[BULK] - [TowerTalk] RG-11 Source?

[Jim Brown]

On Wed, 9 Feb 2005 19:50:54 -0500, Tom Rauch wrote:

>We had dozens of large headends that used the worse possible
>thing, straight through 11 and 13 with strong local stations
>and no conversion. 

Channels 11 and 13 are NOT severe -- there is vertical directivity 
in their antenna system that knocks their signal down by AT LEAST 6 
dB and probably 10 dB in the 1-3 mile range. The example I gave was 
within one mile of the transmitters, with the client TV sets 30 
stories up and with a direct view of the transmitting antenna, and 
with transmitting antennas that have virtually no vertical 
directivity. That puts VERY high broadcast field strength on the 
coax going to the user set. Our problems here are NOT high band VHF, 
where there is vertical directivity, but on LOW band VHF where there 
is not. 

For years, I've heard wireless mic engineers in LA, for example, 
tell me about the high field strengths they have "from all those 
towers on Mt. Wilson" that are 10 miles from the nearest receiver. 
Even though they are probably running 10 dB more power based on 
their location west of the Miss and grandfathered license, my 
condition is at least 10 dB (and probably 20 dB) more severe than 
theirs. 

Jim Brown  K9YC