TS-440S
CIRCUIT DESCRIPTION
OSB by IC4 goes through the SS B transmit switching diodes
0 1 7 and 0 1 8, filter switching diodes 0 1 4 and
O
1 2, and SSB
ceramic filter CF 1 , to obtain the SS B sig nal. The SSB sig nal
then goes through the transmit switching diode 036 and is
fed into the transmit first mixer, IC6, where the SS B sig nal
is mixed with the output from the 8 . 37 5 MHz oscillator in
the IF u nit, and converted to 8 . 8 3 MHz . In CW or FM mode,
the carrier sig nal from the PLL unit does not go through IC 5
B M or the 4 5 5 kHz filter. These carrie r sig n als a re applied
to IC6 via switching diodes 0 5 3 and 054. The output sig nal
from IC6 goes through the MCF to remove spurious compo
nents, and is amplified by the IF amplifier 046 ( 3S K73) and
sent to the RF u nit. 046 provid es ALC control and CW
keying .
I n the tra nsmitter second mixer, consisting of
O
1 1 and
O
1 2,
(3SK 1 2 2), the 8 . 83 MHz transmit IF sig nal input to the RF
u nit is mixed with HET oscillator sig nal ( 36 . 2 2 MHz) from
the PLL unit and converted to 4 5 . 0 5 MHz signals . The 4 5 . 0 5
MHz sig nal g o e s through D 2 3 and the M C F t o remove any
spurious components . The 45.05 MHz sig nal then goes
through D 27 and is supplied to the transmit third mixer cone
sisting of 0 1 3 and 0 1 4 (3SK 1 22). In the third mixer the sig
n al is mixed with VC O sig nal (02 1 to 024) amplified by 0 1 2
( 2SC 2668) and converted to the required transmit frequen
cy ( 1 . 8 to 29. 7 MHz) . The sig nal from the third mixer goes
through the low pass filters C 1 56, C 1 58, C 1 59, and L 89,
and is amplified by the wide band amplifier Q 1 5 (2SC2 570).
The signal then goes through the wide band transformer T 1 9
and low pass filters C 1 64, C 1 6 5, and L90, and is further am
plified by wid e band amplifier 0 1 6 ( 2S C 2 5 38). The sig nal
from the 0 1 6 goes through the output transformer T20 and
is used as the d rive output.
In FM mode, the PLL VC O is directly mod ulated . The audio
sig nal from IF u nit IC4 (UPC 1 1 58HZ) is fed into the RF u nit
via the FMI pin . In the RF u nit, the audio sig nal is amplified
by 036 ( 2SC 2459) a n d 037 (2SC 2603), and g oes through
the limiter circuit consisting of 038 (UPC 4 5 5 8C) and low
pass filter circuit, and is sent to the PLL u nit via the FMD
pin . In the PLL u nit, the 36 . 2 2 MHz VC O is mod ulated . 039
(2SC 2603) is a switching circuit to prevent the modulated
sig nals from being emitted from the PLL unit in a mode other
tha n FM.
For "S"
model radios the output from the R F unit is
amplified to a 100 W power level by 01 (2SC207 5 ), 02
and 03 (2SC2509), and 04 and 05 (2SC28 79) in the
final unit. The 1 00 W output goes through the LPFs which
differ by bands, and is sent as output to the antenna via the
AT unit and transmit/receive switching relay. SWR and
ALC detection is performed at the output of the LPFs
.
1
)
Antenna tuner
The a ntenna tuner operates when the A UTO/THRU switch
is in the AUTO position a n d the AT TU N E switch is ON. The
antenna tuner is driven in the CW mode and power is reduced
to 50 W by the microcomputer regardless of the mode select
ed before the AT TUN E switch was turned O N . The range
of operating freq uencies is d etermined by a microcomputer
prog ram, and is from 3 . 5 MHz to 30 MHz .
•
AT u n it o peration
Power transmitted by the final u nit passes through the cur
rent and voltage detecting transforme rs L 1 and L 2 using
toroidal cores . Current and voltage components detected
·
by the transformers a re supplied to pin s 9 and 1 3 of IC 2
for wave sha ping and their phases a re compared by IC 3
H0 1 0 1 3 1 . The output from pin 3 of IC 3 depends upon
the phase of the voltage and cu rrent w aveforms applied
to IC 3 . The sig nal from IC 3 pin 3 is sent to pins 1 0 and
1 5 of buffer IC IC 3 HD 1 0 1 2 5 . Output from pins 1 2 and
1 3 of IC 3 goes through level shift Zener diodes D 5 and
D6 to control the input circuit of motor d rive IC IC 5
BA6 1 09U2 . The output sig nal is used to d rive motor M 1
to adjust the varia ble capacito r VC 1 s o that the phase
difference between voltage and current components is
reduced .
The cu rrent and voltage components output from the cur
rent and voltage detecting transforme rs is also supplied
to the voltage comparato r IC 1 NJM29030. The compa
rator output is used by motor d rive IC IC6 BA6 1 09U2 to
d rive motor M2 to adjust variable capacitor VC 2 so that
the amplitude difference is reduced . That is, the phase con
trol varia ble capacitor VC 1 is controlled so that the cur
rent is in phase with the voltage and the voltage control
varia ble capacitor VC 2 is controlled so that the amou nt
of amplitude difference between the cu rrent and voltage
is reduced (SWR 1 , a n SWR of 1 to 1 , is obtained when
the cu rrent and voltage a re in phase and the amo u nt of
amplitude difference is 0) . VC 1 and VC 2 a re d esig ned to
operate independently of each other, but since phase
difference affects the amou nt of amplitude difference and
vice versa, VC 1 and VC 2 will normally rotate together .
Forward and reflected waves detected by the filter u nit a re
converted to SWR control sig n als in the SWR a rithmetic cir
cuit in the control unit and a re sent to the ISW pin of the
AT u nit. Since the SWR control sig n als are c u rrent wave
forms, the sig n als are converted from I to V waveforms by
IC 8 (b/4) in the AT
unit and
to obtain the corresponding vol
tage mod e SWR sig nals are generated . The SWR sig nals are
then fed into the SWR compa rato r IC 8 (C /4). The reference
voltage pin 9 of the IC 8 (C /4) is supplied with a voltage cor
responding to an SWR of 1 . 2 5 to 1 via a potentiometer .
Therefore, w h e n the actual SWR value exceeds 1 . 2 5, pin 8
of SWR comparator IC 8 (C /4) is H, so the motor d rive vol
tage control transistor 05 turns on a n d the collector of 04
is supplied with voltage from pin 1 4S. The voltag e is also
used to turn the tuning LED o n . The inverted input pin of IC 8
(d/4) is supplied with triangular waves generated by IC7, and
its non-inverted input pin is supplied with the a bove SWR vol
tage sig n als . As a result, as SWR lowers, IC 8 (d/4) outputs
1 1
