Main Receiver - Kenwood TS-990S Manual

The TS-990S has the overwhelmingly highest quality
receiver among the TS series.
The dual receivers facilitate reception on different bands.
The main receiver is the highest quality receiver among the TS-900 series,
thanks to its down-conversion configuration, newly developed mixer,
and five types of roofing filters. The highest quality transceiver shows its true
metal in contests, fierce pile-ups and high-intensity signals.
The TS-990S will surely satisfy any real DX'er.

Main Receiver

6
We have achieved a down-conversion format for all amateur bands
A key point in tapping maximum performance from the 1st mixer
in actual operation (say, CW operation) is to prevent the outflow of
unnecessary signals, other than the target signal, from the mixer to
the subsequent stage. This is because it can tap the maximum per-
formance of the digital IF filter using the DSP in the final IF stage.
The TS-990S main receiver employs a 1st IF frequency 8.248 MHz
down-conversion format. It achieves superior close-in dynamic range
unattainable through conventional up-conversion formats. Even if
the interference is a close-in frequency, the receiver maintains a
relatively flat dynamic range, which you can tune without losing your
target signal.
The horizontal axis shows separation of the target signal by interfering signal frequencies (two waves). At a frequency of 10 kHz,
interference 1 refers to reception frequency + 10 kHz, and interference 2 refers to reception frequency + 20 kHz.
The newly developed mixer contributes to achieving +40 dBm IP3
In place of the Double Balanced Mixer, which uses the J-FET, we have
installed the newly developed Double Balanced Grounded Switch Type
in the 1st mixer circuit, which is the heart of the main receiver.
The transceiver is also equipped with a pre selector function (works
on HF amateur band) that varies its tuning frequency in tandem with
the receiver frequency. It effectively dampens interference from strong
signals that cannot be minimized through bandpass filters on dedicated
amateur bands. Furthermore, we have achieved a +40 dBm class of
third-order intercept point for the signal path of the 1st mixer, based on
select circuits and components, employing large core toroidal coils for
protecting against distortion from large input signals, as well as using
relays for the signal switching.
0
-20
-40
-60
-80
-100
0.0
Amateur band RF BPF Pre Selector feature
Comparison
3rd order Intercept Point characteristics
50.00
40.00
30.00
20.00
10.00
0.00
-10.00
TS-990S
Our old model
-20.00
1 10
Interfering wave separation [kHz]
frx=14.2 MHz,PRE AMP OFF,BW 500 Hz,MODE CW
RF BPF
ATT
0/6/12/18 dB
Pre Selector 160m BAND
1.0 2.0 3.0 4.0 5.0
Frequency (Hz)
Transformer feedback RF Amp
100
through
Pre Selector