Next connect one end of the grid condenser to the post of the tuning coil that makes connection with the microphone and the other end to the grid of the tube, and then shunt the grid leak around the condenser. Connect the + or positive electrode of the storage battery with one terminal of the filament of the vacuum tube, the other terminal of the filament with one post of the rheostat and the other post of this with the - or negative electrode of the battery. This done, connect clip 2 of the tuning coil to the + or positive electrode of the battery and bring a lead from it to one of the switch taps of the panel cut-out.
Now connect clip 3 of the tuning coil with one end of the blocking condenser, the other end of this with one terminal of the choke coil and the other terminal of the latter with the other switch tap of the cut-out. Connect the protective condenser across the direct current feed wires between the panel cut-out and the choke coil. Finally connect the ends of a lamp cord to the fuse socket taps of the cut-out, and connect the other ends to a lamp plug and screw it into the lamp socket of the feed wires. Screw in a pair of 5 ampere fuse plugs, close the switch and you are ready to tune the transmitter and talk to your friends.
A 25 to 50 Mile Wireless Telephone Transmitter--With Direct Current Motor Generator.--Where you have to start with 110 or 220 volt direct current and you want to transmit to a distance of 25 miles or more you will have to install a motor-generator. To make this transmitter you will need exactly the same apparatus as that described and pictured for the 100 Mile C. W. Telegraph Transmitting Set in [Chapter XVI], except that you must substitute a microphone transmitter and a telephone induction coil, or a microphone transformer, or still better, a magnetic modulator, for the telegraph key and chopper.
The Apparatus You Need.--To reiterate; the pieces of apparatus you need are: (1) one aerial ammeter as shown at E in Fig. 75; (2) one tuning coil as shown at A in Fig. 77; (3) one aerial condenser as shown at B in Fig. 77; (4) one grid leak as shown at C in Fig. 77; (5) one grid, blocking and protective condenser; (6) one 5 watt oscillator tube as shown at E in Fig. 77; (7) one rheostat as shown at I in Fig. 75; (8) one 10 volt (5 cell) storage battery; (9) one choke coil; (10) one panel cut-out as shown at K in Fig. 75, and (11) a motor-generator having an input of 110 or 220 volts and an output of 350 volts.
In addition to the above apparatus you will need: (12) a microphone transmitter as shown in Fig. 84; (13) a battery of four dry cells or a 6 volt storage battery, and either (14) a telephone induction coil as shown in Fig. 86; (15) a microphone transformer as shown in Fig. 87; or a magnetic modulator as shown in Fig. 88. All of these parts have been described, as said above, in [Chapter XVI], except the microphone modulators.
The Telephone Induction Coil.--This is a little induction coil that transforms the 6-volt battery current after it has flowed through and been modulated by the microphone transmitter into alternating currents that have a potential of 1,000 volts of more. It consists of a primary coil of No. 20 B. and S. gauge cotton covered magnet wire wound on a core of soft iron wires while around the primary coil is wound a secondary coil of No. 30 magnet wire. Get a standard telephone induction coil that has a resistance of 500 or 750 ohms and this will cost you a couple of dollars.