vice versa.

i Don’t be anxious to produce sound with very great volume—it isn’t necessary.

Don’t expect your loud speaker to work properly if you hove a pair of phones connected to your detector circuit. ;