Friday, 4 November 2016

A little bit of band action, antennas down, and Gainmaster replaces Gainmaster,

I had planned to write something about computers and EMC, but that seems to be taking longer than expected. So here is a round up covering what has been happening chez FVM.

There have been a few short openings here on the VHF bands, notably an aurora on 25 October. Not a large event but nice all the same. On 4m I worked GI4OWA (again!) and G8VZT, both on SSB, and LA9BM on CW. I am trying harder with CW, particularly during aurora.

Towards the end of October there was a period of high atmospheric pressure. As I do not get out well on tropo to the south I had to wait for an opening in other directions. On 30 October I worked  Denis EI4KH via the Mullaghanish repeater on 145.750, in County Cork. The distance to the repeater from here is 628km and nicely positioned at South West and clear of the hills at my end. I could not raise anyone else either on the repeater nor on simplex. I did however work Derrick, GM4CXP, in Kelso, also via the Cork repeater. I also worked Eamon, GI0BDX on 2m SSB.

On 31 October I worked OZ5NJ and OZ1BEF on 2m SSB. Once I had realised that I was not beaming the right way, and conditions came up a bit too, I was hearing them both almost 59. At 664 and 704 km that is good for tropo for me. During the same event other GM stations with a clear take-off to the South were working into France. I have to take the rough with the smooth. OK, I do not hear stations in that direction, but I do well enough in other directions.

HF has been quite good too, despite the sagging solar index. The same heightened solar activity which pepped up VHF has been good to 10m. I read all the woe and misery in the band reports about high K numbers, but never a word is spoken about the Es this can bring on 10m (and 6m). EA3LX was worked on 6m 15 October when I was running up and down the bands following the variable MUFs caused the fluctuations. The 10m Es in this period were very nice, bringing in several far-away Russian stations such as RN6AM (KN95 3086km) and RX6DF (also KN95, 3096). I doubt, though, that Es was responsible when I called CQ on 10m JT65 and immediately worked VU2PCL in Bangalore (MK83 8090). That, I suspect, was just being in the right place at the right time. Likewise on 31 October I was appreciating the 10m Es by working EA3GJO on JT65 when I worked PU1KDX (GG87 9565). This followed PY4XX (GG88 9458) caught in similar fashion on 27 October. Best DX on 10m was CX8ABF on 17 October (GF15 11301).

Who said 10m was dead? (FVM never gives up on projecting his own sweeping generalisations onto others, does he?)

These things go to show two points. Es is around a lot, and like the same period last year, it is easy to see the link between enhanced solar conditions and bursts of Es. Then again, if you are around enjoying the Es you might work VU or PY alongside your other activities. The secret, as always, it that to work people you need to be on the bands. Sitting watching computer screens just does not do it.

40m produced the same batch of surprises as it has done for some time. With my lowly dipole I have been hopping round Europe, adding the more distant W8FHF for good measure. Calling CQ on 22 October brought back VK5ZK (PF94 16303), a surprise at just 20:32 on JT9 mode. 40m continues to amaze me.

Meteor Scatter has not been great here. I worked OZ1JXY and SP9HWY on 4m, but conditions were not as good as I hoped. The Orionids did not produce much of a peak.

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I have taken down all the antennas on the gable end of the house extension. This involved removing the 4m vertical, the 6m beam and the 40m dipole. Also removed were the rotator, the brackets and the guy wires. I am still in business with the 2m and 4m beams, plus the 10m and 2m verticals.

This all stems from the realisation that climbing and using wall brackets is not practical for me any more. Supporting the weights involved is no longer something I can do on a regular basis. So I have decided to go for a second tilt-over mast. That might sound a bit excessive, but I have no intention of putting up any more antennas. I just need to be able to work on them from the ground now.

Although the new mast can be cranked up, I do not intend to raise it above ridge tile level (5.2m) plus space to turn it. Once sorted, the 6m HB9CV will go up there, with the 2m vertical re-located from the other mast. I am not sure if the 4m vertical will ever go back up given the collapse in activity on that band round here.

So it will look like what has been up before, with the 2m vertical replacing the 4m one, and without guy ropes and so forth. I can hang the 40m dipole from it too. It should reduce the ragged appearance of all the guys and rationalise two masts into one. Maybe later I will put up a rather better 6m antenna, but that is not crucial.

It looks a bit bald, after I used the scaffold tower to remove all the clutter ...
I will have to manage without 6m and 40m until the new mast is up aloft.

Maybe soon I will not need the scaffolding tower either...
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Part of the same anti-clutter movement, also intended to make things look less conspicuous and more robust, I have changed my beloved Sirio Gainmaster vertical for a Sirio Gainmaster HW vertical.

When first released the Gainmaster had just one version - a 5/8th dipole, end fed. This is what I view as the ideal 10m antenna, requiring no radials and capable of working reasonably well on 12m. However, the years have passed and Sirio have released a half wave version, the HW.

I have been very happy with the original version, save for a couple of points. It is very long. In fact, in old money, 28 feet tall. This is high enough to be seen all round the village. Also, being fibre glass, it whips about a lot in the wind. We get a lot of wind here, up to 130km/h and more. So it is not just large, it is whipping about like a demented bamboo cane.

The Sirio instructions advise that the original version should be guyed in high wind locations. I am very reluctant to guy it as I already have guys for the 40m dipole and it might just attract more attention to it. So the half-wave version, which is "5 feet" shorter looks like just the job.

I have remarked before in this blog that it is very difficult to replace a good antenna with a less good one. It is hard to step back from performance you once had. All the same, I am doing it in this case. I know that the HW Gainmaster will not perform as well as the Original. But I have a need for something smaller, less wind attracting, less conspicuous and with most of the performance. So the HW it had to be.

The two antennas are constructed much the same way. The HW does not need the tuning arrangement in the middle, and only has three fibreglass sections. It is easy to construct, with the sections joined together with "Jubilee Clips" (aka worm drive hose clips).
The photo shows it stretched out before assembly (as usual, click to enlarge if necessary). The internal cable can barely be seen above the lowest section. You feed this through the upper fibreglass tubes and cut to length.

There is a table to show how to set the length of the upper sections. I set this for the bottom of the 10m band, allowing some extra for a later fine cut. Once connected I got a very strange reading from the antenna analyser in the shack which showed a resonance below 10m and a stronger one above , at 32MHz. Once I left out the co-ax from shack and measured the resonance at the antenna, this top resonance disappeared, so there is something wrong with the co-ax. I have wired it up as roughly cut and I will run new coax later.

It works. I have already been using it on 10m. Unlike the Original, it cannot be seen from the street. However I am not going to kid myself. This half wave version is never going to work as well as the 5/8ths one. In general terms, less wire means less performance. The angle of radiation will be higher and the efficiency lower. Not much mind you, maybe a couple of dB, which I am willing to accept for now.

I have taken the 5/8th Gainmaster apart and it is in the garage antenna mortuary. It might yet come to life again and see the light of day, later.
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That is it for now. Since we last communed I have visited the Galashiels Rally and I hope to say more about that later. For now though, as the great Edwin Starr might have wished you: Happy Radio.

73

Jim
GM4FVM

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