THEORY OF OPERATION
While reading this section, refer to Figure 5-1, the Functions
and
Chass~s lnterconne~t~ons diagram (fold-out from Page
-
323).
RECEIVER
Refer to the "Receiver Block Diagram," fold-out from Page
267.
The incoming signals
pas through the FilterIALC circuit
board to the Receiver Front End board if the sameantenna
is used for receiving and transmitting. If the separate
receiving antenna connection is used, the incoming signals
are applied directly to the Receiver Front End circuit board.
The incoming signal next passes through the appropriate
bandpass filter on the Receiver Front End circuit board, and
is then mixed with the signals from the VFO and the HFO
to
form the 3395
kHz
IF signal. Onesection of the RF Gain
control acts as a shunt to vary the level.
The IF signal is connected to the Carrier
GeneratorICrystal
Filter circuit board which contains a selective crystal filter
for
SSB,
and generates the USB, LSB, and
CW
BFO signals.
Solid-state switching
is
used for mode selection and also to
select the proper filter if the optional
CW
crystal filter is
installed.
The 3395
kHz
IF signal is fed to' the Receiver IFIAudio
circuit board where
it
is amplified, detected, and the audio
signal again amplified. The second half of the RF Gain
control varies the IF gain. AGC voltage is detected and
amplified on this
circu~t board. The circuit provides fast,
slow,
or off AGC action. The Smeter driver operates in
conjunction with the AGC voltage. Audio inputs, outputs
and controls are connected to this circuit board.
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