mch wrote:
> Actually, 3 dB is the point at which you can first notice a change in
> the signal. As far as whether it is worth it is up to the individual.
>
> If a signal is 'fine', lowering it 3dB should not make it unusable. The
> change should be noticable, but that's about all. Of course, that all
> depends on the baseline of 'fine'.
>
> Joe M.
And remember-dB is relative. A 3dB change in power output will seldom
result in a 3dB change in signal strength at the other end. For these
kind of measurments, you need to do it with a sig gen in a 'closed'
circuit, ie, plug the coax directly in to the rx to eliminate fades,
'multi-path', etc.
Also, don't forget that 3dB is a factor of two ONLY if you're talking
about power. For voltage it's 6dB for a factor of two. so if you're
measuring rx sensitivity in uV, going from .5 uV down to .25 uV is 6dB,
not 3.
--
Jim Barbour
WD8CHL
>
> Chris Peterson wrote:
>
>>Many times I've read here that you can't hear the difference between 3DB.
>>
>>Many have used this argument to claim that an antenna with 3DB more gain is
>>somehow not necessary, or that someone should only run 50 watts rather than
>>100 watts because nobody will know the difference.
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