LOW PASS FILTER BLOCK 3.5-30MHz

This board consist of the following modules:

5 chebyshev type low pass filters to cover all bands

High voltage (210V) scheme

Antenna RX/TX switching

SWR directional coupler and measurement of Vfwd/Vref

Optional LPF (160m) connector

This module ensures clear harmonic output of the linear amplifier, also fits the components for antenna RX/TX switching. Following the “click-less” conception, there are no mechanical relays in the circuit. After long searching for suitable power switching component I found VISHAY high voltage rectifier diode S07J that met all the requirements for reverse voltage capacity, reverse recovery time, forward current and reverse voltage. So S07J were used in the project to ensure good switching of TX power to the antenna via proper LPF and also reliable isolation between each other low pass filters not selected for this band portion.

15109106_lpf

High voltage generated from input signal polarizes unused switching diodes in reverse direction ceasing the chance for signal leak. Same votage is used in RX/TX switch for completely disconnecting receiver front end on transmit.

 

 

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