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Page Title:
Figure 18. 1-mc spectrum generator module A15, schematic diagram. |
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|  C10 to the selected crystal ((2) be-
Y11 (5.65 mc) will be selected
low), and the contacts of S1A to the
through contacts 8 and 11 of S1A;
emitter of Q2; this action com-
this action completes the regen-
pletes the regenerative circuit.
erative circuit to the emitter of
(2) Crystal selection is determined by
Q2. If the RT-505/PRC-25 is op-
the operating mode (received or
erating on a 50-kc channel (31.15
transmit) and by the frequency se-
mc, 74.25 mc, etc.), S1A will be
lected by the kc tuning control.
turned clockwise one position from
When the RT-505/PRC-25 is in the
that shown and crystal Y12 (5.60
receive mode, +10 volts is applied
mc) will be connected through con-
through normally closed contacts 4
tacts 8 and 9 of S1A; this action
and 6 of front-end relay K1 (fig.
completes the regenerative circuit
to the emitter of Q2.
and A10J1, and current-limiting
(3) When the RT-505/PRC-25 is in the
resistor R5 to the anode of CR1.
transmit mode, front-end relay K1
T h i s positive voltage forward
biases CR1; the diode conducts
and 6 open, and +10 volts is no
heavily and allows the regenerative
longer available for diode CR1. The
circuit to crystals Y11 and Y12 to
diode is now reverse-biased and
be completed. If the RT-505/PRC-
prevents the selection of crystal
25 is operating on a 100-kc channel
Y11 or Y12. Relay K1 contacts 4
(31.10 mc, 74.20 mc, etc), S1A will
and 7 are closed and apply+ 10 volts
be in the position shown and crystal
through pin K of connectors J12
29
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