Ten-Tec JUPITER - Page 81

Common-gate buffer, 035 and ТІ1 feed
this signal to FL3, a ceramic bandpass
filter, followed in tum by the Q33 and Q34
cascode amplifier. The IF signal proceeds
to the third mixer, D12 and D18 – D20,
via T12, which also feeds the amplified
AGC detector between 037 and 041.
The T (transmit) control voltage at R162
mutes the receiver during transmit times.
Following the third mixer, dual op-amp
ІЛІ and associated components apply а
combination of active and passive filtering
to condition the signal for circuitry on the
Logic board.
5.4.1.3. Transmitter Section
See Figures 4-5 and 4-6 for the transmitter
section schematic of JUPITER' RF
board. From its source on the Logic
board, the modulated TX_IN signal feeds
the 34 IF mixer at 018 where the 39 LO
converts the signal from its 13 kHz center
frequency to 454 kHz. #12 defines the
214 ТЕ passband and feeds 1719, the 2”
mixer. Тһе 274 LO causes frequency
translation to 45 MHz. Тһе monolithic
crystal filter, ЕЛ, and 032 filter and
amplify the 274 IF signal for the final
mixer, which uses the first LO to shift the
signal to the required amateur frequency.
Q25 and Q19 are broadband HF amplifiers
that develop input for the Power Amplifier
board. 023, Q24, and Q26 use the T
control signal to apply operating bias for
transmitting and to mute the amplifiers
during receive periods.
The two sections of 010 condition
forward and reflected power signals from
the Lowpass Filter board for use by the
Logic metering functions. R86 and R83
set the meter calibration Юг those
functions. The forward power signal and
the РА current signal combine in R231
(via 062 and D63) to produce input for
Ова This op amp and the low-pass
74269 Second Pprinting
JUPITER Model 538
30 August 2001
filtered buffer, Q30 and Q31, generate the
ALCFB (Automatic Level Control
Feedback) to 010 to perform transmitter
ALC. Ова also sums in a front panel
power control signal from the Logic board
to allow a range of RF power adjustments
below the factory set point.
The U8a output also drives a peak detector
(046, R203, and C222) and U8b which
supply a signal for the ALC indicator on
the front panel. The R (receive) control
voltage feeds Q44 to extinguish the ALC
indicator as soon as JUPITER switches to
receive. Тһе В voltage feeds a buffer
amplifier at Q21 and 028 to distribute that
control signal to the 81863 board. In
similar manner, Q22 and 028 buffer the Т
signal.
5.4.2, Logic Board - P/N 81889
Figure 4-9 is the overall schematic
diagram for the Logic board. Five
subordinate sheets (Figures 4-10 through
4-14) cover the detailed diagrams.
5.4.2.1. Power/Control Section
Figure 4-10 shows the circuitry of the
Power/Control section, comprised of a
voltage regulator to condition the RF
board 5 volt supply, networks to condition
the 10vrf distribution point, Ше RS232
integrated circuit level converter for the
Serial Interface connector on the rear
panel, and two distinct 13 volt paths.
13vpd is a power-down signal to the
CPU. 13vd supplies voltage to Q1, an
FET anti-pop switch on the Auxiliary
Audio Output section of the Logic board.
5.4.2.2. Audio ИО Section
Refer to Figure 4-11. Signal OUT_R
brings received audio from 019 on the
Codec section to the audio output
amplifier, 012 VOLUME V is a DC
volume control voltage from one channel
5-3