TM 11-6625-486-14&P
(1) Either vfo signal and any signal received
by the meter antenna (when the FUNCTION SW is set
uses two transistors and two crystals. One crystal is
to OPER).
accurately set at 1 MHz and the other at 2.5 MHz. The
setting of the RANGE SW determines which crystal is
(2) Either vfo signal and the crystal oscillator
used. Strong harmonics of the crystal oscillator output
signal (when the FUNCTION SW is set to CHK).
signal are obtained by the application of the signal to the
e. Mixer and Audio Amplifier. The mixer and audio
harmonic generators. The 1-MHz crystal provides a
amplifier circuit, using a transistor, functions as a low
minimum of 22 crystal checkpoints for calibrating the
frequency heterodyne mixer and audio preamplifier.
variable frequency oscillator (vfo) in ranges A and B.
The input signals, which consist of sum and difference
The 2.5-MHz crystal supplies a minimum of 27 crystal
frequencies plus harmonics, are heterodyned together to
checkpoints for range C. No power is applied to the
produce a beat difference frequency which is within the
crystal oscillator until the FUNCTION SW is placed at
audio range.
CHK.
f. Audio Amplifier. The audio amplifier circuit uses
three transistors to amplify the heterodyne beat note
contains two transistors and generates fundamental
(audio) received from the mixer so that it may be heard
frequencies that may be varied over a range of 125 to
in the headset.
250 kHz in range A, and 2.5 to 5.0 MHz in range B.
g. Modulator and Dial Lamp Power Circuit. The
Usable harmonics in both ranges cover frequencies up
modulator and dial lamp power circuit contains one
to 65 MHz and are obtained in the harmonic generating
transistor which functions as a 900-hertz audio oscillator
circuit.
to modulate either vfo and supply 900-hertz ac power for
two neon lamps.
The lamps light the filmstrip.
contains two transistors and generates fundamental
Modulating voltage is superimposed on the vfo direct
frequencies that may be varied over a range of 65 to
current supply when the FUNCTION SW is set to MOD.
130 MHz. Harmonics up to 1,000 MHz are produced in
h. Power Supply. The power supply operates on
the harmonic generating circuit.
either alternating current or batteries and provides
regulated and unregulated dc power for all transistor
circuit produces harmonics for the variable frequency
circuits.
oscillators or crystal oscillator in addition to serving as a
high frequency heterodyne mixing network. The input
signals may be either of the following:
NOTE
INDICATES EQUIPMENT MARKING.
EL6625-486-14-TM-10
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