8
02 RECEPTION CIRCUIT
Optimization Of Gain Distribution
The first mixer, which is the key block in the receiver, has a large conversion loss. Therefore, a pre-amplifier to improve
sensitivity is placed.
Pre-amplifier 1 is the standard behavior in a reception band below 21.5 MHz, and pre-amplifier 2 is the standard
behavior in a reception band of 21.5 MHz or larger, and depending on the radio wave status, OFF / PRE1 / PRE2 can be
switched by pressing the
[ANT/PRE]
key.
The attenuation outside the band is fully obtained by the roofing filters with good selectivity, thus even through the
analog AGC amplifier and high-gain IF amplifier in a later stage, undistorted IF signals are supplied as baseband signals
to the DSP.
Deflection of the S Meter Needle
The IARU (International Amateur Radio Union) standard scale requires -73 dBm for S9. However, concerning the S
meter needle deflection, on all of the KENWOOD transceivers, it is -81 dBm for S9 in the 14 MHz band while a pre-
amplifier is on. The TS-890S also provides the S meter needle deflection familiar to operators using a conventional
model.
Turning off the pre-amplifiers lowers the gain and the S meter needle deflection. For the gain change by a pre-amplifier,
approxi12 dB is the standard configuration in the amateur bands up to the 21 MHz band and approxi20
dB in the higher bands.
The “S Meter Levels” table shows the indicated levels of the S meter. (The S meter level is managed at S1, S9, or S9+60
dB in the 14 M /50 MHz band.)
In FM mode, the same deflection (Normal) as that in other mode is the default, and you can select the same high
sensitivity (High) as that configured for conventional models through Menu 0-07 “FM Mode S-meter Sensitivity”
Table 2 S Meter Levels (Reference)
S-meter 表⽰
0.03 M ~ 21.5 MHz
21.5 M ~ 60 MHz ( ~ 74.8 MHz*)
*European model only
PREAMP 1
PREAMP 2
All Mode
All Mode, FM Normal
FM High
Type 1
Type 2
Type 1
Type 2
Type 1
S1
3 dot
-107.0 dBm
-121.0 dBm
-114.0 dBm
-141.0 dBm
-116.0 dBm
S3
11 dot
-100.5 dBm
-109.0 dBm
-107.5 dBm
-129.0 dBm
-113.8 dBm
S5
19 dot
-94.0 dBm
-97.0 dBm
-101.0 dBm
-117.0 dBm
-111.3 dBm
S7
27 dot
-87.5 dBm
-85.0 dBm
-94.5 dBm
-105.0 dBm
-108.7 dBm
S9
35 dot
-81.0 dBm
-73.0 dBm
-88.0 dBm
-93.0 dBm
-106.2 dBm
S9+20
48 dot
-61.0 dBm
-53.0 dBm
-68.0 dBm
-73.0 dBm
-102.0 dBm
S9+40
59 dot
-41.0 dBm
-33.0 dBm
-48.0 dBm
-53.0 dBm
-98.5 dBm
S9+60
70 dot
-21.0 dBm
-13.0 dBm
-28.0 dBm
-33.0 dBm
-95.0 dBm