graphic by TF3JA:
On February 2, 2010,
in Amateur Radio,
by TF4M
On February 2, 2010,
in Amateur Radio,
by TF4M
CQ 160 Contest – TF4X #2 in Europe, #6 World !
Yuri, K3BU operated TF4X in the CQ WW 160 meter contest in the Single Operator High Power category.
A solar flare about a week before the contest started caused worry that conditions would be poor. The band seemed to have recovered nicely, but the Aurora Index stayed high during most of the contest and it became clear that conditions were disturbed.
Iceland is greatly affected by any Auroral disturbance, much more so than neighboring countries and Yuri observed, for example, that my Great Beverage antennas showed almost no directivity during the contest. I know for a fact that they work very well, but during the weekend it seemed that signals appeared to come from all directions simultaneously. I understand this may be due to a high arrival angle during disturbed conditions.
Some juicy DX was worked, two KH6 stations for example, it is only recently that the historic first QSO with KH6 was made from my station – this is quite remarkable considering the disturbed conditions.
The raw score is as follows:
1643 QSOs
51 States/Provinces
80 Countries
Total Score = 1,317,729
At present TF4X has the second highest reported score in Europe and is #6 worldwide. This may of course change as and/or when other stations report their scores, but it is incredibly satisfying to see all my hard work being justified with such superior results.
It was quite illuminating to observe such an experienced operator running my station – at times I feared that my amplifier would literally melt, but it performed to my full satisfaction and there were no equipment/antenna issues whatsoever during the contest.
Yuri wrote in his comment to the 3830 Reflector:
Last minute adventure to the Aurora zone, taking up Thor’s invite.
Being rusty from dormant period, problems with equipment setup,
drivers, but got ready for the start.
Stories about Aurora wipeouts made it a big if.
Thanks to Thor and his magnificent station it ended up being fun and decent
score, even if coming short of beating the Eu record.
The background noise is probably the lowest in the world allowing to
hear lot more of the juicy stuff than working it.
Thanks for wonderful hospitality and station from Thor, TF4M and all the QSOs
and points. Lot of dirty clixing signals and rude behaviour by “CQ pirates”.
Will have more later.
Yuri, TF/K3BU
I used my PERSEUS SDR receiver to record the entire contest 1800-1900kHz. The recording obviously contains the entire contest effort of TF4X and in addition it contains the contest effort of everyone else heard at my location.
This consumes two hundred GB of data, please contact me if you are interested in specific time periods.
A new chapter in the History of Amateur Radio has been written.
On January 14, 2010,
in Amateur Radio,
by TF4M
The very old and worn chain puller I have been using for my antenna construction has been shelved.
I had several near accidents when using it and I have acquired a beautiful ratchet lever hoist with hook suspension
which almost fits in my shirt pocket and can pull 250kg.
I look forward to the next antenna job using such superior equipment.
On December 28, 2009,
in Amateur Radio,
by TF4M
On December 2, 2009,
in Amateur Radio,
by TF4M
The Arctic King is a relatively simple structure, but there are some aspects of the design that are not immediately obvious.
An inverted L antenna mirrors another inverted L antenna working against elevated radials, positioned right on the edge of salt water for more than 180° of the horizon.
At present the vertical wires going to each inverted L are tied together in the feed point box. This makes the antenna work as a T antenna against elevated radials.
In this mode – i.e. vertical wires working in Common Mode (CM), the antenna is fully resonant around 1838 kHz – a little bit high on purpose – ball park resonance was adjusted roughly by adjusting the length of the elevated radials and fine tuning of the resonance was done with a coil connected to the center point of the elevated radials inside the feed point box and one terminal of the UNUN transformer.
There are no tuning devices in the box, i.e. the resonance adjustment of the antenna is entirely separate from the matching to the feeder.
At resonance the feeder matching is accomplished with an UNUN 4:1 i.e. 50:12.5 ohms, and the UNUN additionally provides the DC path for the entire structure to a buried ground system.
I mention somewhere on my web site that initial testing comparing this antenna with my old tx antenna for 160 meters showed a 15 dB increase in signals, but I have now done some more testing and in the salt water direction the difference is in the region of 30-40 dB.
The primary purpose of the Arctic King is being a vertically polarized antenna, but by separating the two vertical wires inside the feed point box, the antenna can be fed in Differential Mode (DM) as a low dipole antenna – again resonant on the frequency of choice at 160 meters.
This would create a high angle of radiation, useful for local contacts like EU.
When the time comes to accomplish this, resonance will be determined – my measurements indicate 1770 kHz in DM and the resonance will be shifted with a capacitor connected between the two vertical wires inside the feed point box.
If the resonant frequency is high in DM, a coil will be installed instead between the vertical wires to adjust resonance, and the resulting R will then be matched to the feeder.
(note that in CM, these resonance adjustment components will ´disappear´ in CM, since they are effectively shorted out )
The interesting thing that was discovered during modelling was that once the elevated radials were raised to around 4 meters above ground, the dimensions of the top loading wires became non-critical.
This fact made it possible to calculate first the dimensions for the DM (dipole),then use those dimensions for the CM (vertical T ) and then adjust the CM antenna (the vertical) for resonance by adjusting the lengths of the elevated radials without affecting the resonance of the dipole.
I installed 8 conductors + shield from the shack into the feed point box to control relays and make measurements.
Current will be measured on each vertical wire and on each elevated radial and the balance will be adjusted as necessary.
In addition, the vertical will also be made to work on 80 meters in both CM and DM.
On 80 meters the feed point will be at a very high impedances, this is the reason for the separation of wires from the wooden structure and the large insulators.
The Arctic King is a unique antenna professionally designed by Villi, TF3DX and I am certain that in due time, he will publish a paper detailing the Arctic King design.
