The Apparatus and Connections
The Apparatus and Connections.–The aerial series condenser, the
blocking condenser, the grid condenser, the telegraph key, the
chopper, the choke coil in the key circuit, the filament voltmeter and
the protective condenser in the power circuit are identical with those
described for the 5 watt transmitting set.
The 50 Watt Vacuum Tube Oscillator.–This is the size of tube
generally used by amateurs for long distance continuous wave
telegraphy. A single tube will develop 2 to 3 amperes in your aerial.
The filament takes a 10 volt current and a plate potential of 1,000
volts is needed. One of these tubes is shown in Fig. 80 and the cost
is $30.00. A tube socket to fit it costs $2.50 extra.
[Illustration: Fig. 80.–50 Watt Oscillator Vacuum Tube.]
The Aerial Ammeter.–This should read to 5 amperes and the cost is
$6.25.
The Grid Leak Resistance.–It has the same resistance, namely 5,000
ohms as the one used with the 5 watt tube transmitter, but it is a
little larger. It is listed at $1.65.
The Oscillation Choke Coil.–The choke coil in the power circuit is
made of about 260 turns of No. 30 B. & S. cotton covered magnet wire
wound on a spool 2-1/4 inches in diameter and 3-1/4 inches long.
The Filament Rheostat.–This is made to take care of a 10 volt current
and it costs $10.00.
The Filament Storage Battery.–This must develop 12 volts and one
having an output of 40 ampere-hours costs about $25.00.
The Protective Condenser.–This condenser has a capacitance of 1 mfd.
and costs $2.00.
The Motor-Generator.–Where you use one 50 watt oscillator tube you
will need a motor-generator that develops a plate potential of 1000
volts and has an output of 200 watts. This machine will stand you
about $100.00.
The different pieces of apparatus for this set are connected up
exactly the same as shown in the wiring diagram in Fig. 78.
A 1000 Mile C. W. Telegraph Transmitter.–All of the parts of this
transmitting set are the same as for the 500 mile transmitter just
described except the motor generator and while this develops the same
plate potential, i.e., 1,000 volts, it must have an output of 500
watts; it will cost you in the neighborhood of $175.00. For this long
distance transmitter you use two 50 watt oscillator tubes in parallel
and all of the parts are connected together exactly the same as for
the 200 mile transmitter shown in the wiring diagram in Fig. 79.
CHAPTER XVII
CONTINUOUS WAVE TELEGRAPH TRANSMITTING SETS WITH ALTERNATING CURRENT
Within the last few years alternating current has largely taken the
place of direct current for light, heat and power purposes in and
around towns and cities and if you have alternating current service in
your home you can install a long distance continuous wave telegraph
transmitter with very little trouble and at a comparatively small
expense.
A 100 Mile C. W. Telegraph Transmitting Set.–The principal pieces of
apparatus for this transmitter are the same as those used for the _100
Mile Continuous Wave Telegraph Transmitting Set_ described and
pictured in the preceding chapter which used direct current, except
that an _alternating current power transformer_ is employed instead of
the more costly _motor-generator_.
Wnlc 98.7 Mhz In East Lyme The Apparatus Required.–The various pieces of apparatus you will need
for this transmitting set are: (1) one _hot-wire ammeter_ for the
aerial as shown at E in Fig. 75, but which reads to 5 amperes instead
of to 2.5 amperes; (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 _telegraph key_ as shown at G in Fig.
75; (6) one _grid condenser_, made like the aerial condenser but
having only two terminals; (7) one _5 watt oscillator tube_ as shown
at E in Fig. 77; (8) one _.002 mfd. 3,000 volt by-pass condenser_,
made like the aerial and grid condensers; (9) one pair of _choke
coils_ for the high voltage secondary circuit; (10) one
_milli-ammeter_; (11) one A. C. _power transformer_; (12) one
_rheostat_ as shown at I in Fig. 75, and (13) one _panel cut-out_ as
shown at K in Fig. 75.