Show ar AF ngaw P to 7 F A A 5 b GOV five tube tuned radio frequency two stage tuned radio detector and two stages of audio frequency R receiver using low loss doughnut in first stage the latest improvement in radio apparatus pa ratus the lie low loss doughnut t coll coil can be used in any of the and tuned radio frequency tu to stabilize the circuit its use in place of the customary coupler used for tuning tile the first stage will improve any existing receiver find Is a good piece of apparatus to incorporate in any re ceaver the interference noise and general tuning qualities of the first stage art are amplified and eventually become the output of the receiver if tile the first stage Is broad brand in tuning the received receive will very likely lack selectivity the action of tile the first stage hns has a great deal to do with the ultimate performance of the receiver usual type of transformer the usual type of transformer u used s d has a single layer wound coll coil on n R tube with a gnp taken off for the antenna connection the held field of the magnetic lines of force around the ends of tile the coll coil created by the of current through the lie wire spread t f and sprays nearby pieces of apparatus causing distortion and making the receiver unstable in operation the low loss doughnut cyp of coll coil on oil the other hand tins has nn an entirely self contained field that prevents lc spraying effects the low loss feature of the coll coil la Is due to the fact that the wires are indented at every other fare face around tile the coil thereby lowering the distributed and resistance losses below that of or ordinary binary linary coils to u noticeable degree to incorporate the coll coil in a regular or tuned radio frequency receiver all that Is necessary is to re move the present coll coil used tor for tuning the aerial circuit and replace it with a low loss doughnut coupler the same condenser can be used to tune the receiver providing it Is of mad capacity parts needed to construct the complete receiver as shown in the di diagram the following list of apparatus will be needed I 1 low loss doughnut coupler 2 radio frequency transformers tuned type low loss doughnut coll coil transformers may be used here with excellent results 8 3 mad variable condensers preferably straight line frequency low loss condensers so that the lower wavelength stations will be separated far apart enough to make tuning easy 6 15 standard vacuum tube sockets and five rheostats 25 ohm for the 0 A and 40 ohm for the C type tubes 2 low ratio kudlo frequency transformers for mera 3 to I 1 ratio 1 mad fixed grid condenser 2 grid leak single circuit phone jack binding posts wire a 7 by 24 or 26 inch panel and a 7 hy by 23 inch baseboard will complete the list of apparatus necessary follow out me he wiring diagram in building the lie receiver spacing tile alie regular tuned dudlo frequency transformers at least MA fla inches apart if tho the low loss doughnut coll coil transformers tire are used as well as the couil coupler r then the spacing can suit the arran arrandt bont of the rest of the apparatus fn an your set without fear of coupling |