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TS-440S
CIRCUIT DESCRIPTIO N
waves changing from continuous waves to relatively low duty pulses . Q1 is driven by this voltage waveform to control Q2 , which is connected to the collector of Q4 in series and mo- tor drive voltage is generated .
If the motor turns too fast, the SWR value will be smalle r than the motor stop value because of the inertia of the mo- tor . As a result, the motor will continue to operate even if
TUNE STO P
ADJ IC8 c/4
the motor stop signal is sent and the SWR value will con- tinue to be greater than the motor stop value, causing th e motor stop signal to turn off . That is, the motor will not sto p and it will be difficult to obtain a match . If the motor spee d is too slow, it will take a long time to satisfy a matching con - dition . The
Q 5
Triangular wov e generator
Fig . 7 Antenna tuner circuit
The antenna coupler is a T type . Six relays RL100 to RL10 5 are used to change taps within the range 3 .5 MHz to 30 MHz .
2) Cooling fan circuit
The final unit contains the
When temperature on the surface of Q4 goes down to 45°C , the cooling fan turns off .
Comparato r output
Q9 B
V
/45° /50° | 0° Bo° | Temperature ° C |
FAN OFF FAN ON | Thermal | Therma l |
| protection OFF protection ON |
Fig . 8 temperature protection operatio n
•Final temperature protection circuit
When the temperature of the final transistor Q4 rises u p to approx . 80°C, the temperature protection comparato r Q9A turns on (H level), Q1 in the filter unit also turns on , and a minus DC voltage is supplied to the ALC line, reduc - ing the transmitter output to zero . (The
•SWR protection circuit
When antenna VSWR is bad, or the reflected wave is to o large, because the auto antenna is tuning for example, L4 2 and L43 detect the state and its output is rectified . Th e rectified signal is then amplified by Q2 to control the AL C voltage so that drive power is reduced . As a result, loa d on the final unit is reduced .
•SWR automatic arithmetic circuit
The
IC5 contains a level shift/meter amplifier and an auto tune r
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