Optimization Of Gain Distribution; Deflection Of The S Meter Needle - Kenwood TS-890S In-Depth Manual

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,
approximately +12 dB is the standard configuration in the amateur bands up to the 21 MHz band and approximately +20
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"
S-meter 表⽰
S1 3 dot
S3 11 dot
S5 19 dot
S7 27 dot
S9 35 dot
S9+20 48 dot
S9+40 59 dot
S9+60 70 dot
8
Table 2 S Meter Levels (Reference)
0.03 M ~ 21.5 MHz
PREAMP 1
All Mode
Type 1 Type 2
-107.0 dBm -121.0 dBm
-100.5 dBm -109.0 dBm
-94.0 dBm -97.0 dBm
-87.5 dBm -85.0 dBm
-81.0 dBm -73.0 dBm
-61.0 dBm -53.0 dBm
-41.0 dBm -33.0 dBm
-21.0 dBm -13.0 dBm
21.5 M ～ 60 MHz ( ～ 74.8 MHz*)
*European model only
PREAMP 2
All Mode, FM Normal
Type 1 Type 2
-114.0 dBm -141.0 dBm
-107.5 dBm -129.0 dBm
-101.0 dBm -117.0 dBm
-94.5 dBm -105.0 dBm
-88.0 dBm -93.0 dBm
-68.0 dBm -73.0 dBm
-48.0 dBm -53.0 dBm
-28.0 dBm -33.0 dBm
FM High
Type 1
-116.0 dBm
-113.8 dBm
-111.3 dBm
-108.7 dBm
-106.2 dBm
-102.0 dBm
-98.5 dBm
-95.0 dBm