Scheyville NP for the Trans Tasman Low Bands Challenge July 2015

Scheyville National Park VKFF-444 in NW Sydney is one of the closest parks to home. I’d been looking for a good excuse to activate this park when the Trans Tasman contest came around. This contest runs at night from 6 to midnight local time. The first challenge was identifying a suitable operating location within the park. A lot of parks are secreted behind locked gates or are not accessible once the sun goes down and so it was that part of this park is too. In order to increase the chances of success I found a number of candidate locations beforehand and printed out the map to take along.

Antenna and operating point in Scheyville NP

Antenna and operating point in Scheyville National Park

Hunting
The map below shows the path while hunting down a suitable spot. The first location on Whitmore Rd came up with an open gate on google street view, but upon arrival the gate was locked. It provides access to an education centre and the Longneck Lagoon that I was keen to be located near. There goes that plan.
Around the other side of the lagoon off Cattai Rd (route 15) was the next option. There was a problem to actually get into the park as there was another gate, and another one further west along the road at option 3. There were also powerlines nearby too making it unattractive.
With those possibilities exhausted I cruised along the roads around and through the park looking for a suitable spot. Eventually I found an entrance to the park that wasn’t locked on Scheyville Rd. It led to a very muddy open area, and crossing this I almost got bogged. It was touch and go for a bit there whether I’d be able to drive out of it. Skirting around the edge of the area I found a track up to another open area a bit higher up. This was nowhere near as muddy and nice and flat. After a brief survey on foot, I decided this was a good place to set up.

Map of the hunt for a suitable operating location

Map of the hunt for a suitable operating location

New Antenna

For this event I built a new antenna a few days beforehand. It consists of a ZS6BKW design made with dimensions double the normal size. The resulting antenna is 56.5m long and has a 21.5m feedline of 300Ω ribbon. the theory is that doubling all the dimensions will halve the frequencies at which the antenna matches. The low bands challenge now covers 3 bands 160m, 80m and 40m with 40m only being introduced this year. This is the reason for building a new antenna. Last year I used a dual dipole (160m/80m), but being full sized it is a very long antenna and quite heavy. It was not considered prudent to add a third dipole on account of the extra weight and difficulty in setting it up.

I had time a couple of days before the contest to erect the new antenna in a local park and measure the SWR across various bands. The best matching frequencies were close to expected at 1830, 3460, and 7170 kHz. The SWR was as expected on 160m (3.6) and 40m (1.3) but on 80m was slightly higher than expected at 2.5. In any case, an antenna matcher is needed on all 3 bands so this was not going to be an issue. The arrival of a bunch of young netball players at the local park prevented any fine tuning so that will have to be held over for another day.

On site

The antenna was set up on site using a 10m fibreglass squid pole extended by a couple of 2m Aluminium mast sections strapped together. The resulting height was about 13m. There were concrete fence posts in the field so one of those was used to support the mast. The ends of the antenna were strung out in roughly a north-south direction and tied off 2m off the ground so the ends of the antenna were about 3m off the ground. The balanced feedline is best kept away from the ground so this was done by moving the car the right distance away and stretching out the feedline in the air and lashing it to a wooden fence post. An LDG matcher was placed on the back of the car and the antenna plugged in to it directly. The matcher was set up in automatic mode so that it tunes whenever there is a transmission. This is to allow for the many band changes and frequencies that would be used in each band. A small 3S 500 mAh LiPo battery provided power for the matcher. Just before the contest I spent time going to each band and tuning at various spots so that the tuner would not need to hunt when I started at a new frequency. For the most part, this worked pretty well, though at some frequencies the SWR was high enough that the tuner wanted to do a retune which takes about 3 seconds.

Feedline and antenna matcher on the read bumper

Feedline and antenna matcher on the rear bumper

Contesting

At the start of the contest I started out on 40m SSB and made several contacts, then it went quiet so I went to 80m SSB. There was a lot of action on that band and signals were coming from everywhere including many ZLs. I also started receiving unsolicited reports about how loud my signal was. Clearly the antenna was working!

After a short stint on 160m SSB with only 2 contacts made I went back to 80m SSB again. The onto 40m SSB before I went to CW on 80m – and there was lots of activity there too! After 20 mins there there was still 20 mins before the end of the first 2 hour block so I went to 160m for CW and SSB contacts. Activity had picked up on 160m.

Shortly into the contest I started to use VOX on the Yaesu FT100D radio even though I was using the standard hand microphone. The button on the mic gets a real workout in a contest and I did not want to wear it out and further. The VOX was reasonably successful, though occasionally it would stick on due to RF feedback. Knocking back the VOX gain seemed to cure this problem. The long cable from the mic to the radio don’t help here. With the KX3 radio I use a PC headset and it would be good to adapt the headset for use with the Yaesu rig too.

For the remaining 4 hours of the contest, I continued in the same fashion, jumping between 160m and 80m on SSB and CW. I found that 40m was full of DX stations mainly from Japan so it was difficult to get a SSB frequency. Even on CW there seemed to be lots of stations. The “problem” was that I was out of the city in a quiet environment with a massive antenna and hearing everything. There was hardly a contester using 40m so I think everyone must have thought the same thing and given it up as a bad job. I had wondered why 40m was added to the contest. It certainly helps the VK6s get involved in the early part of the event before the lower bands open up.

Results

During the contest 178 contacts were made which was very pleasing. On 160m, 18 CW and 18 SSB. On 80m, 43 CW and 87 SSB. On 40m only 1 CW and 11 SSB. Clearly 80m was the “money” band. There didn’t seem to be any WWFF chasers amongst the contacts even though an alert had been put up for the activation on ParksnPeaks the day before. The log has been posted to the WWFF database so that the 75 different callsigns worked receive credit for working the Scheyville National Park.

The double-sized ZS6BKW is definitely a keeper. Some small variations to the length need to be tried to see if the SWR on 80m can be reduced. This may require a change to the feedline length too. The centre frequencies are all optimum for this particular feedline so whatever changes are made to the design, it will have to be scaled to ensure the centre frequency is unchanged. If you’re looking for a single antenna that will cover 160m, 80m, 40m and 20m then I’d certainly recommend this one.

The access to the operating location was very muddy. My car was covered with mud top and bottom after this activation and required thorough cleaning to remove it. The site is only for the bold 4WD owner.

The contest was a lot of fun and the time passed very quickly.
Thanks for all the calls!

Equipment

  • Double-sized ZS6BKW inverted-Vee doublet on 13m mast
  • LDG Z-11 Pro antenna matcher, 3S 500 mAh LiPo battery
  • Yaesu FT100D transceiver, MH-42B microphone
  • Sennheiser HD201 headphones
  • Lenovo S10-3 notebook PC for logging
  • LED headlamp for operating at night
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2 thoughts on “Scheyville NP for the Trans Tasman Low Bands Challenge July 2015

  1. Hi Gerard, when I activated this park I was slightly troubled by noise (RF) from surrounding properties and audio from a loud lawnmower. I activated not far from the Park HQ. I noticed the High Tension transmission lines nearby in one of your pictures. I wonder whether you got any noise from that? Anyway I enjoyed reading your blog and the success you achieved from the Park is pretty special, especially when you consider your use of 160 metres. I think 80m antennas in the field are hard work, let alone one for 160m! I will probably head back to Scheyville when we visit our son and family over Christmas and New Year. I would like to build my score from that most interesting park.
    Cheers
    John D
    VK5BJE

    Like

    • Hi John,
      RFI from the high tension lines was a concern so I assured myself it was OK by listening on various bands on the mobile. After setting up the big antenna I found it to be quite good from the noise perspective even though my antenna ran parallel to the HT lines. There were pulses there that the noise blanker completely eliminated. The real test came when making contacts. There was no station that came back to me that I couldn’t work so certainly good enough. I was actually about 400m away from the lines. When I drove to the park HQ beforehand I did notice how high the noise level was there. Hopefully you will reach a better spot next time.
      Thanks for your kind feedback and comments.
      Cheers,
      Gerard – VK2IO

      Like

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