Phil Allison wrote:

Michael Terrell wrote:


Adjacent channel interference like that is caused by the IF bandwidth
and the skirt. The IF transformers aren't brick wall, the amplitude
drops away slowly outside the desired bandwidth.

** FM receivers have multiple stages of IF band limiting making the falloff very sharp outside the needed 200kHz.

That allows a local
station to be strong enough to cause problems.

** Nope - the FM detector ( ratio or quadrature) is also tuned to the centre of the IF strip and will not demodulate an out of band signal.


More Phil****, as always. It's a damned good thing you didn't design
and build deep space telemetry equipment. Even business radios used
expensive crystal filters to reduce adjacent channel interference,
instead of 50 cent IF transformers. Digitally tuned FM receivers can
still receive an adjacent channel, but more than a channel away it
becomes quite distorted. Go back to hacking old stereos.

--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.