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|  TM
11-5820-919-40-1
(2-30 MHz and 152-180 MHz). The rf
been previously amplified at amplifier
mixing product is routed through ener-
U1.) This results in a 75-MHz mixing
gized contacts 8 and 7 of relay K1 Lo
product (either 75 plus 65 MHz or 75
the 2-30 MHz amplifier Q1 thru Q3, T1
plus 85 MHz).
The 75-MHz mixing product
thru T6 where it is boosted to 0.25
is routed through energized contacts 8-7
of relay K1, through amplifier Q1, T3
watt.
The frequency component above
and back through energized contacts 3-2.
30 MHz is not amplified. The +12.5v
Transmit from the third converter powers
The 75-MHz mixing product is routed to
bandpass filter FL1.
this amplifier.
In receive mode,
The rf mixing product
the 75-MHz if. passes through deener-
goes through energized contacts 3 and 2
gized contacts (2-4-7) of relay K1,
of relay K1 to the output jack, J3. In
receive operation, the 2-30 MHz rf is
through amplifier Q1 and back through
routed through contacts 2, 4, 6 and 8 of
contacts 3-6-8.
The 75-MHz if. mixes
relay K1 to mixer U4.
The 2-30 MHz rf
with the 70/80-MHz LO at mixer U4.
mixes with the 77-105. MHz LO to produce
The 5-MHz mixing product goes through
a 75-MHz mixing product.
amplifier Q2, T4 and isolation trans-
The FET Q3 and amplifier U3
former T5.
control the gain of the 5-MHz mixing
HARMONIC
FILTER
The control signal is applied
product.
from the agc generator U3 in the third
General Transmit Operation.
converter.
Finally the 5-MHz mixing
The harmonic filter suppresses trans-
mitter harmonics and noise levels out-
product is routed to pin 29 to the
sideband filter FL2.
side of the selected frequency band.
Bandpass Filter Selection.
The filter
2-97.
Bandpass Filter FL1.
functions identically in receive and
The selection of one of six bandpass fil-
ters, FL1 thru FL6, is controlled by the
transmit operation. The filter rejects
frequencies other than 75 MHz,
15 kHz.
filter select Band signals from the
control panel.
The filter select signal
In transmit
2-98.
First Converter.
(grid) is applied directly to the relays
of the selected bandpass filter to
operation, relay K1 is energized by the
+28v Xmt Enable and by the Keyline
provide a return path for the relay
ground signal.
The following chart lists the
The 75-MHz if. goes to
filter select Band signal and the filter
mixer U2 where it mixes with the 77-105
selected by the signal.
For example,
MHz LO. (The 77-105 MHz LO has been
the 2-3 MHz Band Select signal selects
previously amplified at amplifier U1.)
FL6 between 2,000 kHz and 2,999 kHz.
This results in the rf mixing product
Selected
Filter
Filter
Select
Signal
20-30
MHz
Band
FL1
10-20 MHz Band
FL2
FL3
8-12 MHz Band
FL4
5-8 MHz Band
FL5
3-5 MHz Band
FL6
2-3 MHz Band
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