On Jul 2, 10:35 pm, wrote:
That makes more sense. The selectable LC filters octave or fraction
of an octave?
I was looking at fraction of an octave, however I have yet to decide
anything more specific. Actually I started by playing with Ansoft
Designer to design the filters, keep being unhappy how they turned
out, and as a result keep having to increase the first IF to make it
easier to have good image rejection. I had naively started with 10.7
MHz as the first IF ... I may not have a lot accomplished, however
I'm certainly learning a thing or two. :-)
Generally it's antenna, a low loss selectivity, RFamp, Image stripping
filter then mixer.
What's the downside of doing the selectivity and image stripping as
one
filter prior to the RFamp?
I consider a RF amp at VHF/UHF of more than 1.5DB NF to be noisy.
This is because current technology for low noise amps are well under
1 DB to the 500mhz region maybe higher.
Care to mention a couple of model numbers?
-- John