Monday, 29 February 2016

Wimo 7ele 2 metre beam repair and antenna matters

Hi.

Some time ago during a storm my Wimo 7ele 2m beam shifted and had to be re-installed.

I mused at the time that about fact that it was mounted off centre might have been factor. I also mentioned before that it whistles in the wind.

Well during a short spell of still air I luffed the mast over and rebalanced it. Or, to put it another way, unbalanced it.
With the mast tilted over you can see the greenhouse. This close building means that there is only (roughly) 1 metre space on one side and a 6m beam will not fit sideways, nor any antenna with more than a 2m boom will fit lengthwise. Unless I move the mast (moving the greenhouse is not allowed).

That Wimo antenna has a fixing which allows it to be placed anywhere along the antenna except the middle. In the middle is a boom joiner, so the fixing does not fit there. I held the antenna along the boom until I found the weight balance point and supported it there. This is with the idea that (at rest at least) all the antennas should as far as possible be weight balanced around the mast, taking strain off the rotator. Great idea.

However, the weight balance is not the same as the wind balance. The elements are round section and the boom is square section, presenting different resistance to the wind. Net result, there seemed to be too much antenna beyond the mounting point. Or so it looked. And the boom is very light, meaning the antenna developed a bit of a "droop" towards the front.

Whether all that caused it to shift I cannot say. But shift it did. While working on it this time I took some photos of the resultant tear in the mast.
You can see the marks above the mount. I left it at the lower height ...

That is a strange mounting bracket, providing as it does for slight elevation of the boom. I like that as most meteor scatter operators do indeed put in a slight elevation, but then only one bolt fits on the top. Indeed they only provide two bolts. So it all seems a bit open to movement.

I moved the mounting point 400mm towards the front of the antenna. You can now see the boom joiner on the right, so I am near the middle of the boom. Once back up, there has been no whistling in the wind. It looks better balanced front/back, though of course with more elements towards the back it is clearly unbalanced for weight. But will it rip off again? I hope that it stays where I left it.

It does have a slight droop towards each end. Longer Wimos have double fixings and supports. Maybe this one needs those too. Aw no, if I have better supports maybe a longer antenna should go with them ...

I have been thinking again about the 1m limit to one side. This has resulted in my 6m band antenna having to go onto a different mast and therefore it is a very small and light antenna. I could do better with a 6m antenna on the main mast. I would move the Wimo to the secondary mast (it is small and light enough for that). But what 6m antenna is only 2 metres wide? A half wave for 6m is of course about 3m wide, so no conventional beam will fit.

Two solutions that I have thought about are quads and Moxons. I could build a quad (none of the commercial ones fit) but they are also tall and would be too close to the 4m antenna. A Moxon would just about fit (2.180m wide is just about possible, resting on the greenhouse glass!).

I am thinking about building a 4 element Moxon like the ones Vine used to sell. Not sure about that. They are a very unconventional antenna and I am not sure if the claimed gain figures can be realised in real life.

We shall see.

Antenna structures for us ordinary humans are all about what is practical and what we can afford plus what we can squeeze in. For the great DXers such issues are mere quibbles. I am determined, if I do build a Moxon, to spend nothing on materials and use the bits I have lying around. This is not just my miserly attitude to life; I do not want to spend any more money on this.

Do I really value 6m so poorly?

73

Jim
GM4FVM

Friday, 26 February 2016

More about X-Rays and Es.

OK, OK, I said I would not do this to death even more that I already have. But ...

... this post (link below) seems to have got people talking. Or at least e-mailing me.

http://gm4fvm.blogspot.co.uk/2016/01/sporadic-e-and-x-ray-bursts.html

That was about a month ago, but regular readers (poor souls) will know that I do tend to go on about this.

Right, after various enquries I decided to carry on with my researches for another 4 weeks, one week of which has now passed.

And what have I found?

1) That on days with no X-Ray peaks there was no Es.
2) On days when there were X-Ray peaks, there were 10 metre band Es openings within an hour of the peak
3) When there was a sudden big peak the opening extended to 6 metres
4) Between 09:00 and 15:00 the openings were here in GM, after 15:00 they were in North America.

This is not a just a week's findings. This is confirmation of months of observations.

It started when I was watching for signs of likely aurora. I noticed that raised solar activity was associated with Es, but if it was really powerful it caused an aurora instead. I watched it for months before mentioning it here and to Tim Kirby, the VHF columnist of Practical Wireless magazine. Tim reported it enthusiastically. Then people started to get interested and the e-mails started flying.

Since then I have narrowed it down to watching some pretty specific numbers for X-Ray flux within certain wavelengths defined by specific bands. I do not totally believe the DX cluster as it has many false positive and false negative results. However, I can usually find these and exclude them. Otherwise I am checking it out using WSPR.

I am not suggesting that, if it is true, that this relationship proves that X-rays cause Es. Far from it. Es are caused by all sorts of factors. What I am doing is presenting the findings and leaving it to others. However, I do think it is possible that, given the presence of Es conditions with an MUF lower than, say, 28MHz, a spike in X-Rays flux could raise the MUF enough for me to notice. Or possibly the two are just related rather than being cause and effect - though I have considered and rejected several things which trend the same way as the X-Rays.

As for the details of what I am observing, that will have to wait. Too dense to post up on a blog. However, I will write it up in due course. If you look back in my blog you can see what sort of things I have been watching in the past.

I cannot say more now because the observations are taking AGES. I am making observations for 6 hours per day, every day I can. It is REALLY time consuming. So more later.

In the meantime, here are some details for those who believe that Es is a Summer phenomenon (and who reading this blog can think that?)  ...



If you sense a different tone in this posting, so do I. I am finding this all a bit of a chore. This is supposed to be a hobby. It doesn't feel like that just at the moment. I feel more like a post-grad student up against some kind of a research deadline.


73

Jim
GM4FVM

Friday, 19 February 2016

IC-7100 firmware update E5 - new compressor settings.

I see that there is another update on the Icom website.

http://www.icom.co.jp/world/support/download/firm/IC-7100/release_e5/

This fifth update "E5" claims:-

Improvements
• The power meter’s visibility is improved.
• The speech compressor function is improved.

The reference to the speech processor is interesting given the various reports about low power on SSB.

I installed it last night. There was a bit of a panic on and I was called away in the middle of doing it. I forgot to back up all my settings and memory channels - bah!

Anyway, the update does what it claims by updating the main CPU to version 1.11 (mine was 1.04). Also it updated the DSP I version to 1.03 (from 1.02)

Strangely it also updated the controler CPU version from 1.00 to 1.10. I say strangely because it did not say it would do that. I imagine you would have to if the power meter's visibility was to be improved.

The display does look better but I cannot really say that I see much change in the readout (it might be wider).

Anyway, I think that most IC-7100 users will be interested in the speech compressor changes. Does DSP I v1.03 offer a solution to our stated issues?

The thing is, I don't have any issues any more as I do  not use the compressor.

What I found before was that no settings of the mic gain or the compressor could produce SSB output power levels matching what I expected. Maybe that is fixed now. More tests needed, as I often say.

Does anyone who used the compressor before and has installed the update wish to comment?

In due course I will give it a whirl and see if I can notice anything different.

Right now I am too busy trying to reset all my memories.

73

Jim
GM4FVM

Thursday, 18 February 2016

Propagation reports on my Android, and update.

We VHF-ers do like to know what is going on. I suppose that other Hams need information too, but the fleeting openings up here on the roof of radio mean that we require to be fully informed. Plus I am paranoid, which only makes it worse.

Allard, PE1NWL helps a lot of with the e-mail "DX Robot" service he offers from Gouda. I have mentioned it before but I cannot find it in my earlier posts (I cannot be bothered to look through all those wafflings I made over the past year to put in a link). You can find DX Robot by clicking here. It really is great.

Basically you can sign up to e-mail warnings of VHF activity on Es and Aurora. These reports are culled from the internet via cluster reports. You can tailor the DX Robot's reports by band, depending on where you are, e.g. North America or Europe, and the aurora can be selected by latitude too. Or you can just get emails of cluster reports.

DX Robot is brilliant in that it communicates with your PC by e-mail. But now Allard has gone one stage further. He has produced an app for Android which gives updated reports on a mobile phone or tablet. It is called EsSense.
It is still in beta and it is currently free. You can find it in the Android app store or click the link here.

I have been trying EsSense for a few weeks.

Now,  I am not really a "geezer". I don't do much bling. I have the minimum mobile phone I think I can get away with. The main issue when buying one is - can I buy it for under £100, and - does it last for years? Apps, screen resolution, camera quality and those things do not rate highly for me. So I currently have a Motorola Moto G. Not the latest version either, the previous one. I cannot be a cool dude with a phone like that. On the other hand, I might not cry if someone stole it, or I dropped it into a pond like my Wouxun handheld.

Here is a man with a 8-core PC finely tuned for maximum performance and he cannot tell you what his phone can do. I just am NOT INTERESTED. But you can take it that if EsSense runs on Jim's Moto G it will probably run on any Android phone.

I have location and roaming switched off, so it might drop out a bit.

I keep location and roaming switched off because I do not like spending money on phone charges which could be spent on MORE RIGS, and I do not like "them" knowing where I am at any time. Just because you aren't paranoid doesn't mean they aren't out to get you (and I am paranoid as well).

Does EsSense work on my mean phone with my mean connections? Yes it does. I tried to scan the phone screen in (!!!) which did not work and I ended up photographing the screen which did not really work either...
... but it does show up VHF activity rather well. It drops out when I go beyond my wi-fi zone, but I will try it with roaming turned on. The only snag I find with it... - EDIT - this is working now. Maybe something was wrong with my touch screen. No problems now at all.

Anyway, I like it. It gives all the info I need. It updates itself regularly. It even works on my junk phone. and it is another reason not to buy an iPhone and spend the £££ on antennas instead.

Thanks Allard. Nice one.

As for an update, I posted last week that I was "mildly interested" in the situation then. It turned out to be an variable week when I worked nothing surprising. A bit of F layer activity got me working JT9 on 10 metres, as far as the USA (Texas) and Uruguay. There were quite a few Es openings on 10m which I followed on WSPR. There was one pretty good Es opening on 6m which I missed as it only covered a triangle from Germany to Spain and the Midlands of England. I was about 300km too far North. Fun to watch on Dx Maps though.

The past couple of days have produced interesting conditions on VHF as there have been several solar weather storms but no result here. The K number has been as high a 6, with high wind speed, proton numbers and negative Bz, so you might have expected something to happen. It did, but not at this QTH. Nick, G4KUX, who is about 50km south of me, was working into Sweden on 2 metres but I heard nothing. Just the Northern Ireland beacon on 2 metres via weak aurora.

I have been standing by, but nothing reached me. You can often see an aurora coming in from the East. DX Maps shows stations working each other across the Baltic and then it spreads across the North Sea to reach me. We had this ...
... it looked promising and then ... nothing. Ah well.
As the numbers looked good, and Solarham.com was predicting aurora over Northern Europe, I wondered why nothing happened here (well not in Scotland generally). I have no answer to it, but while delving through the figures I discovered comparative magnetometer readings over the week which show the GOES satellite regularly over-predicting the events.

I won't bother you with the charts now as I need to think about what they mean. I have always found the Norwegian Stack Plot to be the best indicator, and it was right this week. I think that maybe I am getting over-reliant on the GOES predictions when what is happening on Earth may be more important. But something did happen, as that DX Maps shot shows. More thinking needed.

Maybe the next few days will bring the conditions I have been waiting for.

I am pondering another antenna re-working and there may be something on the rig front, so be ready for more nonsense soon.

73

Jim
GM4FVM

Thursday, 11 February 2016

Winter Es plus some more meteor scatter thoughts.

Turned on to find Russian taxis on FM bang on the WSPR frequency - a classic sign of Es.





... more F-layer DX getting in the way  ...


The US Space Weather Prediction Centre said (on Solarham):-

.Forecast...
The geomagnetic field is expected to be quiet to unsettled on day one
(11 Feb) due to slightly elevated solar wind speeds and periods of
prolonged southward orientation. An expected SSBC later on day one may
also cause an unsettled geomagnetic response. An incoming CIR followed
by connection to the positive polarity CH HSS, is expected to cause a
few periods of active levels on day two (12 Feb), with mainly unsettled
to quiet conditions shortly afterwards. Day three (13 Feb) is expected
to experience quiet to unsettled levels as the CH HSS effects begin
waning.


Interpretation. I believe that an "SSBC" is a solar sector boundary crossing (a magnetic reversal) and a "CH HSS" is a coronal hole likely to release a high speed stream (increased solar wind). "Southward orientation" means a negative Bz number (the magnetic polarity of the solar wind which tends to produce geomagnetic disturbances).

"Unsettled" is often the word for those slightly elevated Solar Weather conditions which do not produce a blackout or aurora, but still produce Es. "Active" often means an aurora, which could happen tomorrow but only a "few periods" and maybe not at a time when I can benefit. It may be weak anyway, so I am not holding out much hope. Mildly interested, I would say, is my state right now.

As I write Bz is -5.2 which might be more interesting if the solar wind speed was above 400, but the wind speed is 320. The X-Ray flux is mildly raised and the proton level is flat. So some indicators are raised, but there is not enough to cause the aurora which is the icing on the cake for me.

These are the sort of conditions which I often see reported in the amateur radio HF reports as "disappointing" and anything more active is described as "terrible", even though last time I checked 10m is HF as well. It just means that the predictions are made by HF DX-aholics who seem to feel that nobody in this hobby actually likes propagation research, a bit of Es or maybe even (perish the thought) some VHF. OK, I am a dinosaur, but I still think that VHF has some interest, and one of the main VHF phenomena (Es) is something I can best research on 28.124600 MHz.

I would rather do my listening on 40MHz, but there isn't much there to hear. Even if that was an amateur allocation, the operation of the "FVM equation" (as apparently my scribblings in my last post are now called), would mean that the propagation might be there but the amateurs would not, so I would not hear much anyway. There are a couple of amateur beacons on 40MHz, but they seem to be off the air more than on it. I commend the IRTS for trying to get more interest in 40MHz.

Speaking of bands, I am about to start an "Introduction to VHF" thread here, rather like the dreary data modes one I did before. More scope for me to ramble. I must start with a summary of the VHF bands.

I have been thinking some more since having read Meteor Science and Engineering by McKinley as posted here. McKinley talks a lot about a meteor shower which produced two of what he reckoned were the best displays of the 20th century. He called it the "Giacobinids" (spellings vary). In 1933 and 1946 this shower produced dramatic results, but in other years seemed to fade. It meant nothing to me - I was not around then of course. But I had never even heard of them.

It appears that we now know this shower as the Draconids, as they appear to originate in the constellation of Draco. In recent years the same variability has been noted in the Draconids.

This brought to my mind the potential for some lesser noted or even so far undiscovered shower to produce a dramatic effect. We really only know about the showers which we have already observed by colliding with them. We cannot say for certain that a previous or new comet might suddenly lay down a trail of meteorites for the Earth to cross.

If I understood McKinley correctly, the view in his day was that the variability was down to the nearness of the comet itself to the Earth as the Earth rotated, and thus whether the Earth was going to pass through a tight trail of debris. On the other hand, I have seen a report that suggested that 2012 display was enhanced due to a direct pass by the Earth over the trail laid down in 1959.

Obviously these sorts of factors will change the results we amateurs get from year to year. Each year we do not know quite what to expect. Well-known, historically good, showers may produce little or nothing this year, and may virtually disappear. On the other hand, something new may appear at some other time of year.

We are getting better at detecting near-Earth objects as they approach. This is not easy as many are on very long elliptical solar orbits or are just coming by here once. We now know that there are hundreds of these objects each year. Some of them may leave particle trails which will produce meteor showers, and these may be completely new to us.

I dutifully write down my shower dates into my diary each year. Who knows if something unexpected will turn up this year?

This business is really surprising.

73

Jim
GM4FVM

Monday, 8 February 2016

Es Predictions, Probabilities and Alien Life.

WARNING - strange abstract concept discussed below - deep thought required. Thinking is at your own risk - you never know where it might take you.


Image of a nice big juicy X-Ray pulse as reported by the GOES satellite on 2 February, which had over 50 WSPR spots at GM4FVM over the next four hours.

Geoff, G0LUJ, was in touch with me following my posting about Es predictions. Geoff too has been disappointed by the predictions he has seen.

I have to agree there. What I see passing for predictions are often useless, though I can well imagine that trying to predict propagation might be a fairly tricky task, especially at VHF.

In outlining the link I find between Es and X-Ray bursts I was thinking about understanding the process rather than making predictions, though of course these are related. Geoff raises a good point by saying he was going to try to look for some chance of predicting events. The X-Rays travel from the Sun at the speed of light, and those little bursts I see will be here are soon as they are detected ... almost. The GOES satellites give us some advantage, and then there seems to be an hour or maybe up to two hours delay before the Es occurs. But the link is clear for me to see.

I have seen over 100 WSPR spots on 10 metres after such X-Ray bursts in the past week. Stations regularly featuring include IK1WVQ, IU1DZZ, DK6UG, DB0ZDF, DK1RS, HA9AL - all within a single Es hop. I am not so sure about SV8RV, as he has appeared several times and that is probably a double hop - unusual in Winter (I think). I said I was not going to go on about this apparent linkage, and I won't, but it is interesting for February.

There were also a couple of spots after another feature which seems to be linked - a rise in the Solar-K index short of an aurora. In this case it was K=3 and there was no aurora here. This though may be the often noted "auroral Es" phenomenon which is very welcome but something else. It usually only benefits Northern stations, unlike the other ones which were south of me.

And so, leaving Es predictions aside for a while, I wanted to think more about when I hear Es rather than when it happens. Eh? Well Gianfrance, IU1DZZ, pointed out to me (about "Sporadic E") ..

it's just a conventional name. Not sporadic. It's frequent, but often
 it appears in wrong places for us, or it lasts only few minutes...

That really made me think. Yes, I can see Es almost everyday on DXMaps. But I don't hear it every day. What does this mean? Well, we know that Es is very localised from the viewpoint of the individual ham. From the viewpoint of stations I might work - the DXMaps page "Europe" - it happens pretty well every day on 10m. So, when I see an X-Ray pulse on SolarHam and I look for Es, I have been finding it because the Es cloud just happened to fall between me and Gianfranco and those other helpful stations. But sometimes it must happen and I do not hear it. So what are the probabilities and how can we predict that?

There are a lot of variables here, but I know somewhere else where several unknown variables have been combined into a useful model. Whether a similar model will ever predict anything useful about Es I do not know, but please let me take us down this route.

The model I am thinking of is The Drake Equation. In 1961 Frank Drake was working on a model which would allow us to think about (not necessarily predict) the probable number of extraterrestrial civilisations who might just contact us. This will of course depend on how many of those civilisations there are (which will depend on the number of planets, which would depend on the number of stars and galaxies), but also on what stage of development they might be at and whether they can communicate with us ... etc !!!

Wikipedia says this ..

The Drake equation is a probabilistic argument used to arrive at an estimate of the number of active, communicative extraterrestrial civilizations in the Milky Way galaxy.[1][2] The number of such civilizations, N, is assumed to be equal to the mathematical product of (i) the average rate of star formation, R*, in our galaxy, (ii) the fraction of formed stars, fp, that have planets, (iii) the average number of planets per star that has planets, ne, that can potentially support life, (iv) the fraction of those planets, fl, that actually develop life, (v) the fraction of planets bearing life on which intelligent, civilized life, fi, has developed, (vi) the fraction of these civilizations that have developed communications, fc, i.e., technologies that release detectable signs into space, and (vii) the length of time, L, over which such civilizations release detectable signals, for a combined expression of:

N = R_{\ast} \cdot f_p \cdot n_e \cdot f_{\ell} \cdot f_i \cdot f_c \cdot L
The equation was written in 1961 by Frank Drake, not for purposes of quantifying the number of civilizations,[3][better source needed] but as a way to stimulate scientific dialogue at a meeting on the search for extraterrestrial intelligence (SETI). The equation summarizes the main concepts which scientists must contemplate when considering the question of other radio-communicative life.[3] Criticism towards the Drake equation follows from the fact that several of its terms are conjectural, the net result being that the error associated with any derived value is very large such that the equation cannot be used to draw firm conclusions.

I am no Frank Drake. I do not have the intellectual ability to even really understand what he has proposed, but I get the general idea. I think his approach could be applied to understanding (but not necessarily predicting) Es.

In 1961 Frank Drake was not really proposing to put actual numbers into the elements of the equation, he was outlining the broad parameters which would apply. Estimates could be made or not, but at least you were considering what factors to include. Since then of course, we have found that almost every star we look at has several planets, so we are beginning to get some feel for the likely numbers.

This is a bit off the track of Es predictions. Still, what I was thinking about is, what are the factors we would need to take into account to see whether Es would occur HERE (GM4FVM, on a band I listen to, at IO85, when I am awake ...)

So without the equation actually being written at the moment, what factors arise?

Well the probability of Es being heard by me will depend on (at least):-

1) time of day and time of year

2) the formation of ionisation in the Es layer, which in turn would depend on:-
- energy from the Sun (for example solar heating of the atmosphere [perhaps mostly UV] but also transient bursts such as X-Ray and proton bursts)
- solar wind as in auroral Es (speed and density being factors?)

3) location of the ionisation cloud
- within the arc which brings a possibility of a contact here, or elsewhere (distance and direction)
-  in relation to countries which have amateur allocations in the band in question

4) the probability of there being an amateur within the suitable region (operating, operating on the same band, with suitable antennas pointing the right way, ...)

I have not formed this up into an equation as I think it is fine like this while I ponder over it.

I have not even considered "double hop", where you have to have two Es clouds and that brings in some very complex geometry and probabilities.

One of the major questions is not "is there Es now?" but "is there Es somewhere where I can make use of it"? Gianfranco is right - there is always Es.

As I said earlier, there is Es a lot of the time. Often, the position of the Earth on its rotation means that is overnight here, and Es is benefiting amateurs on the other side of the world. However, a lot of Es in Europe is not going to benefit me either. Only Es clouds located in a wide arc around 600 - 1000km round my location from about 60 degrees to about 200 degrees ever produce much Es here.

If they are too close I can see EIs working stations on the cluster. If they are too far away I see Russian broadcast stations being received in Sweden. If there is Es in the other 220 degrees I rarely even know about it. Yes, I have worked Jan Mayen, Iceland, Newfoundland, Azores and so forth, but those are specks of land in those directions with almost no amateurs. There are vast swathes of Atlantic Ocean with no stations within Es range. Russia does not have 6m, Switzerland does not have 4m, Africa has very few amateurs these days and even fewer on "my" bands ... the list of blank spots around me multiplies all the time. There must be an awful lot of Es which I can never detect.

Here is the point. Predicting Es is not really the key to this. It is possible to predict Es more or less every day. Predicting where the Es clouds will occur is the art. Will they occur somewhere which allows me to make a contact? Will there be anyone there even if the band does open?

By some strange quirk, doubling the number of amateurs, especially in certain parts of the world and certain bands, would produce a lot more reports of Es, though the actual occurrence of the phenomenon would not have changed.

Please excuse this flight of fancy. I think it might take us somewhere in understanding the prevalence of Es. Until we realise that the factors affecting us hearing Es are different from those deciding how much Es there might be, we will never understand it. Just as Frank Drake tried to tease out - there may or may not be a life form out there, but whether we ever contact them depends on a lot of other variables.

On the other hand, there may be no intelligent communicating life forms beyond the Earth at all - which is what I believe. Proving it is a bit more difficult.

Mind you, I seem to hear some Aliens on the bands sometimes.

73

Jim
GM4FVM
P.S. I am an Alien here in Scotland - I was not even born here.



Tuesday, 2 February 2016

IC-7100 low SSB output - a surgical solution

News from Greg SP3RNZ.

He has heard from SV0CL about a modification to increase the output power on SSB for the IC-7100.

I have reported before that my IC-7100 is low on power on SSB, but not on other modes.

I have not tried either of these mods as I already have an outboard set-up which I think I will stick with for now.

BEWARE - modify your rig at your own risk!

If I was going to try either of them I think I would try number "2".

They are interesting on two counts - they are not big modifications - and it shows that many minds have been working on this problem.

Greg's blog is here http://www.sp3rnz.blogspot.co.uk/

As Greg points out, these are not official Icom modifications, and he and those who designed them cannot be responsible if any damage results. Come to think of it, I have not tried them and I cannot be responsible for any damage caused either.

Before you tinker with your rig remember that you may invalidate the warranty or do some damage. On the other hand, radio amateurs are famous for working on their own equipment.

Here are the two pages on Greg's website which deal with the modifications. Note that you should only do one, not both. The SOFT one looks best to me. See also the comments from those who have done it.

Here is the main post:  http://sp3rnz.blogspot.co.uk/2016/02/breaking-news-icom-ic-7100-low-ssb.html

Here is the addendum; http://sp3rnz.blogspot.co.uk/2016/02/icom-ic-7100-low-ssb-power-modification.html

Both the suggested mods look fairly straightforward and they look reversible provided nothing else was affected.

Thanks Greg and everybody involved.

73

Jim
GM4FVM

Monday, 1 February 2016

Storm Gertrude damage - not too bad, thankfully

I seem to have got my yagis in a twist.
Oh dear, what a stoochie. They are both supposed to point the same way!

This Winter the UK Met Office and Met Eireann jointly started to name storm-force events. This one, being the seventh to be named got a name beginning with G, so it was titled "Gertrude".
This is Gertrude passing north of Shetland, dragging winds across Scotland (BBC News Scotland website).

All the usual signs were there - the railway ground to to a standstill due to the overhead lines being down, and trucks were blown over on the A1, closing it. As so often, Ayton was "cut off". Well, not really, despite blown down trees you can usually work your way round it. Blown down trees are not such a problem here as further South - most of the weak ones have already been blown over. We get so many events that we do not get the "once in a generation" tree felling which occurs elsewhere. What gets blown over are trucks and vans.
Peak winds noted in Shetland were well over 140km/h, here we had gusts of about 105km/h (photo BBC News Scotland website).

I did not actually realise that the 2m antenna had become loose until I went out to wind up the tower for some meteor scatter. It was still pretty windy and I decided not to risk raising the antennas above the ridge tiles of the house. The antennas are quite well protected when the mast is wound down - but still one worked loose.

Next day I tilted the tower over and managed to get the antennas back in line. The antenna bracket was well tightened and it had ripped a gouge out of the aluminium pole where it had torn loose. It had fallen about 100mm as it twisted round. I decided to leave it at that height and tighten it there rather than move it back to where it had left tear marks.

At this point the bracket supplied by Wimo was showing its weaknesses.
I remarked at the time I put it up that this antenna was rather lightly built, (link click here) when I was daft enough to say --
it is beautifully made and I doubt if I will have any problems with it in the gales.
Well my defence is that the antenna was OK, it was the bracket which gave me the trouble. The photo above shows that it is a single U-bolt design, which I never really like (the Vine 4m beams also have this type of bracket and I have remarked before how poor they are).

After I had fixed it back in line I noticed that the 2m beam was now pointing too much skywards. It is often said that a couple of degree upwards mounting is good for meteor scatter but this was too much. So even though I had tightened the wing nuts fairly tight I tried to straighten the boom. And once I did that that, the mounting loosened again. I got about two more turns on the wing nuts. That might explain how it came loose in the wind.

Anyway, both Wimo and Diamond use wing nut fixings. I am not absolutely against them, provided that the nuts are well made. Even though Diamond say "do not use tools to install this antenna", I do give the wing nuts extra tightening using a pair of pliers. I did the same with the Wimo, both last time and this time. You run the risk of sheering off one side of the wing nut, but you can feel happy that the antenna is well tightened up. I have a box full of wing nuts; they are not hard to replace. I could replace them with conventional nuts too.

So maybe I need to fit a better bracket to the Wimo. They do not seem to quote a maximum recommended wind speed, but they do quote a wind loading figure for 160k/h (!!). What I do not want is for the antenna to "windmill", in other words work loose and start turning round on the mast. Not only does this cut into the mast, the co-ax winds up and is usually damaged.

Perhaps I need to think again about why I mounted the antenna at the weight balance point. That means that the wind-free load on the rotator is fairly evenly balanced, but it probably makes the wind act more strongly on the front of the antenna. If I moved it to the wind balance point there would be less turning force in a gale at the cost of more strain on the rotator. But I do not know where the wind balance point is (I would have to guess).

The boom catches more wind than the elements as it is much thicker square section. The wind balance is probably nearer half way down the boom. In the photo above the joint in the boom is about half way, so I could easily move the bracket 200mm or so, which might make all the difference, and still leave the weight more balanced than putting the support right at the centre. Would that stop it whistling in the wind too?

Now that Gertrude has passed, say hello to Storm Henry.
The black areas represent 14m (48ft) swells in the Atlantic (magicseaweed on the BBC New Scotland website). Fortunately it hits the West Coast of Scotland first so our swell should not be so bad, but the winds will still be quite something.

It was only yesterday when I fixed the 2m beam straight, and Henry is due overnight tonight. Whilst Gertrude brought 105km/h wind here, Henry has been revised down (!) to 113km/h.

Several rail routes are to close after 16:00 and road closures have already been announced.

Let us see what happens next!!!

73

Jim
GM4FVM