Show Variable to Take Up Little Room No two sets operate on the same value of ot resistance when using the re- re re coupled type of ot fre audio tre quency amplification The resistance should be adapted to the character- character nr used the ot at 01 at 01 01 or me the e tunes tUDes e me aging the tubes and the changing voltage otage ot of the B 11 battery Variable resistance may be made mode so soIlS IlS as to occupy very little room Nearly all commercially made variable resist resIst- ances are so made that It Is awkward to mount them The diagram Indicates a saving room method Use a base or of hard rubber or 2 by 11 by 3 10 3 Inches which Is s slit silt In two places about three fourths of ot the length of ot the block The resistance element Is s made by dipping a strip of ot cardboard In waterproof India Ink The are usually arranged In pairs one ot of the re making ng contact with P 0 s I e r I CC Leads Eliminated and Efficiency of at Set Is Increased d the plate and B plus pIus supply the other making a connection from the grid grill ot of the amplifying tube to the filament Sliders are arc made from sheet brass and electrIcally connected to the contacts at one end of ot the tho resistance by a sol dered flexible wire Be ne sure that tile the flexible wires are well Insulated Roller contacts on the India Ink resistance Insure that the Ink will not be scraped off or Injured These rollers are tire made by mounting about four of ot the ordinary spacing washers from commercial varIable condensers on a one eighth one Inch Inch brass bar Be certain that the pressure of ot the rollers on the resist resist- resistance resistance ance strip Is firm finn and secure The figure shows how this unit may maybe maybe maybe be placed between two tube sockets In n such a manner as to conserve space and save wiring all but one lead to the B plus supply Long binding post bolts are substituted for tor the short ones usually found In n commercial tube sockets and the variable resistance unit and the fixed condenser are bound to the tho socket terminals with the Ule same bolts Radio Radio News Nets |