Nautel NX5 AM, Руководство по предварительной установке

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NX5 PRE-INSTALLATION MANUAL RF OUTPUT REQUIREMENTS
PAGE 1.6.2 VERSION 0.1 2015-08-01
Antenna Feed Cable
Maximum Voltage
The maximum voltage at the transmitter’s connection to a 50

load is 2.0 kV peak, when operating at
5 kW, with 140% modulation, at a VSWR of 1.5:1.
High Voltage Feed Throughs
Be very careful whenever a high voltage RF conductor passes through a wall or bulkhead. Gas
insulation flashovers can occur in poor installations. Ensure that this part of your installation is installed
by professionals experienced with high-power radio frequency circuits.
Insulator Flashover
Surface flashovers along an insulator occur when there is an electrical breakdown in the gas (normally
air) at its surface. The mechanism that triggers a flashover depends on the insulation surface conditions.
Gas breakdown flashover occurs when one or more of the following conditions are met:
 The voltage field at the insulator surface or at an adjacent electrode reaches the critical
breakdown level for the gas.
 The electrode or insulator interface is poor or dirty, resulting in a three material junction. This
creates excessive high voltage stress on the air insulator, causing a gas breakdown flashover.
 Moisture damage on the insulator surface creates regions of high voltage that can cause a gas
breakdown flashover.
Three-Material Junctions:
A frequent cause of breakdowns at an insulator surface is the junction of three materials: a metal
conductor, a solid insulator, and a gas insulator. The insulators form a capacitive RF divider between the
metal conductor and the grounded periphery. Since the dielectric constant of the solid is higher than the
gas (air), the high voltage stress is concentrated on the air.
It is important to minimize the junction's stress gradient and to avoid three-material junctions wherever
possible.
WARNING!
FAILURE TO PROVIDE CORRECT STRESS CONTROL AT HIGH RF
VOLTAGE CONDUCTOR/INSULATOR JUNCTIONS CAN CAUSE INSULATOR
BREAKDOWNS OR EVEN FIRES.