My 600m inverted-L is something like those shown by Walter:
http://www.kl7uw.com/600mINV-L.jpg
http://www.kl7uw.com/EMEfrosty.jpg
http://www.kl7uw.com/Coil005_1.jpg
Quarter-wave at 472-KHz is 248/F = 525 feet
(which is too high for me) so 43/525 = 8% of a quarter wave.
Two wires for top hat to increased capacitance
and three wires in vertical to lower Q for
bandwidth (I get about 7-KHz which covers the
472-479 KHz band). Coil is 10-inch diam by
11-inch long with windings 1/4 inch
spacing. Form is white plastic food cutting
board sawn up. Hardware is all brass.
Z = 0.8323 j668.5 at 503 KHz from EzNec; Rrad = 0.83 ohms
I measured my antenna with loading coil in series
with my MFJ-269B antenna analyzer (analyzer
grounded to the antenna radial ground post): Z = 18 + j0 at 501 KHz
Total Power Radiated: TPR = 100 * (Rrad/18) = 4.6w
I run 100w output into coax feed: RF ammeter
reads 1.4 A. Amplifier is converted NDB
transmitter shown at top of this picture:
http://www.kl7uw.com/Rack_closeup_2011.jpg
73, Ed - KL7UW
From: Walter Underwood <[email protected]>
To: Elecraft Reflector <[email protected]>
Subject: Re: [Elecraft] ? ? dipoles
Message-ID: <[email protected]>
Content-Type: text/plain; charset=utf-8
Some of the early ?clothesline? antennas were a
large capacity hat on a vertical. If the antenna
has one vertical wire connected to all of the top
wires, it is probably a capacity-loaded vertical.
This Wikimedia image shows a top-loaded vertical.
https://commons.wikimedia.org/wiki/File:Amateur_radio_T_antenna_1912.png
<https://commons.wikimedia.org/wiki/File:Amateur_radio_T_antenna_1912.png>
With longwave communication, a resonant antenna
was not practical for most hams, whether
horizontal or vertical. I certainly don?t have
room for a half-wave for the 600 meter band.
wunder
K6WRU
Walter Underwood
CM87wj
73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[email protected]
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