[TenTec] RF gain and S meter

Rob Atkinson, K5UJ k5uj at hotmail.com
Fri Feb 10 09:08:21 EST 2006


<<<That is, I want to see the true S meter reading independent of the 
setting
of the RF gain control.  I like being able to see the strength of the signal
stay the same while decreasing the RF gain to eleminate band noise.>>>

What you need is a noise filter.

<<<I am merely stating that I would like the
RF gain to be independent of the S meter and prefer it to work like it does
in the 1.xxx version of software, instead of the way it works in the O2 and
the 2.0 firmware.>>>

But I thought you said what happened in the earlier versions was that the 
meter reading would drop with a drop in rf gain.   That's not being 
independent.

I have operated rigs that work both ways.   When I started running Kenwoods 
and Yaesu (which had meters that were vacuum flourescent bars) and ran the 
rf gain down, the meter bar would light up to equal the increase in 
attenuation.  For example if the noise level was S7 and I reduced the rf 
gain N db to equal a drop of 7 S units, the meter would run up to S7 and any 
signal above the noise level would register on the S meter.  It took some 
getting used to because I was uncomfortable with the sight of the meter 
running up when I was _decreasing_ the gain.   It is one of those things 
that makes sense when you think about it, but runs counter to intuition.

If you have a rig where the s meter drops with a drop in gain, a station may 
be strong enough to make the meter wriggle, but if you say "You're S2" you 
are giving an innacurate report anyway.

It's like the airplane taking off on the opposite moving conveyor belt 
problem.   The question is If the conveyor belt moves at the same speed of 
the airplane but in the opposite direction, will the airplane take off?   
Most people answer that it won't be able to because their intuition tells 
them that, but the correct answer is that it will take off.   Once you think 
about it you see why.  This is kind of the same thing.

rob / k5uj

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