Topband: Looking for experience with DHDL

[GEORGE WALLNER]

Rick,

I built two DHDL-s last week for the 160 m contest from C6AGU. One was 
pointed towards EU and the other one towards NA/JA. The EU one was longer at 
19 m vs. 16 m for the NA one. The two antennas behaved quite differently, 
with the EU one being excellent and the NA one very mediocre.
I was surprised because I have had two similar DHDL-s in November in the 
same spots. They were both 16 m long and 6 m high, and they were both very 
good. But, I "tuned" those antennas by adjusting the loading resistors for 
the lowest signal from the back. I did not do that for the new antennas.
I think that adjusting the loading resistors is more important than the 
transformer. Interestingly, with the two identical antennas, I got two 
different resistor values. One was 1200 Ohms while the other one was 1000 
Ohms. Perhaps the ground below them was different. (One was closer to the 
water than the other.)
George,
AA7JV


On Wed, 31 Jan 2018 19:19:59 -0800
  "Richard (Rick) Karlquist" <richard at karlquist.com> wrote:
> 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
> EZNEC.
>
> 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
> as necessary.
>
> 73
> Rick N6RK
>
> 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.
>> 73,
>> George,
>> AA7JV/C6AGU
>>
>> 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 about
>>> that, and went digging in the RBN stats. The peaks are there. So what gives?
>>>
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