Kenwood TS-440S Service Manual page 12

TS-440S
waves changing from continuous waves t o rel atively l o w d uty
p u l s e s . 0 1 is d riven by this voltage waveform to control 02,
which is c o n ne cted to the c o l l ector of 04 in s e ries and mo­
tor d rive voltage is g e n e rated .
If the motor t u r n s too fa st, the SWR v a l u e wil l be sma l l e r
tha n the mot o r stop v a l u e because o f the i n e rtia o f the mo­
t o r . As a resu lt, the moto r wil l contin u e to ope rate even if
SW o--- -- --1
I
+5V
The ante n n a c o u p l e r is a T typ e . Six rel ays RL 1 00 to RL 1 0 5
a re used to change taps within the range 3 . 5 MHz to 30 MHz.
2) Cooling fan circ u it
The fin a l u nit contains the temperatu re-s e n sitive the rmistor
TH 1 the rmal ly coupled with fin a l tran sistor 04 . When tem­
p erature on the s u rface of 04 reaches a p p rox. 5 0°C, the fan
sta rt compa rator 098 o p e rates (H leve l), c a u si n g 0 8 to turn
o n to o p e rate the f a n . D u ring op er atio n of the fan, tempera­
t u re p rotection compa rator 09A is at a L level, so the tem­
p e rature p rotection circ uit does n ot o p e rate .
When temperature on the s u rface of 04 goes down to 4 5°C,
the cooling f a n turns off .
Comporotor
o u t p u t
"L••
45• /5<:!' jro• B<:!'�
FAN OFF FAN ON
Fig . 8 tem pe rature prote ction o peration
12
CIRCUIT D ESCRI PTION
ICS
b/4
1-V Convertor
IC 7
Trlanoulor wove
venerator
Fig . 7 Ante n n a tun e r circuit
098 Q9 A
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I
'+' ,+.
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I
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___ .1_�
Temperature
OFF ON
Thermal
Thermal
protection protection
the motor stop sig n a l is s e nt a n d the SWR v a l u e will con­
tin u e to be g re ate r tha n the moto r stop value, c a u sing the
moto r stop sig n a l to t u r n off . That is, the motor will not stop
and it will be difficult to obtain a match . If the motor speed
is too s l ow, it will take a long time to satisfy a matching con­
ditio n . The TS -440 therefore controls the motor speed ac­
cording to cha nges in SWR.
14V
•
Final temperature protection circuit
Whe n the tempe ratu re of the fin a l transisto r 04 rises u p
t o a p p rox . 8 0°C, the temperature p rotection compa rator
09A turns o n (H l eve l), 0 1 in the filter u nit also turns on,
a n d a min u s DC voltage is s u p p lied to the ALC line, red u c­
ing the tran smitter output to ze ro . (The TS-440 does n ot
ret u r n to a receive state .) Whe n the temperature of the
fin a l transistor 04 f a l l s to a p p rox . 70°C, the p rotection
circuits turns off a l l owing the transmitter to operate again .
•
SWR protection c ircuit
When ante n n a V SWR is bad, o r the reflected wave is too
l a rge, beca use the auto antenna is tu ning for example, L42
a n d L43 d etect the state a n d its output is rectified . The
rectified sig n a l is the n amp lified by 0 2 to control the ALC
voltage so that d rive p o w e r is red u c e d . A s a resu lt, load
o n the fin a l u nit is red uced .
•
SWR a utomatic arith m etic c i rcuit
The TS -440 uses the automatic a rithmetic circuit in the
AT- 2 5 0 . The forward wave voltage
•c
wave voltag e VsR from the filter u nit a re fed into the a n a­
l o g a rithmetic circuit of the switch u nit, a n d used to set
the vo ltage level of IC 8 pin 2 ( 5 V + V sRIV S F). Output vol­
tage f rom the pin 2 is shifted by IC 5 to move the n e e d l e
in t h e S W R mete r .
I C 5 contains a level shift/mete r amplifier a n d a n a uto tuner
V-1 converto r . IC7 co ntains a squ a re wave g e n e rator and
a voltag e comp a rato r . IC 8 contains a n integ ration circ uit .
03 a n d 04 are used to switch forward a n d reflected wave
i n p ut sig n a l s a lternately .
#
AT TUN E LED
Motor drive vollove
Y
s F a n d reflected