Tom, N4TL, and I are separated by about the same distance as you and your
neighbor. We're both contesters and DX'ers. We do have some differences,
Tom prefers SSB where I prefer CW. That gives us some solace from interfering
with each other. However, during contests we often vie for the same
stations...that's unavoidable and we just tolerate the extra-loud signals for
the short while.
First of all, address the fundamental component of the station, the
What is key here is that first and foremost, you both have "clean"
rigs...minimal phase noise and clicks. Once you've both taken care of those
problems (filters won't cure problems on the same band, just the type of rig
and mods to insure the cleanliness of the signals will do that), then you can
address harmonics, often taken care of by bandpass filters or coaxial stubs.
Good receivers are a requirement, not an option. There are lots of
comparative analyses of receiver and transmitter performance (look at ARRL
product reviews, and the in-depth reports available to members, on the ARRL
web site.) Don't forget that extremely strong signals may cause non-linearity
in your own receiver (as well as your neighbor's), which is why filters will
minimize their effect when either of you is on another band.
Good beam antennas (e.g. at least three elements on a yagi) will afford some
front-to-back attenuation, and, generally even more front-to-side. Quads and
log-periodics can't make the same claims. Another thing about yagis, they are
monobanders and thus provide some attenuation of harmonics (the more
attenuation, the better, under neighborly considerations!). Tri-banders don't
offer the band-to-band isolation because of their inherent nature (that's the
I don't know enough about verticals to speak of it, but I suspect that "near
field" signals as well as the omni-directional aspect of such an antenna (not
an array!) would definitely be something to avoid.
Of course, use well-shielded coax (like "Bury-Flex", RG-214, or hardline) to
keep the r.f. contained in the transmission line. Cheap coax usually has
minimal braid allowing quite a bit of signal leakage (in and out).
Oh, and another thing: remember to use only as much power as you need to do
the job. Tom and I can operate very very close (frequency-wise) using just
our transceivers. It's when we kick on the "afterburners" that stresses our
receivers! And, speaking of amps, remember that phase noise and key clicks
get amplified along with the desired signals, so it's better not to have
those problems to start with.
Good luck, enjoy your hobby as well as your neighbor's,