Circuit Description; Block Diagram; Unitized Circuits - Kenwood TS-700A Operating Manual

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5-1. Block Diagram
The circuit block diagram of TS-700A is shown in Fig.
15. Solid-state parts used in this model are: 71 transistors,
17 FET's, 6 IC's and 137 diodes. Circuits are divided into in-
dividual units according to the operating systems and all un-
its, with the exception of band pass filters (BPF), are wired
and built on printed-circuit boards.
The receiver section operates as a single
superheterodyne receiver in SSB mode and a double
superheterodyne receiver in FM mode. The transmitter sec-
tion is more versatile- it is a single conversion type and
operates as a filter type unit in SSB mode, a unit with direct
modulator using a variable reactance frequency shift ele-
ment in FM mode, a unit of low power modulation system in
AM, and as a unit of block bias keying system in CW mode.
Crystal Oscillator Frequencies
Carrier unit... USB 10.6985 MHz
LSB 10.7015 MHz
AM, CW 10.7006 MHz
Generator unit.............. FM 10.700 MHz
IBTSUBIE orseteraacaseresenes 144 125.100 MHz
145 126.100 MHz
146 127.100 MHz
147 128.100 MHz
5-2. Unitized Circuits
(1) Carrier Unit (X50-1160-00)
This unit produces a carrier frequency for the generator
unit during transmission but acts as a BFO for ring detection
during reception. It is a two-transistor circuit with oscillator
crystals and diodes. The diodes are for selecting the USB,
LSB or CW crystal, depending on the mode of operation.
(2) Generator Unit (X52-1080-21)
The single-side-band (SSB) signal for transmission
originates in this unit. Major components are a microphone
amplifier, a two-transistor audio frequency amplifier, a ring
modulator composed of 4 diodes, and a buffer. Other
devices are: a low power modulator circuit for AM, a
variable reactance frequency shift modulator for FM, a ring
detector for SSB reception, an IF circuit for SSB, AM and
CW, and an AM signal detector.
During SSB operation, this unit generates a double-
side-band (DSB) signals- this signal is injected into the
crystal filter and comes out as an SSB signal. During CW
operation, the ring modulator is forced into unbalanced con-
dition by biasing with a DC voltage and, in the unbalanced
condition, produces the carrier.
(3) FM IF Unit (X48-1140-20)
During reception, the input signal to this unit comes
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SECTION 5. CIRCUIT DESCRIPTION |
(4) MIX Unit (X48-1130-21)
(5) FINAL Unit (X56-1140-01)
(6) BPF Unit (X51-1090-21)
(7) MARKER Unit (X50-1280-00)
(8) RX-NB Unit (X55-1120-00)
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