Section 7. Circuit Description; Block Diagram; Units - Kenwood TS-930S Instruction Manual

SECTION 7. CIRCUIT DESCRIPTION
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7.1 BLOCK DIAGRAM
The TS-930S block diagram is shown on page 39.
7.1-1 General
The TS-930S combines a quadruple conversion
superheterodyne receiver with a triple conversion transmit-
ter (double conversion in CW mode) using a filter-type SSB
generator. Intermediate frequencies are 44.93 MHz,
8.83 MHz, 455 kHz, and 100 kHz. The 100 kHz IF is us-
ed only in receive. Local oscillators incorporated include a
VCO (voltage controlled oscillator) controlled by the PLL, a
HET (heterodyne) oscillator (36.1 MHz), CAR 1 oscillator
(8.83 MHz), and CAR 2 oscillator (8.375 MHz). Both the
transmitter and receiver use these local oscillators. The
CAR 3 and CAR 4 oscillators permit CW pitch change, and
are used only by the receiver.
In the receiver mixer section, first and second mixers are
balanced, using two junction FET's (2SK125) each. The
third and fourth mixers use dual gate MOS FET's (3SK73).
In the transmitter, all mixers (first, second and third) are
balanced, using 3SK73, FET's.
Many accessory circuits are included. Adding to a monitor,
VOX, RF speech processor and etc., which were incor-
porated in earlier models, new features such as a new
Noise Blanker (NB2), automatic SWR meter, and Full
Break-in capability are now incorporated.
7.1-2 Transmitter
From the microphone, audio signal comes to the Signal unit
X57-1000-00 microphone amplifiers 0147, 146, 82, 83,
84, and to the balanced modulator D140 which converts
this signal to a DSB (double sideband) 455 kHz signal. This
signal passes a buffer amplifier Q87 and comes to a
ceramic filter CF1 which converts this to an SSB (single
sideband) signal. The first transmission mixer Q68, 69
then mixes the signal with CAR 2 (frequency 8.375 MHz),
converting the signal frequency to 8.83 MHz. The
resulting SSB signal passes a monolithic crystal filter (MCF
XF1) and enters the second transmission mixer Q55; 56
which converts the signal frequency to 44.93 MHz by mix-
ing with the HET signal (frequency 36.1 MHz). Then the
third transmission mixer 042, 43 mixes the signal with the
VCO (frequency 45.08-74.93 MHz), converting the signal
frequency to the final transmission frequency. This signal
passes through a transmission band-pass filter
(1.8-30 MHz) and, after being amplified by 041, 40, 39,
goes to the Final unit X56-1430-00. This unit amplifies
signal power (Q1~5). Finally, the Low-pass filter unit
X51-1280-00 removes spurious components from the
34
signal. The resulting signal is supplied to the antenna,
either directly, or through the optional Auto antenna tuner
(X57-1010-00).
7.1-3 Receiver
Signal from the antenna goes to the Signal unit and passes
one of nine band-pass filters. The RF unit X44-1490-00
amplifies (Q1) and mixes (Q2) the signal with the VCO fre-
quency, converting the signal to the first IF frequency
(44.93 MHz). The signal passes the post amplifier Q3, 4
and returns to the Signal unit where it passes a band-pass
filter composed of two MCFs (XF1, 2). The signal then
goes to the second reception mixer Q62, 63 which mixes
the signal with the HET frequency, generating the second
IF signal (8.83 MHz). The signal then passes the noise
blanker gate (D82, 84 ~ 86) and MCF XF1 and goes to the
third reception mixer Q65, 66 which generates the third IF
signal (455 kHz) by mixing with CAR 2 (frequency
8.375 MHz). This third IF signal is amplified by Q67 and
passes through ceramic filter CF1 and, after being
amplified by 0128, enters the fourth receiver mixer Q129
which generates the fourth IF signal (100 kHz). This signal
passes the notch filter (tuned by D217), a final IF amplifier
Q130, and then it is demodulated (D238~241). In AM
mode, the AM demodulator (D209, 219) operates. In all
other modes, the ring demodulator works. The AF
amplifiers Q160, 159 and IC3 drive the speaker.
7.2 UNITS
The TS-930S major units include the Signal unit, RF unit,
PLL unit, Digital unit, Final unit, Low-pass filter unit, Power
unit, and Switch unit.
7.2-1 Signal unit (X57-1000-11)
This unit includes most of the transmission/reception signal
circuits, which control signal circuits, local oscillators, and
accessory circuits. :
Optional crystal filters are installed on this unit. They plug-
in, and may be installed much easier than with conven-
tional models.
7.2-2 RF unit (X44-1490-00)
The mixer section of the receiver centers in this unit. Using
six junction FET's (2SK125), dynamic range is as high as
100 dB (using a 500 Hz [optional] filter).
7.2-3 PLL unit (X50-1880-00)
This includes three phase-locked loops to achieve digital
VFO operation in 10 Hz steps. The reference signal
oscillator is easily accessible from outside the case for
adjustment.
7.2-4 Digital unit (X54-1670-00)
A 1-chip microprocessor is the heart of this unit. Most