Topband: Looking for experience with DHDL
Richard (Rick) Karlquist
richard at karlquist.com
Wed Jan 31 22:19:59 EST 2018
I recently built a 70 foot long 35 foot high DHDL that can be pointed
east or west by reversing the feed/termination. I tested it in recent
160 meter contests either west to JA or east to the US East Coast.
The comparison RX antenna was a low full size 160 meter inverted vee
with the apex at 40 feet.
The DHDL didn't exhibit any advantage to JA, and only exhibited
advantage to the east coast with a small number of stations.
When it did have an advantage, it sounded like 3 or 4 dB as the
100 degree lobe width would indicate. It modeled very well on
It was fed using a 16:1 impedance ratio "binocular" core balun
transformer. It appeared to be in good working order based on it being
very deaf to the north and west when aimed east. This is in comparison
to the low inverted vee which is basically omnidirectional.
The DHDL experience reminded me of my attempts to build beverages
over my high conductivity ground. A JA beverage was very deaf
to the USA, but didn't make JA pop out of the noise vs a low dipole
or even the TX vertical.
Can anyone share their experience with this design. It is possible
I am doing something wrong? What is a better design to try? I
should mention that I have 20 acres available, so I can go as big
On 1/31/2018 5:52 PM, GEORGE WALLNER wrote:
> I was out in the Bahamas for the CQWW160 contest from C6AGU. Both before
> and after the contest I got up to work JA-s at sunrise. There was
> definite peak in signals. The peaks started just at sunrise (06:47 local
> time) and lasted about 15 minutes. By 07:15 there was nothing on the
> band. It was similar during the contest.
> On Monday morning I was testing a new 80 meter antenna. The peak was
> very prominent on this band. I was working JA-s from about 06:15 and
> they were extremely weak (I had a good RX antenna and plenty of pre-amp
> gain). Starting just after sunrise, around 07:00 signals came up to S9
> withing minutes. I worked about 30 stations and most of them were loud.
> The peak ended very quickly: I was barely able to complete the last QSO.
> By 07:20 there was absolutely nothing.
> On Wed, 31 Jan 2018 15:31:14 -0500
> Guy Olinger K2AV <k2av.guy at gmail.com> wrote:
>> I actually wasn't hearing band peaks either, until I got to thinking
>> that, and went digging in the RBN stats. The peaks are there. So what
> Topband Reflector Archives - http://www.contesting.com/_topband
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