Re: ? ? dipoles

[Edward R Cole]

My very first ham radio antenna was made from TV twinlead which was
cheap and very accessible back in the 1950's when I started.  I made
a 40m folded dipole and feedline was also twinlead.  That I soldered
on a PL-259 connector to attach my Heath DX-35 which was 50-ohm
didn't faze me (it worked fine since the Pi-Net tuned to it).  Don't
recall there being any TVI (we lived in the country in an old farm
house).  Later on I migrated to VHF with Tech. License and built
yagis, but my HF antenna were old reliable and simple half-wave dipoles.

73, Ed - KL7UW
http://www.kl7uw.com
     "Kits made by KL7UW"
Dubus Mag business:
     [hidden email]

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

[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 <[hidden email]>
To: Elecraft Reflector <[hidden email]>
Subject: Re: [Elecraft] ? ? dipoles
Message-ID: <[hidden email]>
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:
     [hidden email]

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]