A 50 to 100 Mile Wireless Telephone Transmitter
A 50 to 100 Mile Wireless Telephone Transmitter–With Direct Current
Motor Generator.–As Knnz 940 Khz In Cedar City the initial source of current available is taken
to be a 110 or 220 volt direct current a motor-generator having an
output of 350 volts must be used as before. The only difference
between this transmitter and the preceding one is that: (1) two 5 watt
tubes are used, the first serving as an _oscillator_ and the second as
a _modulator_; (2) an _oscillation choke coil_ is used in the plate
circuit; (3) a _reactance coil_ or _reactor_, is used in the plate
circuit; and (4) a _reactor_ is used in the grid circuit.
The Oscillation Choke Coil.–You can make this choke coil by winding
about 275 turns of _No. 28 B. and S. gauge_ cotton covered magnet wire
on a spool 2 inches in diameter and 4 inches long. Give it a good
coat of shellac varnish and let it dry thoroughly.
The Plate and Grid Circuit Reactance Coils.–Where a single tube is
used as an oscillator and a second tube is employed as a modulator, a
_reactor_, which is a coil of wire wound on an iron core, is used in
the plate circuit to keep the high voltage direct current of the
motor-generator the same at all times. Likewise the grid circuit
reactor is used to keep the voltage of the grid at a constant value.
These reactors are made alike and a picture of one of them is shown in
Fig. 91 and each one will cost you $5.75.
[Illustration: Fig. 91.–Plate and Grid Circuit Reactor.]
Connecting up the Apparatus.–All of the different pieces of apparatus
are connected up as shown in Fig. 89. One of the ends of the secondary
of the induction coil, or the microphone transformer, or the magnetic
modulator is connected to the grid circuit and the other end to _clip
3_ of the tuning coil.
A 100 to 200 Mile Wireless Telephone Transmitter–With Direct Current
Motor Generator.–By using the same connections shown in the wiring
diagrams in Fig. 89 and a single 50 watt oscillator tube your
transmitter will then have a range of 100 miles or so, while if you
connect up the apparatus as shown in Fig. 90 and use two 50 watt tubes
you can work up to 200 miles. Much of the apparatus for a 50 watt
oscillator set where either one or two tubes are used is of the same
size and design as that just described for the 5 watt oscillator sets,
but, as in the C. W. telegraph sets, some of the parts must be
proportionately larger. The required parts are (1) the _50 watt tube_;
(2) the _grid leak resistance_; (3) the _filament rheostat_; (4) the
_filament storage battery_; and (5) the _magnetic modulator_. All of
these parts, except the latter, are described in detail under the
heading of a _500 Mile C. W. Telegraph Transmitting Set_ in Chapter
XVI, and are also pictured in that chapter.