Jottings

Radio Record, Volume V, Issue 25, 31 December 1931, Page 28

Jottings

yy practice it has proved so much better to use a grid-leak return to a potentiometer instead. of to the filament that this is now standard S.W. practice. A 10,000 or 20,000-ohin spaghetti. resistance in the plate circuip~ Oe au short-wave detector instead of an R.E. choke often decreases the tenden-_ cy to howling. "THRESHOLD howl can often be stopped by placing a .5 megohm or less resistance across the secondary of the audio transformer, though this may make a noticeable reduction in the amplification of the stage. AN easily-made improvement to many a short-wave set is to place an R.I. choke (or chokes) in one (or both) of the phone leads. i you are bothered with mains bum ~ ‘ on short-wave work try standing all the batteries on an earthed nn plate. ; pe not hang up telephones when not in use against an outer wall, as this intensifies their tendency to rust. PoE little cord near the telephone tags is intended to be fastened down to some immovable part: of the set, so that a pull on the cord will not weuken the connections inside it. \ HEN a milliammeter connected in the plate circuit of the last valve kicks to a lower value ou a loud pissage, it generally means that the gridbias: value is too. low. Pug loud hin often heard when attempting to work a pick-up 1s frequently caused by the pick-up leads iu the grid circuit being too long, V WEN an output or audio yanre is not being worked on its maximum ‘"B" voltage, it is sometimes possible to remove overloading distortion ; by applying all the extra voltage and readjusting grid bias to correspond,