2-53. Audio Input/Output Connectors.
2-48. Frequency Change. The frequency
) signal is generated each
The audio connectors J1 and J2 enable
the operator to connect a handset or
time a new operating frequency is
headset and microphone combination to
selected. The AF signal is momentary
the radio set. A CW telegrapher's key
0 (grid) during each change in setting
of the frequency select switches S1
can be substituted for the microphone
for code operation.
thru S5. AF is not generated by S6.
The AF signal indicates to the
modulator/demodulator that a new
2-54. Handset or Headset and Microphone
Operation. When a handset or headset
frequency has been selected.
and microphone are used in conjunction
2-49. Volume off/max (left half of
with the radio set, they are connected
figure). The VOLUME OFF/MAX S9 is a
to the control panel by audio input/
conventional on/off switch and poten-
output connectors J1 and J2. The push-
tiometer. The switch, when closed,
to-talk (PTT) signal and the Xmt Audio
applies +28v On power from the bat-
are routed through the low-pass L-C
tery pack to the MODE, SB, and LIGHT
filter networks contained in the audio
switches on the control panel, and to
filter to the modulator/demodulator.
all radio set circuits. The potenti-
The audio filter rejects any rf which is
ometer R1 controls the level of Rcv
picked up by the cables leading to the
Audio developed by the modulator
radio set from the microphone or hand-
demodulator by tapping off a portion
set. The PTT is used by the modulator/
of the audio (from the VOLUME control)
demodulator to key the modulator for
back to the modulator/demodulator.
transmit operation. Rcv Audio from the
modulator/demodulator is also routed
2-50. Mode. The MODE (mode select)
through the audio filter to the handset
switch S8 provides both a +28v Xmt
Enable and/or a Data Enable signal to
the modulator/demodulator. The Xmt
2-55. CW Key. A cw telegrapher's key
Enable signal (V-TR and D-TR) permits
is normally used in conjunction with a
Xmt RF to be generated by the modulator/
headset, but can be used with a handset.
demodulator when the modulator is keyed.
The cw telegrapher's key outputs a CW
The Data Enable signal (DTR) indicates
Key signal which is filtered and routed
to the modulator/demodulator that a
to the modulator/demodulator. The CW
data transmission has been selected.
Key signal is used by the modulator/
The modulator/demodulator will cause
demodulator to activate the keyline
the receiver agc time constant to be
circuits and internal 1-kHz modulation
shortened. When a voice receive (V-RCV)
or data receive (D-RCV) has been
selected, the +28v Xmt Enable signal
SYNTHESIZER MODULE (Figure 2-5).
is inhibited, preventing transmission
(receive operation only).
2-57. General. The synthesizer pro-
vides input to the modulator/demodulator
2-51. Sideband Select. The SB (side-
in the form of three high frequency LO
band select) switch S7 applies either
signals and one audible tone. The high
an upper (USB-open) or lower (LSB +28v)
frequency LO signals are 5 MHz, 70/80
Sideband Select signal to the synthe-
MHz, and 77-105 MHz. The 70-MHz LO
sizer. The signal is used to switch the
signal is outputted if USB is selected
70/80 MHz LO to provide either upper or
and the 80 MHz is outputted if LSB is
lower single sideband operation.
selected. The frequency of the 77-105
MHz LO signal is 75 MHz above the fre-
2-52. L i g h t The LIGHT switch S10 is a
quency selected at the control panel.
press-and-hold switch which applies +28v
The audible tone (1 kHz) is used in the
On to panel lights DS1 thru DS6. When
modulator/demodulator for alarm signals,
the LIGHT switch is released, the panel
timing functions, and CW Key operation.