In a message dated 7/14/2010 9:31:35 A.M. Pacific Daylight Time,
> We all dream of that perfect site - 1000' above all else for 360
degrees. I found such a site, but so did 6 or so commercial
tower/transmitter operators before me. The towers range from 100 to
250', from guyed to freestanding, from VHF to microwave stuck all over
the height with sidearms. Three are high power FM/TV, multi-tenant
master antennas that have stations with ERPs of several 100 kw, maybe
one at 1000kw. These are about 200' away and start at 150' up and my
quick research indicates at least 6 FM broadcast transmitters. It
doesn't appear that there are any AM/HF transmitters from the antenna
> So is this worth taking a harder look, or is it hopeless for ham HF
operation? Some of the questions that come to mind are:
> 1. Can I put up a guyed tower (e.g. 90') with a swing arm stack?
codes are ok) Can the other tower owners/licensees stop me? What if my
tower affects their permitted pattern?
What you do on your tower is usually just your business. The same
holds true with the other owners/tenants. After all. would you expect them to
get your permission for changes/additions you make to your tower? No.
> 2. How much filtering will I need? I can imagine building a Faraday
cage ham shack for about the cost of a top of the line rig and filtering
How much filtering? More than you can imagine. This is an RF-rich
environment and it's going to come from everything; e.g. actual transmitted RF
with the attendant spurs; LOTS of noise from switching power supplies,
computers, etc. Everything's solid state, remember? Then there's the issue of
grounding. There will be some good grounds and some bad grounds. Even with
just one commercial user on their cell tower at the QTH of a local ham, he
went round and round to get them to meet the noise limits he put into the
contract. And this was only 100W or so.
Also, the rule of thumb for site interference is "last man in". In
other words, you're the person that has to solve your problems. Getting
commercial users to do anything about their interference to your equipment is
low, low, low priority for them.
My advice is to move on. It's much easier when you're on VHF/UHF and
higher single frequency where you can put in some big cavities and take care
the problem. You're proposing doing it on thousands (millions?) of discrete
frequencies. It'll never be an RF quiet location.
Experience on dozens of commercial sites
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