[Elecraft] ? ? dipoles

[Edward R Cole]

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 <wunder at wunderwood.org>
To: Elecraft Reflector <elecraft at mailman.qth.net>
Subject: Re: [Elecraft] ? ? dipoles
Message-ID: <C55A4704-F93F-4F79-A244-FB80E455F47F at wunderwood.org>
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:
     dubususa at gmail.com