A 25 to 50 Mile Wireless Telephone Transmitter
A 25 to 50 Mile Wireless Telephone Transmitter–With Direct Current
Motor Generator.–Where you have to start with 110 or 220 Southwest Colorado Tv Translator Association K24ch 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.
[Illustration: Fig. 86.–Telephone Induction Coil. (Used with
Microphone Transmitter.)]
[Illustration: Fig. 87.–Microphone Transformer. (Used with Microphone
Transmitter.)]
[Illustration: Fig. 88.–Magnetic Modulator. (Used with Microphone
Transmitter.)]
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.
The Microphone Transformer.–This device is built on exactly the same
principle as the telephone induction coil just described but it is
more effective because it is designed especially for modulating the
oscillations set up by vacuum tube transmitters. As with the telephone
induction coil, the microphone transmitter is connected in series with
the primary coil and a 6 volt dry or storage battery.