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The design of noise blankers were to eliminate the
impulse noise of our wonderful automobiles. Most noise blankers use a separate
RF front end on a frequency 5 or more Mhz removed from the main receiver
frequency. When the noise reaches a predetermined design level of blanking the
noise blanker ceases to blank the IF or audio signal in the main
receiver.
Noise blankers were never designed to function in a
base station/repeater station environment where you have very little
impulse noise. If one is operational at a station site, it could be totally
ineffective due to other signals causing interference on the noise blanker
receive frequency. Some types of power line noise will be reduced, however most
will overload the blanker.
The best advise is do not use a noise blanker at a
station site unless there is a very good reason to do so.
UHF Links: Almost every link is different. I to
have had low power links operate over 50 miles from high elevations to various
sites that were line of site. I have had a UHF link that required 100 watts on
both ends, mountain top to mountain top in Montana, 45 miles separation. There
was another mountain top in the middle of the path obstructing the
path.
Get a copy of com-shop and put an effort into the
path design that you want to have operational. Most reliable designs require
better that a 90% reliability factor for year round and all weather operation. I
have seen some poorly designed links that would only operate in the fall and
winter when the trees did not have any foliage on them and the user would
complain the other few months of the year and not spend any money to fix the
problem.
If your going to put in a UHF link - DO IT
RIGHT!
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