Gallery of photos from the VK9NA Dxpedition in 2011. Click any photo to view larger size, with slideshow control options.
Gallery of photos from the VK9NA Dxpedition in 2011. Click any photo to view larger size, with slideshow control options.
I am joining the VK9NA team for January 2011. All the details of this expedition are on the VK9NA.COM website. This is a VHF/UHF/microwave expedition which will include some 2m EME capability and will have reasonable power (75w) on 5.7 and 10 GHz too.
The station should be on the air by 9th January and will be active in the following weekend’s VK VHF/UHF Summer Field Day event.
More details on the VK9NA website vk9na.com
At the Dayton Hamvention 2010, I attended the VHF weak signal group dinner.
I met and chatted with a number of other people about VHF activities in Australia and heard discussions on contest rules that were familiar issues. Should contest points be based on distance or on grid squares, or power, or what?
In the US VHF sprints they are trying a distance based formula based on 6 character grid locators. They have found that this approach has been well accepted by contest participants. It is now quite feasible to calculate distances based on 6 character locators, since computers are so common. Maybe this is what Australian VHF operators would like. The grid square bonus system is much simpler but some people think it doesn’t give recognition or incentives for longer distance contacts.
It will be interesting to see whether they decide to keep the distance based scoring formula.
After lugging all my equipment for 50, 144, 432, 1296, 2400 and 3400 MHz from the car to the north side of the summit at Mt Ginini, it still took several hours to get set up and operational. I finally got on the air on all bands at around 6pm, after making some earlier contacts on 1296, 2400 and 3400 with VK1BL and VK2AES.
Later I made contacts were made with VK1BL/p and VK2AES/p on all six bands (3400 only with VK1BL) but conditions and activity from further afield seemed quite poor with only weak signals from a small number of other portable stations.
I was running my station from a newly purchased inverter generator. This was not a name brand but an import sold by a Victorian dealer, mostly marketed via Ebay. I was pleased that its noise performance was much better than my previous generator. However at about 9pm on Saturday night, within 20 minutes have having its fuel topped up, it slowly ran down and stopped. All efforts to get it going again were unsuccessful. I SMSd the other local field stations telling them I had a power problem. The next morning I could only pack everything up and go home.
What happens to the generator has not been resolved yet. My confidence in this particular unit is zero. I have not been able to restart it, despite following the advice of the dealer and changing the fuel to premium unleaded. I can believe it would run better, but I don’t see why it would simply fail to restart on ordinary unleaded.
I did examine the spark plug and found it was fouled considerably. The recoil starter still reveals compression is good so I don’t think the rings have given up. I suspect ignition circuit failure.
Fortunately others didn’t have this problem and went on to make more contacts. The contacts with Doug 4OE did not work out too well, with Ted VK1BL making only marginal contacts on 144. Contacts on higher bands were not possible. Conditions were simply too poor.
Better luck next time.
On a trip to Sydney I checked for the VK2RSY beacons on 28.262, 144.420 and 432.420 to see how far out I could hear them.
I was surprised to find I could hear the 28 MHz signal at Sutton Forest and within a few km the 144 MHz beacon was also clearly audible. The 432 MHz beacon was very weak at that point but in the next 20 km it became quite readable. It was interesting to compare the signal levels from these beacons over the next 100 km or so of my trip. The best signal strength from the 144 and 432 beacons was at the start of the downhill slope on the highway just after Mittagong, heading towards Sydney. At that point the 432 MHz beacon signal strength indicated S5, with the preamp ON.
On the way back home from Sydney I recorded the beacon signals and the files are available here, in both MP3 and AMR format. I used a Nokia mobile phone to record these signals – not the most elegant recording method but it’s a start. If you have software to play or convert the AMR format, the AMR file format produces more compact files. I used Miksoft.com’s converter to produce the MP3 versions.
Recording 1 of VK2RSY on 432.420 and 144.420 in MP3 format 1.4 MB – 1 minute, mostly the 432 MHz signal but at about 15 seconds you hear the improvement in signal strength and quality when I switched over to the 144 MHz signal and then back to the 432 MHz signal a few seconds later. AMR format 42kB
Recording 2 of VK2RSY on 432.420 and 144.420 in MP3 format 1.4MB – 1 minute – starts with the 432 MHz beacon and at about 20 seconds, I switched to the 144 Mhz signal and back again. AMR format 42 kB.
I was struck by the apparent change in quality observed when switching between the beacon frequencies. When I was stationary, both signals sounded clean and pure. While mobile the 432 MHz signal showed considerable multipath and smear like a 10 GHz sigal with doppler or rain scatter. I am not sure exactly what caused that effect on this signal . Apart from the blur or smear of the signal there was also at times a second version of the signal on a slightly different frequency, which I assume was an aircraft reflection with doppler shift.
I was asked why I didn’t also check for the signal from the 6m beacon on 50.288. This was an obvious omission from this experiment and I did have a 6m antenna I could have substituted for the 10m helical. Something to try next time. I’ll also try to record that doppler effect signal.
This post was originally set up as a “page” but in a redesign of the site I decided it should be a post instead.
As we had scheduled a house move one week prior to the January 17th VHF Field Day, I had to set aside the equipment needed for the field day so it wouldn’t get packed up and be lost for months, which can happen when you move house.
The antennas were no problem as I had to move them on the roof racks of the car. The cables were a possible problem, as were the connectors, camping gear, tent/poles, generator, power cables and distribution boards, power cables for radios, the radios themselves.
The one thing I could not put on hold was myself and I had worked very hard for 5 days straight packing and carrying boxes of household goods. The last move took ages and I had several weekends to sort through 3 garages and dispose of unwanted stuff. This time was a bit better, there was only one garage.
The upshot was that with some encouragement from Dale VK1DSH I did find the energy to pack the car early on Saturday morning and head up to Mt Ginini, a 70 km, 90 minute trip from the new QTH. It took a bit longer as I called in at the bakery and the supermarket for some essential supplies on the way.
We got the station set up by about 3pm and logged our first contacts on all bands. Right away there seemed to be antenna problems on 52 and 432 MHz. Both antennas came down, connectors checked. The 52 MHz vertical had been extended to make it work on 50 MHz on a previous field day. Removing a short length of tubing added for 50 MHz operation returned it to normal operation on 52 which was sufficient for local contacts.
On the 432 antenna, lowering that meant going off 144 as well so we had to get it done quickly. I inserted the Bird 43 meter inline with the 432 MHz feedline and first tried a dummy load on the antenna side of the meter. Perfect, very low reflected power, transmit power fine. Same with the dummy load at the antenna end of the feedline. But with the antenna, quite poor swr at about 2.6 measured at the transmitter end. Later I ran some simulations using the predicted loss in the feedline (CNT400, 10 metres) indicated that the actual SWR at the antenna was somewhat higher. This indicated the driven element of the antenna was not properly connected to the feedpoint connector. however it was sealed in epoxy and nothing I could do up the mountain to fix it. Note that I had previously used this antenna with poorer quality feedline RG/9. The increased losses of that feedline masked the antenna problem.
On other bands all appeared to be working fine, though I never made a complete contact on 1296 with Adrian 2FZ in Sydney, nor with Dave 2JDS near Bathurst. However I made a number of contacts at similar and greater distances into the vk3 area so it remains a mystery.
With Dale 1DSH operating the 6m rig and the IC910 running on 144, 432 and 1296 it was a noisy tent at times. The radios were all together on one table. The other radio on the same table was the FT290 which was the driver for the 13cm transverter.
Dale brought his 10 GHz equipment and made a contact back to Ted VK1BL on Mt Ainslie in Canberra on the Sunday morning. No other 10GHz stations were active within range. Unfortunately the power amplifier in Dale’s transverter suffered a failure so power output was limited to around 1 milliwatt.
Packing up only took 90 minutes, half what it had taken in November. A great pleasure to be on the road heading home at that time. On the way I heard Norm 7AC on 50.170 and had a 10 minute chat with him from the car. Just for a bit of extra radio for the weekend! But I forgot to get a Ross Hull contest number from him. 11 points lost from the RH log!
After scoring the log it appears we did fairly well on 2m and 432 despite the antenna problems. The log has been sent in on time so we will see what the increased activity level does to our position in the results.
Photo gallery for Summer 2009 VHF field day.
I use spreadsheets to record my field day log. I don’t need to use a computer in the field – I work with computers all day and the last thing I want on a field day is yet another day of working a computer. A paper log is quite good enough, and avoids odd things happening due to incorrect program logic, or wrong callsign recording.
In the John Moyle Memorial field day rules you need to record the grid locators of stations worked on vhf/uhf. Then you need a column for distance, then you need to work out the points earned by that contact.
I use Tiny Locator, a nice little application from ON6MU, to calculate distances from grid squares. There are spreadsheet add-ins available for Excel, but I decided to just use an external tool and copy/paste its results into my spreadsheet. By doing the calculations only once for each callsign, the process is cut down to the minimum effort required.
I copy all the callsigns worked, with their locator codes as recorded during the contest, into a new worksheet called Grids. Then I sort by callsign and remove the duplicates. Then I do all the distance calculations with the help of Tiny Logger and record the distance for each station worked.
Back in the log page itself I then insert formulas into the Grid locator, distance and points earned cells of each row.
The grid locator can either be the original locator recorded during the contest, or the data copied from the Grids worksheet for that callsign. Similarly for the distance and points data.
The formula to copy the grid locator for any callsign in the Grids sheet is =VLOOKUP($E2;$GRIDS.$A$1:$C$28;2) for OpenOffice sheet users, or =VLOOKUP($E2,$GRIDS!$A$1:$C$28,2) for Excel.
Similarly you can get the distance using the next column of the Grids sheet.
The points are calculated using a similar technique. The score table is set up in another sheet, in the following format.
The formula to look up the points for a distance is: =VLOOKUP(K2;$Scoretable.$A$1:$B$6;2) for Openoffice.org Spreadsheets.
Here $K2 is the cell containing the distance for the contact made. Scoretable is the sheet containing the table above in cells A1 to B6. Column 2 in the scoretable is the column containing the points to be scored. VLOOKUP returns the row containing the distance that is equal to the specified search value. If that exact value cannot be found in column 1 of the table, it matches against the first row found that is greater than the value sought. Thus a distance of 80 is greater than 49.9 but less than 99.9, so the row chosen is the one with a distance of 99.9, allocating 5 points to the contact.
You could continue to refine the formulas and the fine details, such as dealing with decimal points of distance correctly. eg. what is the score for a distance of 99.999 km? The simple table and formulas used would give the wrong result and strictly speaking the scoring table specified in the rules does not state the score for distances between 49 and 50 km, etc. However as a way of saving typing and avoiding keying errors in distances, this approach works well enough. Rounding the distances appropriately is also something to consider.
Using a combination of plain spreadsheets and formulas, you can ensure the grid locator, distance and point score for each contact is consistently recorded in your log sheet.