Steve,
With the G5RV dipole, you get reasonable VSWR on the major bands. On 80
meters it may get to 3:1 or so at edge of band but all my rigs with built
in tuners worked fine and never used an external tuner.
There is a myth out there, perhaps started by G5RV himself (!), that 80-100
feet of coax is needed. If you think about that a minute, you'll see that
the only purpose of the long piece of coax is to lower the VSWR (due to
it's inherent loss).
The easiest way to feed a G5RV antenna is to use a 1:1 current balun at the
end of the 450 OHm feed line (about 30-35 feet from the center of the
dipole). I use a W1JR type current balun, about 12-14 turns of RG142 or
RG303 PTFE 50 Ohm coax wound on a 2.4" diameter toroid. I also have used
about 50 ferrite beads like the W2DU balun. They al;l work great and many
are available commercially.
My son Jim, AD1C, has a similar G5RV only up 30-35 feet and has worked over
325 DXCC in the last 4 or 5 years! The G5RV is a compromise antenna that
does work and is not a DUMMY LOAD!
73,
Joe, W1JR
At 01:08 AM 7/6/2002 -0700, Steve G. wrote:
>Yep... it's hard to beat these simplistic center-fed antennas that Tom
>has described. Just match or "tune" these low loss antenna systems
>(system = antenna and balanced feed line) with a capable tuner, and work
>the world. A combination of low and high ones like the 100' or 135'
>models would serve stateside and DX interests. Just take into
>consideration their patterns when changing bands. BTW, many articles have
>been written on these balanced line, center fed antennas. They show the
>patterns, takeoff angles, and the varying amounts of gain they have for
>each band, considering different heights above ground. I'm sure someone
>can point out the specific articles - I remember one in QST a few years
>back. Who needs a G5RV with it's coaxial losses if you can bring "ladder"
>or open wire line into your shack? With a complete balanced line run from
>the tuner to the antenna, these are SUPERIOR and ELEGANT. I've enjoyed
>them at different locations over the years... though I sure wish they were
>at 100+ feet like Tom's!
>
>73, Steve, KZ9G
>
>At 01:20 AM 7/6/2002 -0600, you wrote:
>>A *simple* solution to the 100 ft space limited antenna problem
>>is to just install a 100 ft center fed dipole using Ladder Line feeders
>>and an Antenna Tuner such as a Johnson Matchbox.
>>
>>I have 4 Ladderline fed antennas (2 - 80M dipoles, 1 - 100 ft CF,
>>1 - 20M dipole) which I use extensively on 80M the WARC bands.
>>I have worked over 320 countries on each of those 4 bands.
>>(OK, the 80M dipoles are at 130 ft and the 100 ft CF is at 100 ft)
>>
>>Tom N4KG
>>
>>On Sat, 06 Jul 2002 "S. Markowski Jr." <km9m-zig@attbi.com> writes:
>> >
>> >
>> > Van K7VS wrote:
>> >
>> > > with a g5rv, keep your antenna tuner handy as you WILL need it
>> > for all
>> > > bands. Certainly a compromise antenna but useful in some
>> > instances.
>> >
>> > You "CAN" work alot of DX with a G5RV and 100 watts. You will learn
>> > one new character trait.....
>> > "PATIENCE"!
>> > 73,
>> > Zig KM9M
>> >
>> > _______________________________________________
>> > Self Supporting Towers, Wireless Weather Stations, see web site:
>> > http://www.mscomputer.com
>> > Call 888-333-9041 to place your order, mention you saw this ad and
>> > take an additional 5 percent off
>> > any weather station price.
>> > _______________________________________________
>> > Towertalk mailing list
>> > Towertalk@contesting.com
>> > http://lists.contesting.com/mailman/listinfo/towertalk
>>
>>
>>________________________________________________________________
>>GET INTERNET ACCESS FROM JUNO!
>>Juno offers FREE or PREMIUM Internet access for less!
>>Join Juno today! For your FREE software, visit:
>>http://dl.www.juno.com/get/web/.
>>_______________________________________________
>>Self Supporting Towers, Wireless Weather Stations, see web site:
>>http://www.mscomputer.com
>>Call 888-333-9041 to place your order, mention you saw this ad and take
>>an additional 5 percent off
>>any weather station price.
>>_______________________________________________
>>Towertalk mailing list
>>Towertalk@contesting.com
>>http://lists.contesting.com/mailman/listinfo/towertalk
>
>_______________________________________________
>Self Supporting Towers, Wireless Weather Stations, see web site:
>http://www.mscomputer.com
>Call 888-333-9041 to place your order, mention you saw this ad and take an
>additional 5 percent off
>any weather station price.
>_______________________________________________
>Towertalk mailing list
>Towertalk@contesting.com
>http://lists.contesting.com/mailman/listinfo/towertalk
|