| OCR Text |
Show 1 INSTALLING VACUUM TUBE DETECTOR i . . A, BY K. Ij. DUNCAN THrcotor. Rcuiio Institute rr America No sooner Is the radio fan s"' i I li hi." crystal detector receiver than he tarts thinking about improvements. He vrants to covet b greater range with his little Instrument. Il- wants to hear more clearly lie finds the way out By substituting B vacuum tube detector de-tector for the irnlenn. This gives ;ip-pioxim.itely ;ip-pioxim.itely three times the receiving receiv-ing distance and a much greater ayudlbllliy But the amateur cannot make the Vacuum tube. It Is too complicated. consisting of a tungsten or tantulum filament, tungsten or copper grid and an aluminum or nickel plato en-l closed In a highly vacuumed dl.i-sl tube or bulb I To change over from the cry St A receiving sel the following are hec sary: A specially made socket for the tube's Mounting, Two batteries! A rheostat. HOW TO CONMJCr The connection should be according accord-ing t" diagram Xo 1. A Is the filament battery b bIx-volt bIx-volt i"i to ISO ampere hour battery which Is regulated by a small 1 1-'. ampere rheowtnt e little Instrument that regulates the flow of current from the battery. B Is the plate battery a dry battery bat-tery supplying 22 volts. It Is best to have the plate battery variable on account of the characteristics of the tbues. The flow of current should PENCIL OP INOIA INK LI ME. ENDING POiTi be regulated from IT 1-2 volts to tt volts It should be noted that the nepa-ive nepa-ive lead of the & battery is joined to the negative lead of the A bat-, terv through the hend receivers, forming the common negative. This Is essential for receiving the Incoming Incom-ing oscillation No. i represents the vacuum tube No, 2 fa the A oattery rheostat. i No. 3 Is tho grid condenser the( fixed condenser of the crystal s :. No, 4 is the grid leak I he con-, IstrUOtlOn of which is explained be-' j low. i N'o 5 the head receiver THE GRID LI U To make ;i grid leak lake a piece of stiff cardboard about one Inch I Wide by two Inches long. On this i mount two small binding posts about I 1 1-2 !bchea bng.- On this mount two small binding pots about i 1-2 Inches apart. Take a verj BOft le.nl pencil and draw twb lor three lines between the posts und I also around them I Grid le.ik shown In diagram No. 2; a is the plate; b the filament anil. c tho grin. The pencil lines act ns a conductor i of current. : l he purpose Is to allow the nega- 1 jtlve charge tp leak off the grid so that ii in.iy n-'t become clogged up I with chafglngs that will reduce the! a udlblli' i i n signals. |
