CAVITY FILTER MOD. 5 KW USER`S MANUAL
Contents
1. CAVITY FILTER MOD 5 KW USER S MANUAL Release 1 0 Mod 5K W GENERAL DESCRIPTION FM double cavity filters made in quarter wave high Q with fixed coupling realized in aluminium with internal line in silvered brass and copper The resonant cavity filter is used to avoid intermodulation problems that can occur when several transmitters are located close one to another Installed between transmitter and antenna provide an output free from spurious and isolation from other transmissions The equipments are usually set up in the factory on customer request They are otherwise set up at the centre of the frequency range TECNICHAL FEATURES Cavity design TECNICHAL SPECIFICATION Input output connectors EIA 7 8 Frequency range 87 5 108 MHz 3 dB bandwidth gt 600 Khz Power input 5 Kw Impedance 500 VSWR 125 Insertion loss lt 0 25 dB Dimension Width 600 mm Height 1200 mm Depth 300 mm ab Band of cavityfiter MCFDPOS set to 103 MHz 36 95 99 103 107 111 F MHz op Retum loss of cavity filter MCFDPOS setto 103 MHz 24 30 95 99 103 107 11 F MHz INSTALLATION AND USE To install the cavity filter inserting it between the transmitter and the antenna To use a 7 8 cable cellflex of opportune length to connect the transmitter to the cavity filter2. it is important to insert the inners in correct way Even if the cavity filter has been set in factory on the frequency of use it is essential however after the transport near the station radio reset in accurate way There are different ways to set the cavity filter among which two ways 1 To use a tracking generator and an spectrum analyser and to effect all the necessary regulations to get the least insertion loss in the frequency of use Fig 1 2 To connect the filter to the transmitter before with small power to insert a wattmeter between the filter and the anteenna To set the filter to get the maximum power of measured output on the wattmeter and the least ROS measured on the transmitter Fig 2 SPECTRUM ANALYZER TRACKING GENERATOR Fig 1 ANTENNA WATTMETER TRANSMITTER Fig 2 In the cavity filter they are only there 4 regulations 2 stubs and 2 turnable links The 2 stubs are regulated for centering the frequency of the filter the 2 links are regulated for to set the impedance to 50 ohms To regulate the stubs to unscrew the nut of stop 1 and to rotate the knob 2 For regolaree the links to unscrew under the EIA connector 3 to rotate 4 and to fix the screw 3 Normally after the setting in factory it is not necessary to regulate the links but only the stubs
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