[TenTec] How to Hear the Weak Ones,

Robert & Linda McGraw K4TAX RMcGraw at Blomand.Net
Thu Nov 17 21:56:20 EST 2005


In reading through all of this it does appear that the antenna is the most 
upfront part of the station.  Certainly there are specific antenna designs 
and configurations that lend themselves to enhanced RX application.  While 
at the same time there are some the lend themselves to TX application or in 
some cases both RX/TX applications.  As to the receiver, I agree that 
today's modern receivers for the most part are very adequate technically in 
normal operation.  For multi station contesting or just contesting alone, 
certain features are most desirable.

One point that seems to always get overlooked and seems to be most 
mis-understood is the issue of noise as received and presented by the 
receiver.  Time and time again I hear comments on the air to the effect the 
"I have a S-9 noise level today".  Well sir, if you have a S-9 noise level 
the first thing you need to do is reduce the RF gain or add some attenuation 
on the input.  Regardless of your outside noise level, allowing the receiver 
AGC to pump up to an S-9 is simply sucking up good dynamic range that you 
will need to hear the weak ones in the presence of strong signals.  Don't 
get the idea that "more gain" will allow you to hear the weak ones, 
specially if you are amplifing random or unwanted noise.  Simply not a fact 
of physics.  I make it a practice to adjust the RF gain or attenuation so 
the S meter indicates no more than S-2 to S-3 on non-signal conditons.  You 
will be surprised how efficient the receiver will be and how much less 
fatugue will be experienced by the operator under these conditions.  And 
those weak signals will appear to "pop out of the noise".

The human ear is the most efficient filter system today.  Typically it can 
detect signals that are as much as 10 dB below the noise threshold or thus 
signals down in the noise.  This is where good confortable headphones come 
in to play complemented with an operating position that is not contaminated 
with acoustic noise.  Nothing like a 600 CFM blower on the amp screaming in 
your ears augmented by the TV in the next room.  Who needs this.

Finally, there's several good external DSP boxes on the market that do 
wonders for assisting in separating noise from signal.  Get one and try it, 
you might find you like it.

73
Bob, K4TAX 




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