Kenwood TK-80, Service Manual

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TK-80
15
Item Rating
Center frequency (fo) 73.045MHz
Pass bandwidth ± 7.5kHz or more at 3dB
Attenuation bandwidth ± 30kHz or less at 20dB
Ripple 1dB or less
Insertion loss 2dB or less
Guaranteed attenuation 40dB or more at fo–910kHz
Terminal impedance 2k
Ω±
10% // L type
Temperature range –30 ° C~+70 ° C
Table 2 MCF (XF1) (L71-0432-05)
Item Rating
Nominal center frequency (fo) 10.695MHz
Pass bandwidth 6kHz or more at 6dB
Attenuation bandwidth 40kHz or less at 60dB
Ripple 2dB or less
Insertion loss 3dB or less
Guaranteed attenuation 60dB or more within fo
±
1MHz
Terminal impedance 1.2k
Ω±
10% // 6pF
±
10%
Table 3 MCF (XF3) (L71-0433-15)
Item Rating
Nominal center frequency (fo) 10.695MHz
Center frequency deviation Within ± 200Hz at 6dB
Pass bandwidth and Width 2.75kHz or more at 6dB
Attenuation bandwidth ± 2.2kHz or less at 20dB
± 3.1kHz or less at 60dB
Ripple 2dB or less
Insertion loss 6dB or less
Terminal impedance 1.2k Ω± 5% // 8pF ± 10%
Temperature range –10
°
C~+60
°
C
Table 4 MCF (L71-0457-05) KIF-1: SSB WIDE (Option)
Item Rating
Nominal center frequency (fo) 10.695MHz
Center frequency deviation Within
±
200Hz at 6dB
Pass bandwidth and 2.2kHz or more at 6dB
Attenuation bandwidth
±
1.5kHz or less at 20dB
±
2.4kHz or less at 60dB
Ripple 2dB or less
Insertion loss 5dB or less
Guaranteed attenuation 60dB or more within fo
±
40kHz
Terminal impedance 1.2k
Ω±
5% // 6pF
±
5%
Table 5 MCF (XF2) (L71-0249-05)
Item Rating
Nominal center frequency (fo) 10.695MHz
Center frequency deviation Within ± 80Hz (25 ° C, 6dB)
Pass bandwidth 500Hz or more (6dB)
Insertion loss 5dB
±
2dB
Terminal impedance 1200 Ω // 6pF
Table 6 MCF (L71-0283-15) YK-107C: CW (Option)
4. Transmitter Circuit Configuration
The audio signal from the microphone enters CN 12 of the
TX-RX unit. The signal then goes to IC9, the microphone
amplifier. After amplifying part of IC9’s output at Q54, it is
detected by D59 and applied to the ALC terminal of IC9. The
signal gain is properly adjusted by the D/A converter IC13 and
passes through analog switch IC8, is amplified by Q50. The
amplified signal is balance-modulated with the CAR signal
(10.695MHz) input from CN9 by IC4 passed through Q51,
and sent to the crystal filter passing through the filter, is am-
plified by Q24. The signal is CAR level adjusted by the D48
pin diode, and input to the mixer.
The 62.35MHz LO2 signal from the PLL unit is input from
CN3 of the TX-RX unit, and mixed with the 10.695MHz signal
which CAR level adjusted amplified by Q25 and Q26 to pro-
duce a 73.045MHz signal. The LO1 signal from the PLL unit
is input from CN2 of the TX-RX unit, and mixed with the
73.045MHz signal passes through LC three-stage filter by
Q27 and Q28 to generate the desired signal. The signal
passes through the band-pass filter and is amplified by Q29
to produce the drive output, which goes to the final unit from
CN19.
The signal is amplified to about 100W by Q1, Q2, Q3 and
Q5, Q6. Harmonic components are attenuated by the filter
unit and the signal is output from the antenna connector.
In AM mode, the signal is generated by unbalancing the
carrier of SSB balance modulator IC4.
In CW mode, the signal is input to IC5 of the control unit.
The sidetone monitor signal is generated by IC5, and ampli-
fied by audio amplifier Q79 and IC7, and output from the
speaker. The CW control signal is output from IC5 of the
control unit, and input to CN14 of the TX-RX unit to switch
Q25 and Q26 and generate the CW signal.
4-1. ALC circuit
The forward wave voltage detected in the final unit passes
through CN15 in the TX-RX unit, its level is potential dividing
and it is applied to the differential amplifier comprising Q60
and Q61. When VSF is applied to the base of Q60, the emit-
ter voltage of Q60 and Q61 increases and the current flowing
through the base of Q61 decreases; thus the collector volt-
age rises. When this voltage exceeds the emitter voltage of
Q62 (about 1.8V) plus V
BE
(about 0.6V), the current flows
through the base of Q62 and the collector voltage drops.
ALC time constants C and R are connected to this collector.
The collector voltage change is shifted by Q64 and D68
(3.6V), and matched with the voltage for keying by Q65 and
D69 to generate the ALC voltage. This ALC voltage activates
ALC by lowering the second gate voltage of Q24 of the TX-RX
unit (Fig. 7).
CIRCUIT DESCRIPTION