Kenwood TS-990SHF manual Transmit, Thermal simulation example

HF/50MHz TRANSCEIVER TS-990S Transmission unit /cooling

Transmitter performance, featuring high-scale specifications,

can withstand long periods of operation at full power.

Operating stably even when continually working over long periods of time, such as in competitions.

Built-in automatic antenna tuner capable of high-speed operation

The built-in automatic antenna tuner is a preset type that covers amateur band frequencies rang- ing from 160m~6m, and can be switched in on receive too. The tuner is capable of rapid QSY based on instantaneous band change, using a relay system that is known for high-speed operations. The relay, inductors, and coil use large-sized com- ponents that are able to bear the 200 W output.

Transmit

It is outfitted with four antenna terminals, which can be set independently on amateur bands, whether main band or sub band. The reception input and output terminals can be used for reception dedicated antennas, antenna output for external reception devices, and external BPF connections. It is usable with either the main band or the sub band.

	ANT				RX OUT		RX IN
1	2	3	4
			MAIN BAND				MAIN
			ANT Selector			MAIN RX ANT	BAND
					RX	OFF	RECEIVER
				AT		ON
					TX	SUB RX ANT	SUB
			SUB BAND			OFF	BAND
							RECEIVER
			ANT Selector
						ON
							Transmission Unit

High reliability design promises stable operation at 200W

Cooling system to send a sufficient volume of air to each unit

The device uses POWER MOSFET VRF150MP, which runs at 50V, with push-pull. You can obtain a high, stable output of 200 W on all bands. You can achieve superior IMD properties by pursuing bias and matching conditions in order to fully exploit the

3rd order TX IMD 14.2MHz / 200W
-10
-30
-50
-70
-90
10 dB / div	SPAN 10 kHz

FET attributes. Further, you can realize Kenwood’s distinctive tone by amplifying the clean modulated signal produced by DSP with an amplifier that ex- hibits excellent linearity.

Cooling is very important to obtain a stable output of 200 W. Heat dissipation efficiency is increased in the TS-990S through a large fin-type aluminium heat sink. An independent variable-speed fan is provided for the switching power supply, final unit, and antenna tuner, cooling each unit with a sufficient air supply. The switching power supply and the final unit have twin cooling fans. Noise is reduced by controlling the fan speed according to the temperature.

Thermal simulation example

To dissipate the heat of the 200 W final, we used swage fins instead of the conventional extruded aluminum fins. Using CAE analysis we designed the optimal fin shape and size for heat dissipation.

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