BasicB-008-005-010

Your 2-metre station suffers receiver overload from several land mobile service transmitters on adjacent bands. What type of filter could help?

A
Answer
Safety
Type
A
Band-pass
B
High-pass
C
Low-pass
D
Notch

Answer Notes

Receiver overload from strong transmitters on adjacent bands means that unwanted RF energy from both above and below the 2-metre band is overwhelming the receiver's front end. To fix this, you need a filter that allows the desired 2-metre signals to pass while attenuating signals outside this range. A band-pass filter is the perfect solution because it passes a specific "band" of frequencies and blocks the rest. It essentially combines the properties of both low-pass and high-pass filters to create a window of acceptable frequencies allowing your receiver to hear only the 2-metre band. High-pass and low-pass filters only block frequencies on one side of the desired band, leaving the receiver vulnerable on the other side. A notch filter is designed to eliminate one specific narrow interfering frequency, making it unsuitable for blocking multiple transmitters spread across different adjacent bands.
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A nearby high-power HF broadcast station in the 31-metre band is interfering with your reception on the 40-metre and 30-metre bands. What type of filter is needed on the receiver to minimize interference?
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A filter attenuates frequencies above its cut-off frequency of 40 MHz. What type of filter is it?