Author: Tworzenie stron internetowych
Kenwood TS-990 From LAMCO Barnsley
1. Down conversion employed for all Amateur Radio bands (main receiver)
The main receiver of the TS-990 employs down conversion for the first IF (8.248MHz) for all Amateur bands. This results in excellent dynamic range when adjacent unwanted signals are present – significantly better than what was possible with the up-conversion approach previously used. Even when the interfering signal is on an adjacent frequency, the TS-990 is able to maintain almost flat dynamic range characteristics, capturing just the target signal.
2. Newly developed mixer contributes to IP3 +40dBm performance (main receiver)
The first mixer circuit, at the heart of the main receiver, is equipped with a new double balanced grounded switch type mixer. In order to prevent distortion when there is a large input signal, the signal route up to the first mixer includes sophisticated circuitry with carefully selected components – such as large-core toroidal coils and relays for signal switching between bands – resulting in a third-order intercept point of +40dBm.
3. New narrow-band high-IP roofing filters help to remove adjacent interference (main receiver)
As well as employing down conversion for reception on all Amateur bands, the TS-990 is equipped with 5 high-IP roofing filters as standard. In addition to 500Hz and 270Hz filters, which provide the sort of narrow passband that is so important for CW (Morse code) operations, there is a 2.7kHz filter for SSB, as well as 6kHz and 15kHz filters suited for AM/FM use. These filters are selected automatically depending on the DSP’s final passband setting. Manual switching is also possible.
4. New VCO division-type first local oscillator divides high frequencies to ensure high C/N
The TS-990’s local oscillator features independent circuits optimized for different signals: VCO division type / DDS direct for the main receiver; DDS direct for the sub receiver; and conventional PLL for the transmitter. The newly developed VCO division-type approach adopted for the first local oscillator of the main receiver involves having the VCO oscillate at a frequency higher than the target frequency, and by dividing this frequency it is possible to generate a local oscillator signal with excellent C/N characteristics, almost as good as produced by a DDS direct circuit, and with low spurious emission equivalent to that of PLL. This reduces noise in the local oscillator and, thanks to the high C/N ratio, the target signal is not allowed to become buried in noise. The pure incoming signal can thus be shifted to a first IF.
5. 0.1ppm TCXO ensures both high stability and reduced power consumption
As a standard signal source, the TS-990 is equipped with a TCXO (temperature-compensated crystal oscillator) that has a frequency stability of ±0.1ppm. In addition to delivering high stability, it does not require a warm-up period like an OCXO (oven-controlled crystal oscillator), so it can start up rapidly as soon as power is applied. It also complies with the European Union’s Lot 6 standard for energy conservation, consuming less than 0.5W in standby mode. Input/output of a standard 10MHz signal is enabled.
6. Sub receiver down conversion*2 on main Amateur bands below 21MHz range
For its sub receiver, the TS-990 uses a more advanced version of the receiver found in the TS-590, which since it was launched has been acclaimed for its top-of-class RX performance. Of especial note is the fact that it uses front end circuitry that enables down conversion for the 5 major Amateur bands, so that despite being a “sub receiver” it has what it takes for full-fledged RX applications.
*2 When IF band is below 2.7kHz for 1.8/3.5/7/14/21MHz bands (SSB/CW/FSK/PSK).
7. Dedicated triple DSPs for main & sub receivers plus band scope