[Top] [All Lists]

Re: [TowerTalk] Mountain top multi tower QTH

To: "" <>
Subject: Re: [TowerTalk] Mountain top multi tower QTH
From: "Jim Brown" <>
Date: Wed, 14 Jul 2010 06:31:26 -0700
List-post: <">>
On Tue, 13 Jul 2010 20:03:54 -0700, Grant Saviers wrote:

>1. Can I put up a guyed tower (e.g. 90') with a swing arm stack? (county 
>codes are ok)  Can the other tower owners/licensees stop me?  What if my 
>tower affects their permitted pattern?

If there is an AM broadcast tower there, especially a multi-tower 
directional array, something you want to do could distort their pattern. 
That could lead to problems. An AM BC tower on a mountaintop site is 

>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.

You will need to deal with the pin 1 problem in your equipment. You will 
need to learn to bond cable shields to the shielding enclosure at the 
point of entry. You will need to use very good receivers (K3 or better). 
You will almost certainly need good bandpass filters if you want to work 
VHF or UHF. Study the RFI tutorials at

>3. If I filter enough so my receiver isn't totally overloaded in the HF 
>bands, will the transmitter to transmitter IMD products get me?  Or misc 
>rectification or phase noise?

If the intentional transmitters are all at VHF and UHF, most, if not all, 
of the TX noise is probably there too. That noise can be considerable, or 
not, and there could be a lot of it on adjacent VHF/UHF ham bands. BUT -- 
these sites may also include HF noise generators in the form of all sorts 
of digital equipment, switching power supplies, etc., and some of them 
may be quite noisy. THAT'S what I would be most concerned about. 

>5. Is there an index to licensees if I know the tower lat/lon?

Detailed info on broadcast licenses is at

Click on the AM Query, FM Query, and TV Query, then plug in lat/lon and 
set the radius as desired. You will get a list, then click on each call 
sign to get details of TX and antenna system. This site is the mother 
lode for broadcast info in the US. In general, FM and TV TX antennas are 
multi-element vertical arrays have gain in the vertical plane. This tends 
to focus energy at the horizon, and spill a bit less down to the ground 
than would an omni antenna. Info on non-broadcast TX may be harder to 

73, Jim Brown K9YC


TowerTalk mailing list

<Prev in Thread] Current Thread [Next in Thread>