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Re: [TowerTalk] Mountain top multi tower QTH

Subject: Re: [TowerTalk] Mountain top multi tower QTH
Date: Wed, 14 Jul 2010 13:10:30 EDT
List-post: <">>
In a message dated 7/14/2010 9:31:35 A.M. Pacific Daylight Time, writes:

>  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 
everything in/out.
    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.  
Steve    K7LXC
Experience on dozens of commercial sites


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