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Outline of Each Unit
1. TX Unit:
Part of the output power of the transceiver is detected at J101, so that the
carrier controlled solid-state switching circuit turns ON/OFF IC201
(NJM2072D) and Q202 (2SC1959Y), activating the TX/RX change-over
relay.
The RF signal inputted from J101 is amplified from 10W to 80W through
DRIVER AMP Q1 (MRF247), and further amplified to the designed power of
250W to330W through MAIN AMP Q1• ` Q5 (MRF247 x4). RF input level can
be selected to 10W, 25W or 50W by the POWER LEVEL SELECT SWITCH
SW1.
At the 10W input, the RF signal is directly connected to DRIVER AMP so that
the maximum gain can be attained.
At the 25W input, the RF signal goes through ATT1 (3dB) to be attenuated for
a proper input level, and is then fed into DRIVER AMP. At the point of either
10W or 25W, the output power can be reduced approx. half by using the
POWER LEVEL SELECT SWITCH.
At the 50W input, RL4 becomes activated to have DRIVE AMP by-passed so
that the RF signal directly drives MAIN AMP to the power of 300W. The
maximum current at the 300W output is approx. 36A where the heat
dissipation is designed to be held as low as possible.
The base bias of each of Q2 through Q5 is controlled by Q7 (2SC1173Y).
The combined power of 250W to 300W is fed through LPF and then sent out
through J102.
A multimeter is incorporated into the HL-350V
working conditions. By switching the Meter Switch, W (RF OUT: Output
Power), SWR (Standing Wave Ratio), or VCC (Power Line Voltage) can be
monitored.
Wattage and SWR are detected by a directional coupler.
SWR can be directly read out with the meter at or above a certain output
power (above 50W) as a result of the use of Divider IC203 (NJM4200D). The
divider is stably fed with +5V from three-terminal Regulator IC205
(NJM78L05A), and -5V from DC-DC Converter IC202 (ICL7660CPA).
to exactly take hold of the
DX
15
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