TM 11-6625-586-45
can be set at 62,500; 125,000; 250,000; or 500,000
INT MOD VOL control R23. The output of the
modulation amplifier is also provided to the meter
microvolt by RF OUTPUT switch A4S1.
j. 1 MHz Crystal Oscillator. The 1 MHz crystal
amplifier-detector and the isolation amplifier.
c. Deviation Metering. The meter amplifier, trans-
o s c i l l a t o r , transistor A6A1A1Q1, provides a
istor Q5, and the full-wave rectifier, diodes CR3 and
0.00375% or better frequency accuracy at 1 MHz
intervals in each of the four frequency bands. The
CR4, supply a rectified dc voltage to DEVIATION
crystal-controlled oscillator is located in constant
meter M1 that is proportional to the frequency mod-
temperature oven to minimize frequency changes
ulation. The DEVIATION meter has three ranges
due to temperature variations. The precise 1 MHz
and the extent of the deviation is controlled by the
DEVIATION control R23, which also serves as INT
output is applied to a harmonic generator.
k. Harmonic Generator. The 1 MHz output of the
MOD VOL control for the INT MOD OUT audio
frequency output available at J4.
crystal oscillator is applied to a harmonic generator,
d. Isolation Amplifier. The isolation amplifier,
transistors A6A1Q1 and A6A1Q2, which produces
harmonically-related signals throughout the fre-
transistors Q6 and Q17, serves to isolate the devia-
quency range of the generator. The harmonic spec-
tion metering circuit and the modulation amplifier
from the shaping network and RF oscillator that
trum is applied to a mixer.
l. Beat Note Mixer and Amplifier. The beat note
follows it.
mixer A6A1CR1 receives the harmonic spectrum
A1A1CR1 through A1A1CR8, serves to shape the
quency from the RF oscillator. When the signal fre-
modulation of the RF oscillator has the proper
quency is at any 1 MHz increment in the entire
characteristics.
frequency range, a zero beat between the 1 MHz
crystal oscillator and the signal frequency will occur.
A1A1Q1, generates the radio frequency selected by
If the frequencies differ, a beat note will occur. The
the RF TUNING control and the BAND SWITCH.
beat not is amplified by transistors A6A1Q3,
The oscillator is located in a constant temperature
A6A1Q4, Q7 and Q2 and is reproduced by
oven to minimize frequency changes due to temper-
loudspeaker LS1 if it is within the audible range.
ature variations. A turret contains the four tuning
When the beat note is reduced to zero, the RF oscil-
coils for the four frequency bands of the generator,
lator is tuned to a 1 MHz increment and the CAL
and the operation of the BAND SWITCH selects the
CORRECT knob can be adjusted to correct the dial
proper tuning coil and positions a dial mask to expose
reading.
the frequency scale for the selected band. The RF
m. IF Crystal-Controlled Oscillator. The IF
TUNING control provides two ratios of tuning con-
trol, a fast tuning ratio when the knob is pushed in,
crystal-controlled oscillator, transistors A2A1Q1 and
A2A1Q2, provides a choice of six crystal-controlled
and a fine tuning ratio coupled to a mechanical
counter of 20:1 when the knob is out. The CAL COR-
IF's, with an accuracy of 0.005%. Two additional
RECT knob moves the dial cursor for exact calibra-
switch positions are provided for additional IF's in
tion at the cardinal 1 MHz divisions in the frequency
the frequency range from 4 to 15 MHz. The IF UV
control adjusts the IF power level applied to the IF
calibration function.
g. Low RF Output. The RF output of the RF oscil-
amplifier.
n. IF Amplifier. The IF amplifier, transistors
lator is inductively coupled to piston attenuator
A2A1Q3 and A2A1Q4, amplifies the IF crystal oscil-
A1A2, which provides an RF output at the LO RF
output jack, J1 of 0.05 to 10,000 microvolts. The RF
lator output sufficiently to provide a maximum power
oscillator output is also applied to the low RF detec-
level of 1.0 volt. The IF detector A2AlCR1 provides a
tor A1A2A2CR1, which supplies a detected signal
means of setting the constant power reference level,
in the manner described for the low RF output.
used to set a constant power reference level on the
o. IF Output. With the constant power reference
RF-IF meter M2. At the constant power reference
level the LO RF UV dial reads directly in microvolt.
level maintained, the IF output jack J3 can be set at
h. RF Amplifier. The RF amplifier, transistors
10; 100; 1000; 10,000; 100,000; or 1,000,000 microvolts
A1A1Q2 and A1A1Q3, amplifies the RF oscillator
with IF OUTPUT switch A3S1.
p. Power Supplies. The 12-volt power supply,
output and provides a maximum level of 500,000
microvolt. The high RF detector A4GR 1 provides a
bridge rectifier CR9 through CR 12 and associated
means of setting the constant power reference level,
transistors provides +12 volts dc and --12 volts dc.
The 25-volt power supply, rectifier bridge CR5
in the manner described for the low RF output.
i. High RF Output. With the constant power refer-
through CR8 and associated transistors provides
+25 volts dc.
ence level maintained, the HI RF output at jack J2
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