Topband: DXE 8 Verticals

[Richard (Rick) Karlquist]

This is a confusing issue.  Changing the links in the DXE amp definitely 
changes the gain.  Whether it also also changes
the signal to noise ratio depends on the relationship between
external noise picked up by the antenna, the antenna preamp
noise, and the receiver front end noise.  Because the DXE
system is challenged by using 8.5 foot CB whips, we cannot
automatically say that the external noise dominates.  Thus
there is no general answer.

An additional confusion by users is that they want enough
gain to get significant AGC action on those weak signals
just above "ESP".  With many radios, this requires a lot
more signal than what is necessary to overcome the front
end noise.  Thus we find that the great majority of users
insist that they need a preamp, when the preamp is really
improving AGC range rather than signal to noise ratio.
(A separate discussion would be what is wrong with most
receiver AGC systems and how to fix them, but for most users,
they're stuck with what they have.)

The simplest way to avoid these problems to simply use
taller and fatter verticals, preferably with top loading.
I like to use 30 foot lengths of 2 inch aluminum irrigation
tubing.  However, not all users have the ability to do this.

Rick N6RK



On 2/20/2012 12:42 AM, David Cole wrote:
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>   I have used both the Hi-Z and the DXE 8 circle - maybe I am missing something but gain is one thing and signal to noise is another!
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> Does changing the links in the DXE amp improve the signal to noise? if its just gain then that can be achieve many other ways.
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