[TowerTalk] Loaded vertical questions.

[N7mal]

WHY???? You're only 8ft short. Why not fashion a top hat. Without doing any 
fancy computer stuff I would think 5 or 6 3ft spokes would get you very 
close.
Just my -2cents worth
73


MAL
N7MAL
BULLHEAD CITY, AZ
http://www.n7mal.com
Everyone in the world is
entitled to be burdened
by my opinion

----- Original Message ----- 
From: k3hx at juno.com
To: towertalk at contesting.com
Sent: Thursday, March 12, 2009 20:53
Subject: [TowerTalk] Loaded vertical questions.


I'm working on a portable vertical for 7.03 MHz.

Maximum length is 25.4' overall.

I can place a loading coil at either the base or 17.9'

Ground losses are assumed to be 15 ohms.

I am having trouble getting consistent figures from different

antenna programs.  I've used "Mobile," the vertical antenna calculator

in the VE3ERP program and also a "longhand" version using the formulae

in the ON4UN book.

What I'm trying to determine is if it is worth the trouble to load the

vertical at the 17.9' level rather than at the base.

I'd be grateful from someone more computer-savvy than I who could run

the numbers.

I've got R rad at @17 ohms for an electrical height of @68.5 degrees.

I'll be homebrewing the lodaing coil from #14 wire and expect a loss

of @1 ohm thru the coil.  Maximum power @100 watts.


Shameless plug:  QRP-ARCI "Grid Square" Contest 14 Mar 09 1000-1300

EDST. Good folk, great fun!

72,

Tim