AM IF filter

Posted on Mar 18, 2013

Typical QRP receivers include Direct Conversion (DC) and simple Superheterodyne types. These receivers often have quite a wide AF bandwidth which can make inteligiblity somewhar restricted, especially under difficult QRM conditions. Many commercial amateur transcievers also suffer from this t.ex the Yaesu FT101B.

AM IF filter
Click here to download the full size of the above Circuit.

This is a simple filter that restricts the LF response a little as well providing quite a heavy HF roll-off. The prototype has enhanced a Yaesu FT101B that was only fitted with an AM IF filter. The IC is an LM358. Construction needs no detailed description. Layout is not critical.

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