QRP-Lers,
If You have access to 300 ohm ribbon twin lead, cut one-half of the
dipole for 30 meters (one side of the ribbon cable, one ribbon cable can
make 2 dipoles), then the bottom half part of the twin lead for 20
meters, that way, You have a 300 ohm ribbon twin lead, with the top part
of the ribbon cable, cut for 30 meters (1/2 wave) & the bottom half for
20 meters (1/2 wave). I had made up another one, for 17 & 15 meters. They
are feed, at the center, with RG-174, no traps, no tuners, and they roll
up nicely into my back pack with either my Sierra (N6KR design) or
GM-30/20/17/15 combo (NN1G design). The idea for this is from "The ARRL
Antenna Book", 14th edition, 1982, page 8-3. I was looking for light
weight antennas, for hiking around in the Mountains. For example, You
could build (I have not done this combo yet) a 40/30 meter dipole with
300 ohm ribbon twin lead, where the upper part of the ribbon cable (top
wire) is cut for 40 meters & the bottom half (bottom wire) is cut for 30
meters. You will find using the old 468/Freq. (MHz) will make this dual
combination a bit long, but You can prune it. If none of this makes any
sense, I can upload a few *.JPG files on to the W5BI web page, and show
You what I am talking about. Essentially, You take 300 ohm ribbon twin
lead, trim the top wire part of the cable for 40 meters, the bottom part
of the cable for 30 meters. It becomes a dual band (resonant) antenna,
light weight. All fed with one feed line, tied to 3 insulators.
What You have is a dual band antenna, using 3 insulators, fed with one
piece of coax, in the center. In this case, RG-174 for QRP purposes.
RG-58 for QRP & QRO purposes.
Anyone want to build a WIMPs antenna, using this method ? 30 meters on
the top wire of the 300 ohm ribbon cable (1/2 wave dipole), with 17
meters on the bottom wire, of the 300 ohm ribbon cable ? Fed in the
center with RG-58 or RG-174.This same technique works well with 450 ohm
ladder line too.
How many days until QRPTTF (April 26th) ? (22) We (W5BI, WB5LYJ ,
WA5WHN & possibly K5JS) will be live, overlooking one of the (alledged)
Corona, NM debris Fields, "near" the following coordinates, Lat. 33
degrees 56.575 minutes N, Long. 105 degrees 17.821 minutes W. A word to
the wise, street vehicles will fail miserably in this terrain, and these
are trails, not roads, plus they are unmarked. This is the middle of no
where (desert). W5BI's 4WD pickup has 16" of ground clearance, I have 15"
of ground clearance, in my 4WD vehicle (Measured from the differential,
on level ground). We have access to the Capitan Repeater (146.61 MHz,
W5YFN). 360 degrees of viewing the desert, except for the El Capitan
Mountains, 22 miles to the south of us. Where is everyone else going to
be for QRPTTF ?
72...Jay, WA5WHN DM65qd
[
QRP-L Archive |
]
[
1993 |
1994 |
1995 |
1996 |
1997 |
1998 |
1999 |
2000
]