Kenwood manual Comes equipped with ±0.1 ppm TCXO, HF/50MHz TRANSCEIVER TS-990S, Main receiver

HF/50MHz TRANSCEIVER TS-990S Main receiver

The newly developed narrow-band High-IP roofing filters show their true value by cutting adjacent unwanted signals

High C/N levels are realized by dividing high frequencies using the newly developed VCO frequency division 1st local oscillator

The transceiver uses the down-conversion method on all amateur bands, and features five types of High-IP roofing filter. Narrow bandpass widths selectable are 500 Hz and 270 Hz for CW opera- tion, 2.7 kHz for SSB and 6 kHz and 15 kHz, which are suitable for AM/FM. These filters are automatically selected in tandem with DSP-based settings. Of course, manual switching is possible as well.

The TS-990S Local Oscillator Circuit is an indepen- dent configuration that combines the main receiver and VCO Frequency Division/DDS, the sub-receiver, DDS, transmitter and conventional PLL, with the targeted signal system. The newly developed VCO frequency division format is used for the 1st local oscillator of the main receiver. The device achieves favorable C/N characteristics that rival the DDS direct format, and relatively spurious-free local oscillation signals that are characteristic of the PLL format, by oscillating and dividing the VCO at higher frequencies

TS-990S MAIN Local OSC C/N

	0	14.1 MHz
	-10
		1.83 MHz
	-20
	-30
[dBc/Hz]	-40
	-50
	-60
	-70
Noise	-80
	-90
	-100
Phase
	-110
	-120
	-130
	-140
	-150
	-160

Roofing

Filters

270 Hz

TS-990S MAIN BAND FRONT-END

CH1 B/R log MAG	10 dB/ REF 0 DB
CH2 B/R log MAG	10 dB/ REF 0 DB

than the intended frequency. It is possible to convert it to 1st IF in a pure state without leaking the target signal as noise by reducing static noise from the local oscillator and increasing the C/N ratio.

100 1,000 10,000 100,000

Offset Frequency [Hz]

Main receiver 1st Local Oscillator C/N Main receiver characteristic example (20m/160m)

				500 Hz
	1st Mixer
			2.7 kHz
through		through
				6 kHz
Pre Amp		Post Amp
				15 kHz

IF BW 100 Hz	SWP	8.6 sec
	SPAN	2 kHz
	SPAN 100 kHz

Roofing filter-characteristic example BW=270 Hz

CH1 B/R log MAG	10 dB/ REF 0 DB
CH2 B/R log MAG	10 dB/ REF 0 DB

Main reception unit				AMP
1st Local Oscillator		Block Diagram
					Divider
					1/N
			82.78～	115.48～	1.8/3.5/5M	...N=10	AMP
			92.48 MHz	128.992 MHz
PLL	DDS		PLL		7M	...N=8
					14/18/21/24M	...N=4
			96.48～	127.48～	(other than these,
			107.48 MHz	138.992 MHz	DDS Direct)

DDS IC AD 9951

Comes equipped with ±0.1 ppm TCXO,

which combines high stability and energy saving

IF BW 100 Hz	SWP	8.6 sec
	SPAN	3.5 kHz
	SPAN 100 kHz

Roofing filter-characteristic example BW=500 Hz

The standard equipment includes a TCXO (Temperature- Compensated Crystal Oscillator), which stabilizes frequencies at ±0.1 ppm as the standard signal source. Unlike OCXO (Oven Controlled Crystal Oscillator), which requires warm-up time, this device can start up quickly even from the power-off position, while maintaining a high level of stability. It is in compliance with European energy-saving standard Lot 6. Power consumption in stand-by energy-saving mode is less than 0.5 W. A BNC connector on the rear panel provides

Mode	Phantom load	Start-up time
Stand-by	Or less	Approx.
power saving	0.5 W	40 seconds
Normal	Approx. 20 W	Approx.
		5 seconds

1st Mixer

10 MHz reference I/O.

7