Stancor Model ST-202-A fulfills the demand for a compact,
desk type, high frequency, radio transmitter having
substantial power output- Internal circuits for
radiotelephony were purposely omitted to satisfy the
“strictly CW1' operator as well as to offer the "phone man11
a choice of either amplitude or frequency modulation. Hence,
either type of modulation may be ultimately applied.
Such important features as six band coverage (10, 11, 15,
20, 40, and 80 meters),
inter- and intra-band flexibility, and extreme simplicity of
adjustment and control w ere
included without resorting to complexities. Base of
construction was given paramount consideration in the design
of this unit.
The ST-202-A incorporates a novel and highly simplified
band-switching exciter circuit involving only two receiving
type tubes, a single deck coil turret, and one tuning
capacitor. The radio frequency power amplifier employs a
triode transmitting tube in a balanced, neutralized circuit
for stable, trouble-free operation. For this position,
several tubes are recommended (see ACCESSORIES) and a choice
may be made according to the dictates of the individual
operator. To meet all of the requirements of the various
triodes listed, the ST-202-A provides a range of amplifier
filament voltages of 5.0, 6.3, and 7.5, and a wide range,
neutralizing capacitor. The amplifier tank circuit uses 150
watt plug-in inductors of standard availability, one being
required for cach major frequency range. A link coil, with
variable coupling adjustment, facilitates proper loading of
the amplifier by the antenna system. Quick channel shifting
is accomplished by pancl-switch selection of six different
Separate power supplies develop 350 volts DC for the exciter
stages and 1,000 volts DC for the amplifier stage. The
exciter power supply is electrically inverted so that it may
also provide a grid bias potential for the amplifier tube.
Further, this system allows simultaneous screen keying of
both exciter tubes, giving clean-cut, telegraphic signals
along with the highly desirable “break-in” feature of operation.
Both grid and plate current readings of the final amplifier
tube arc taken with a
single milliammeter employed in a switching system.
Suitable terminals at the rear of the cabinet provide
connections to an antenna system, a telegraph key, a remote
standbyr switch, an antenna changeover relay, and an
amplitude modulator. An extractor type fuse receptacle and
the 117 volt AC line cord are also located at the rear.
The output of a frequency modulator or a variable frequency
oscillator may be introduced into one of the six crystal