Filter
Top Products
TS-590S CONTENTS 11
2 TRANSMISSION
The tradition of high quality audio technology that users rely on Kenwood to deliver is produced by
combining analog and digital technologies that Kenwood has nurtured thus far. The DSP controls
modulation and determines the sound quality and analog circuits convey and amplify the signal
cleanly.
The first IF transmit signal that is output at 24 kHz from the DSP and the DA converter is converted to
10.695 MHz in a dedicated IC for the mixer. The second IF signal at 10.695 MHz passes an IF filter
of 6 kHz bandwidth at which undesired frequency components outside the pass bandwidth are
attenuated before the signal is amplified. Then, the second IF signal passes to the ALC circuit that
controls the output power to a stable level. After that, the signal goes through the gain control circuit
that corrects the minutely small differences in gain from band to band, and the signal enters the mixer
that is commonly used in TX and RX, and is converted to the third IF of 73.095 MHz. The signal
passes the gain control circuit that adjusts the signal to the necessary gain level according to the
specified power level. Then, the signal passes the filter that eliminates spurious components before
going into the mixer circuit that converts the signal to the desired transmit frequency. Also, delicate
gain control is done, such as decreasing the gain of the amplifier while the key is not depressed in
CW mode. By means of these processes, a high-quality transmit signal with low noise can be
acquired. The signal converted to the desired transmit frequency passes the BPF for removing
spurious signals to prevent from generating interfering signals outside of the transmit bandwidth, and
is amplified to a prescribed level before being sent to the final circuit. The drive signal produced here
can be extracted from the DRV terminal. (While the output from DRV is selected.)
The final amplifier of the TS-590S is a push-pull amplifier using two pieces of RD100HHF1 MOSFET
from Mitsubishi Electric Semiconductor (Pch 176.5 W). The drive amplifier also uses an
RD100HHF1 MOSFET and the pre-drive amplifier employs an RD06HHF1 MOSFET and they,
despite being 13.8V final circuits, amplify the signal reasonably in a stable and continuous manner
with low distortion. Figure 2-1 shows the graph of IMD characteristics and Figure 2-2 shows the
graph of harmonic spurious characteristics. Superior distortion characteristics and clean signals are
acquired in this way.
2.1 Kenwood Traditional Transmitting Circuitry
2.1.1 IF Circuits
2.1.2 FET Final Circuit