For the ARRL 2010 CW contest over the weekend of 19/20 February I had planned to make a single band entry on 20m. I don't have a rotary beam antenna for 20m and I was going to try out a phased vertical array as an experiment. This is a 48 hour contest starting at midnight (UTC) on Friday and finishing at midnight (UTC) on Sunday. Stations outside of North America work the USA and Canada. Operating only on 20m would mean that I could get to bed at normal times over the weekend. An unexpected family arrangement meant that my 3 young grandsons were going to arrive on Saturday morning to stay for the weekend. The first thought was to pull out of the contest. The second thought was to go for a single band 40m entry. 40m will be open to North America at night when the children are in bed. I can easily put up a 40m quarter wave vertical so that was done.
The rig used was my very old Icom IC751A which I have fitted with a PIEXX CAT interface to allow computer control. This old rig has been a faithful servant and I still consider it to be amongst the best rigs I have used. For this contest I used the rig barefoot (i.e. with no linear amplifier). On maximum power output the IC751A produces about 90 watts. I have an external WinKeyer to allow my computer logging program (N1MM) to generate clean and stable CW to the rig.
An amazing thing hapenned when I had finished putting up the vertical at just before 1100 UTC on Friday 19 February. I came into the shack to check the tuning of the antenna and found it was fine. The CW end of the band was extremely quiet but I eventually found a CQ DX call...it turned out to be W4II in Alabama! I wonder if that's a good omen...read on to find out. Click the images to open larger versions in a new window for easier viewing.
Here's the 3D radiation pattern predicted by 4nec2X for the antenna being used:
After installing the quarter wave vertical I measured it's performance using an AIM 4170C Antenna Analyser:
The resonant frequency of the built antenna is 6900 kHz. This is found by looking at where the THETA plot (purple) crosses the x-axis from negative to positive. At this frequency the impedance is 55 ohms and is almost purely resistive (i.e. negligible reactance). The SWR plot (red) shows that over the wanted operating frequency range of 7000 kHz to 7100 kHz the SWR never exceeds 1.5:1 and the impedance only rises to a maximum value of 65 ohms with very little reactance. This being the case, it was decided not to bother adjusting the antenna to bring the resonant frequency slightly higher. The benefit from doing this would not be worth the effort.
Here are the propagation predictions VOACAP gave me for 2 important paths between my QTH and North America for the contest weekend:
GM to Boston
The 40m path from my QTH (SW GM-land) to Boston is likely to be open from around midnight UTC until 0900 UTC. There could be 2 periods of excellect propagation centred on 0500 and 0900.
GM to San Fransisco
The path to San Francisco could be good at around 0600.
UPDATE - 0850 UTC Saturday
The first 3 hours of the contest were busy on 40m. By 0300 I had worked 161 Qs in 32 of the 63 ARRL sections. I had no trouble working stations on both run and search and pounce (S&P).
I had a break for just over an hour from 0300 until 0415. Between 0415 and around 0500 I struggled to work anything on run or S&P so I had another break until just before 0630 when the propagation prediction indicated possible west coast US stations would be audible on 40m. Very few stations were heard from 0630 until about 0730. During this time I could hear east Europeans working runs of VEs and Ws - but I couldn't even hear the Ws and VEs. I accessed the Reverse Beacon Network web site to see if my CQ signals were being heard at any of the monitor stations. Here's what it was like while I was CQing at 0656:
You can see that none of the monitor stations is reporting my signal so propagation out of GMland on 40m had more or less died during this period. The yellow lines on the image above are 40m paths that are open but they are between southern Europe and the east coast of the US. Nothing is hapenning between northern Europe and W/VE. There was no sign of the anticipated opening to west coast W/VE at around 0600 so I just plodded on making very few contacts until 0730 when I decided to have a sleep. Seconds before pulling th big switch I heard a weak W6 and I worked him on the first call. That was the opening starting - an hour and a half late. For the next hour I worked into the west coast and the mid-west with no trouble. Signals were going up to S7/8 at times but were normally around S5. East coast signals also got strong at this time. I heard a KH6 but they count as DX for this contest and they only work W/VE just the same as us.
A spreadsheet showing the Reverse Beacon spots that were reported from my CQ calls during the contest is available here.
The score just now is 210 Qs and 34 of the 63 ARRL sections. The ARRL sections are mainly based on USA states and Canadian provinces.
UPDATE - 0145 UTC Sunday
I went back on 40m at 2350 on Saturday night to try for east coast W/VE. For about an hour I was very busy with the Q rate going up as high as 200/hour at times. After this initial burst things got much quieter. It was as though I had worked most of what was available in this hour. There were a few W6 and W7 calls. At 0145 I'm hardly finding any new stations to work either S&P or running so I'm pulling the big switch and having a sleep until just before 0600 when I'll come back on and see if there is any kind of west coast opening. It would be unwise to assume that because the west coast opening yesterday morning was an hour and a half later than the predictions that this will be the case again today.
The score now is 288 Qs and 40 of the 63 ARRL sections. There are no easy to find sections left - so I'm not expecting to get much over 40 sections. I'm also not expecting to take the QSO score much higher but I would like to pick up a few more DX contacts from the west coast and mid-west.
UPDATE - 0730 UTC Sunday
There has been no sign of any kind of west coast opening this morning. The stations I am copying on 40m have all been worked already. I think that is the end of my 2010 ARRL single band 40m entry. I don't imagine that it will be worth coming back on later tonight because I would most likely still be hearing only stations that are are already in the log.
Conclusions
The 40m quarter wave vertical performs well on most paths from my QTH to north America - I rarely had any trouble working stations I could hear. On Saturday night I had a significant number of calls from stations that were already worked - an unusually high number in fact. It's a wild guess, but it could be that these stations are using CW Skimmer and it was detecting my callsign with a slight error giving the impression that I was a different station. The periods when I was hearing east Europeans running pile-ups when I couldn't hear the W/VE stations was probably due to propagation conditions rather than my antenna. It's always a great feeling to work DX on the low bands and to have managed so many W/VE QSOs on 40m over the weekend was great fun. The highlights were some of the big signals from places such as California, Nevada and Nebraska.