[TowerTalk] Tuned Feeders
T. A. Russell
n4kg@juno.com
Fri, 26 Sep 1997 22:23:27 -0600
I have several Johnson Matchboxes, both the 250 W and KW
versions. The 250W versions handle 1KW with no problem
since they were designed for plate modulated AM which
has twice the peak voltage of an unmodulated carrier.
I have never heard an arc in the 250W tuners, even when
hit with a KW and the tuner was tuned to another band.
They do not have enough overlap to cover 30M but 12
and 17 can be tuned from either adjacent band.
An 80M dipole is 3/2 wavelengths on 30M, 5/2 WL on 17M,
and 7/2 WL on 12M (which means that a coax fed 80M
dipole will work well on the WARC bands). Since they
are all an odd number of half-wavelengths, they act as
current fed longwires, with their main lobes roughly
30 degrees from the wire. The 20M dipole has a
figure 8 pattern broadside to the wire. With those
two dipoles, I get nearly complete coverage of the
world with only two fixed wire antennas. Both dipoles
run N/S. Other 80M dipoles have lobes at the odd/rare
directions like JT, P29, and FT/W etc.
I bought my ladderline from The Wireman. He carries
3 sizes if I remember right and I selected the mid size.
de Tom N4KG
............................
On Fri, 26 Sep 1997 20:16:07 -0500 "Ron Stordahl [N5IN]"
<ron.stordahl@digikey.com> writes:
>Tom
>
>What are you using for an antenna tuner? Describe your ladderline,
>wire gauge, spacing etc? Full power? Are the 2 80M dipoles at right
>angles so you can select direction somewhat.
>
>Ron N5IN
>
>
>----------
>> From: T. A. Russell <n4kg@juno.com>
>> To: TOWERTALK@contesting.com
>> Subject: Re: [TowerTalk] Tuned Feeders
>> Date: Friday, September 26, 1997 8:35 PM
>>
>> Wet line may show an increase in loss but the antenna still works...
>> I have 4 dipoles fed with "ladderline" and use them on all bands.
>> Roughly 300 countries on each WARC band, all with wire antennas.
>> (Two 80M dipoles, 100 ft center fed, and 20M dipole which gives a
>> figure 8 pattern from 10 through 30 MHz)
>>
>> de Tom N4KG
>>
>>
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