VALVES

Ellesmere Guardian, Volume XLVI, Issue 3211, 17 April 1928, Page 6

VALVES

Because a valve will light up it does not necessarily follow that it is O.K. The manufacture of a valve is a work of art and everything possible is done to ensure valves being the best possible. Even so, faulty valves often creep into the market and find their way into sets the • owners of which never suspect for a moment that anything is wrong simply because the valves light up. If a number of valves are tested after being in use for six months it is surprising how varying is their efficiency. While one may be found perfectly O.K. the others will probably be found to be considerably below par. This gradual falling off in efficiency is responsible for much of ' the falling .off in signal strength met with after a set has been in use 9 or 10 months. The valves may continue to light and cause no suspicion as tp their efficiency, but when tested their powers of amplification will inevitably be found to be well nigh nil. In actual practice every valve should be tested every six months and any valvo found ■•

to be faulty should be at once replaced if best results are to be obtained. The inclusion of even one faulty valve in a multi-valve set will cause a great deal of signal strength to be lost. The cutting out of one valve should result in an appreciable decrease in strength, but the extent of this decrease will depend upon several factors. The circuit and the amount, of high tension used will largely govern results. As a guide it may be said that if, with two valves, the volume is comfortable, with an additional Valve the increased signal strength should be such as to be almost objectionable when the set is going "all out."