Kenwood TS-890S, Подробное руководство

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11
RECEPTION CIRCUIT 02
Auxiliary Circuits
Medium Wave Band Sensitivity Risers
Just as in past transceivers, the TS-890S has attenuators of approximately 20 dB for the medium wave band (522 kHz to
1.705 MHz) (as the factory default, the sensitivity is lowered by approximately 20 dB by the attenuators). In the medium
wave band, there are a number of strong radio waves and there may be medium wave band signal input that is excessive
for low-band antennas. The inserted attenuators are intended for clear reception with no distortion even if such strong
medium wave band signals are received. The signal can bypass the attenuator after switching the jumper pins on the
board so as to allow the sensitivity to increase.
The image “Jumper Pin Locations” is the image of the TX-RX unit board with the main band attenuator jumper pins
placed. Detach the TS-890S lower case to access the TX-RX unit. (Before detaching the lower case, be sure to first
detach the upper case. There is the danger of the cases being damaged.)
Table 3 Medium Wave Band ATTs
NORM（ATT: 20 dB） DX:Thru
CN 302 CN 301
Fig. 12 Jumper Pin Locations
The jumper pins are placed in the “NORM” position at shipment. Switching the jumper pins to “DX” bypasses the
attenuators and raises the medium wave band sensitivity by approximately 20 dB.
Fig. 13 Medium Wave Bandpass Filter Characteristics