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Technical Information Sheet C158-EO

Novaris Pty Ltd ABN: 33 065 427 23272 Browns Road, Kingston, TAS. 7050 TEL: +61 3 6229 7233AUSTRALIA FAX: +61 3 6229 9245

Copyright 2000 Novaris E-mail: sales@novaris.com.au

COAXIAL SURGE PROTECTORS - HIGH POWER

Lightning strikes to antenna masts, towers and otherstructures induce large voltages into coaxial antennafeeders. The Novaris series of coaxial feeder protectors

provide protection for high power transmitters with largediameter coaxial feeders.

The protectors utilise an in built adjustable spark gap with a

patented optical arc detector. The arc detector provides a

signal via an inexpensive optical fibre to provide amomentary transmitter shutdown.

Thus the traditional problem of RF energy maintaining the

arc is overcome and a closer tolerance spark gap can bemaintained to provide lower spark over voltage for

enhanced protection for solid-state transmitters. Options forall EIA flange type connectors and solid line are available.

Applications

MF Broadcasting

HF Broadcasting

FM Broadcasting

Television

Defence Communications HF Radar

Features & Benefits

100kA surge rating

50kW power capability

50ohm impedance

26dB return loss

< 0.1dB insertion loss

Patented optical arc sensor

Momentary TX shutdown to extinguish arc

Description

Novaris high power coaxial feeder protectors consist of ashort length of solid coaxial feeder fitted with EIA flange

connectors. The feeder section contains a calibrated andadjustable spark gap electrically connected to the cable

outer. The gap is determined by the transmit power level -the gap must not arc under maximum peak power

conditions.

The arc detector is integral with the feeder section. A

photodiode detects the presence of an arc and signals via aninexpensive optical fibre to the transmitter interface

circuitry. The optical fibre eliminates any possibility ofinduction within the building due to differential earthpotentials. The interface circuitry provides a momentary

shutdown signal to the transmitter.

The major benefit of this arrangement is that the gap settingcan be minimised, and hence the sparkover voltage

minimised to provide enhanced protection for thetransmitter. With conventional spark gaps the gap settingmust be wide enough to ensure that the arc is not sustained

by RF energy.

The protector may be installed in pressurised or non-pressurised systems. The arcing chamber is isolated from

the airflow so that possible arcing products do notcontaminate the feeder. Air is bypassed through the hollowinner conductor to isolate the arcing chamber.

This product is protected by patent.

Specifications

Description: Coaxial surge protector with optical arc sensor

Surge Rating: 100kA peak impulse current for 8/20us impulse

Surge Element: Spark gap, gap setting 2mm/10kW

Spark over voltage: 2.6kV for a 2mm gap

Power Rating: > 50kW, limited only by coaxial cable powercapability

Characteristic

Impedance: 50 ohms

Insertion loss: < 0.1dB to 500MHz, < 0.2dB to 1GHz (gap

setting 1mm)

Return loss: > 26dB to 500MHz, > 20dB to 1GHz (gap

setting 1mm)

Arc Sensor: Optical detector utilising photodiode, feedingtransmitter interface electronics to provide

momentary shutdown.

Power Arc sensor 12V DC @ 35mA.Requirements: Power supply included.

Transmission Arc detector signal fed to

medium: transmitter via optical fibre to eliminateinduced transients in building.

Options

Cat No. Connectors

C158-EO 1 5/8 EIA / EIA flange connectorC318-EO 3 1/8 EIA / EIA flange connector