Show L 1 adith by 0 Dovi ilas editor of radio 3 if here Is I 1 a stunt for using one Varl ometer for two stages of tuned tin im gedanc radio frequency amplification there thera are only two principal controls Con by A L MUNZIG I 1 would like to present a novel means for tuned impedance control for radio frequency amplification tuned impedance offers twice the lie uon tion that transformer coupled types can give so BO why not uso use it obtain a standard make of varl and take it completely apart without disturbing the molded windings separate sepal ate the two stator elator winding and the two halves of the rotor winding bring out leads through small holes drilled in the rotor form Ai assemble and connect one side aide of the staid winding in series cerles with the corresponding halt half of the rotor do the same lame with the remaining stator and rotor halves thus we have two vario meters in one that change their mutual inductance simultaneously thereby doing away with an extra con arol allowing two stages of radio tre fro quency to be available minus several critical adjustments by shunting a small fixed condenser across each varl ometer they must be of the same capacity they can be made to function as radio frequency tuned impedance transformers on amateur anti ana broadcast wavelengths wave lengths the value of the capacity used depends on the waves to recovered be covered some of the readers may be dublo dubious ull about the practicability of this stunt due to the fact that both tuned er impedances pe dances aye are jn in too close proximity to each other however this to Is an advantage and not a detriment to the efficient operation of the amp amplifier lifler connections for two stages of tuned radio frequency amplification are ar shown in fig I 1 news |