>From the bottom of the vertical to the bottom of the 40 meter trap will be
about 32 feet depending on the diameter of the vertical. The larger the
diameter of the vertical the shorter for a given frequency. The length above
the trap to resonate on 30 Meters will depend on the inductance of the trap.
I don't know what you are using but usually the 30 meter length would be
measured from the top of the 40 meter trap. Put it up, run SWR curves for
both bands and adjust length to resonate on each band. 73, Ron W8RJL
----- Original Message -----
From: "Dan Schaaf" <firstname.lastname@example.org>
To: "Tower and HF antenna construction topics." <email@example.com>
Sent: Sunday, April 18, 2010 9:27 AM
Subject: [TowerTalk] 1/4 wave vertical question
>I am building a 1/4 wave vertical for 30 and 40 meters with a coax trap.
> In order to do the initial measurements, can anyone tell me if the 30
> meter length includes the trap or if the 30 meter length stops at the
> bottom of the trap or in the center of the trap?
> Dan Schaaf
> "In the Beginning there was Spark Gap"
> TowerTalk mailing list
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