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New Valves for Small-Boat Radar

From The Radio Constructor, August, 1960.
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The installation of radar in a growing number of fishing boats, yachts, and the like, has led to radar equipments designed specifically for use in small, craft. Apart from the general demands of high performance and reliability, the essential requirements of such equipments are low cost, small size and weight, and low power consumption.

To meet these requirements the radar manufacturer needs valves that are also designed for the purpose. Mullard have already made available a 'line-up' of valves for 3 kW small-boat sets, and they have now introduced a new series of three types - a magnetron, klystron and pulse modulator - intended for 6 kW installations. Details of these three types, which were shown for the first time at the Instruments Electronics and Automation exhibition, are given below.

6 kW X-band Magnetron: type JP9-5

The JP9-5 is an inexpensive, low-voltage packaged magnetron giving a nominal peak output power of 6 kW (minimum 5 kW) at a fixed frequency in the band 9.345 GHz to 9.475 GHz. It requires an anode voltage of only 4.5 kV and has a peak current rating of 5 A. Its overall physical dimensions are small - 11.4 cm x 10.1 lcm x 5.1cm - and it weighs only 2.5 lb including the magnet system.

Pulse Modulator Valve: type QV12-P10

The QV12-P10 is a hard valve pulse modulator capable of a peak pulse output power exceeding 100 kW with a DC hold-off voltage of 12 kV. These ratings ensure that the valve is only lightly loaded when used in service with the JP9-5 magnetron.

The QV12-P10 is octal-based, and measures 13.3 cm x 5.5 cm.

X-band Local Oscillator Klystron: type KS9-40

Despite its low cost the KS9-40 provides a very high standard of performance and has several features hitherto confined to valves costing much more.

An important feature is its high frequency stability, due largely to the construction of the tuning cavity. Although an integral part of the valve, the cavity is external and thus is isolated from the effects of variations in beam current. The warm-up frequency drift is less than 3 MHz, 5 minutes after switching on. Rugged construction enables the valve to withstand accelerations of 10g with no more than 2 MHz shift in frequency.

The noise performance is very good, the typical AM signal-noise ratio being greater than 160 db per cycle of IF bandwidth for receiver intermediate frequencies above 25 MHz.

The valve is fitted with a WG16 waveguide output to take a plain flange coupling. A matching screw is incorporated to ensure close tolerance of output power, eliminating the need for a waveguide attenuator to control crystal current.

Mechanical tuning is provided over the range 9.3 GHz to 9.5 GHz, with an electronic tuning range between half-power points of ±20 MHz. The output power is 40 mW at resonator voltage and current ratings of 300 V and 35 mA.

Overall dimensions of the KS9-40 are 8.6 cm x 4.1 cm x 5.1 cm.

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