160 meters is above the broadcast band. 3rd order should be above 160,
not lower.
lattice filters, many near 9 MHZ. for single sideband transceivers,
are used successfully.
Could take out more noise, than adding.
All the arguments against this could also be used against roofing filters.
73
Bruce
On Thu, 22 Dec 2016 12:56:21 -0800, "Richard (Rick) Karlquist" wrote:
Crystal filters are known to have a 3rd order intercept
point. Depending on how many AM BCB stations impinge
on your filter, you could get intermods. Switching
in an attenuator ahead of the filter should help,
if you can stand the increase in noise figure.
Rick N6RK
On 12/22/2016 12:41 PM, K1FZ-Bruce wrote:
We know that limiting the noise pick up from more directions of an
antenna we can usually hear better. We also know if we limit the
noise from a receiver IF we can hear less noise, and better yet, if we
have a roofing filter earlier in the receiver we can eliminate even
more noise in relationship to the wanted signals.
What if we take it a step further, could we limit the band-with of
the antenna signal with a crystal lattice for 160 meters before the
receiver.
Years ago I played around with a single crystal at the input of an
old tube type receiver. It was remarkable what I could hear on 40
meters, on what seemed to be one frequency.
73
Bruce-k1fz
http://www.qsl.net/k1fz/beverage_antenna.html
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