5 MHz activation of Cleeve hill (G/CE-001) nr Cheltenham 4/10/08
I’ve been saying for quite a while that I should get out portable on 5MHz (and HF in the UK for that matter). I’ve done plenty of 2m SSB/FM activations but thought it was time to broaden my horizons. The Super Antennas portable vertical antenna which had worked far better than expected for HF activations while on my summer trip across Europe was found to be unsuitable for intra-G contacts because if its low angle of radiation so a more efficient antenna was required
I had built a linked dipole during the summer cut for 80, 40, 20, 17 and 10 metres which I’d not been happy with. It may have been propagation conditions on the days it was tested (vSWR good on each band) but it never appeared to radiate very well. Apart from the lack of confidence in the performance in the antenna it was very prone to getting knotted and took ages to untangle; this I thought would not be fun with cold wet fingers during winter activations. I’d seen flex-weave wire (the nice pvc covered multi strand cable) at a radio rally and thought it might be less likely to tangle (this has proved to be the case), so purchased a drum. Instead of a linked arrangement covering multiple bands (including those which would be covered by my vertical just as efficiently) I wondered about using a multiple dipole arrangement in an inverted V, which would not only make band changing automatic but would also help guy the support pole.
To reduce the complexity of the antenna only 3 bands would be considered for the design; 80, 60 and 40 metres. The arrangement of the antenna that has been settled on is for the 60 and 40 metre dipoles to be fed from a common point with 80m added by linking removable extensions to the 60m dipole; this configuration provides operation on two bands with the minimum of messing. A quick initial test of the antenna on a field close to home proved that it worked efficiently with a contact into Holland on 40m (during the late afternoon noise) and a reply to my call on 60m from Steve (GW7AAV), both with very good reports from my FT-817 running at 5W. As an experiment I turned the power down to 0.5W and still had a 5/7 report from Steve; just goes to show how good a band 5MHz is when conditions are favourable.
The weather forecast for Saturday was for rain across most of the country which was later changed to rain approaching the Midlands from the West at lunchtime. I was eager to try out the antenna again but didn’t really want to be out in the cold and wet with an antenna that may not work. I thought Friday was just a fluke! My nearest unactivated hill, which had plenty of space, with no obstructions and not too far from a car park (if a quick escape from the weather was required) was Cleeve hill (G/CE-001) near Cheltenham so this was the place chosen for my first 5MHz portable SOTA activation. Even though it was very windy (too windy to fly my two favourite kites, a 2m parafoil and a Revolution) the antenna was erected with the centre at about 6m above the ground and an initial call made.
At home I suffer badly from high levels of QRM on 60m (anything from S5 to S8 of noise) so it is a surprise to hear next to no noise on 5MHz (even on a field only 400m away from home) with loud clear signals. A couple of times I forgot that even if I could hear a station at 5/8 to 9 they might be struggling with me.
I apologise to any stations that heard me but was unable to work. In just under 30 minutes I had 25 contacts and unintentionally closed when the main support pole collapsed due to the high winds. With rain threatening and Helen (M3YHB) waiting patiently to activate the hill it was time to pack away the antenna. I’m very pleased with my very first 5MHz portable SOTA, the antenna worked well and hopefully it was not just another fluke.
I’ve a couple of modifications to the guy lines (so that they can be clipped easily to the isolators wearing gloves in the cold), another test on a easy hill to make sure all is well and then I maybe happy to rely on it for winter activations on some of the more remote hill tops. So expect me to pop up cashing in on the winter bonus points.