It's been unusually calm this week, with light winds and some warm sunshine.
I decided to have a go at a 7MHz inverted-vee antenna, which is very useful in only needing one support.
40m is go!
Initially, the wires were cut at 10.1m per leg, which proved to be too long, as expected.
With the apex at about 8.5m, and the dipole wires sloping down to about 4m above ground, the correct length of each leg proved to be 9.7m, yielding a SWR no greater than about 1.2:1 SWR across the whole band, as the following (much too wide) scan with the SARK-110 shows:
There were not so many stations active mid-afternoon on 7MHz, but I did work a very strong PA station that was using 500W to a dipole (easily defeating a damned tuner trying to interrupt proceedings):
I also ran about 20 minutes' worth of 200mW WSPR, just to get a quick idea of relative performance. The plot shows my 200mW was doing better than the comparison station's 5W into a half-size G5RV, which is very pleasing.
I have never been very interested in 2m FM, other than for DX and satellite operation. One reason is that 2m in the UK tends to be populated by people who don't engage in very interesting conversations. It's also true that there are some rather dodgy people hanging out on 2m - people you really want to avoid.
All that said, 2m is, of course, potentially very useful for local contacts. I know of a few lonely, elderly people who find the regular morning ragchews keep them going, and that is a very valuable thing indeed.
Reached a dead end.
But the sad fact that, by 2018, 2m FM in my area, which, because of its elevated and clear position, stretches out to Northern Ireland, Southern Ireland and western England, is all but dead. The band was always populated by just a handful of regulars, but whose health has now deteriorated or their lives ended altogether.
Whilst I could never say that I will remotely miss the kinds of QSOs that were to be had on 2m, it is obviously very concerning that 2m seems to be the canary in the coal mine for things to come for other aspects of amateur radio.
Well folks, it's rarely wise to generalise about band conditions, but we seem to have reached rock bottom these past few days.
Whilst the WPX contest provided an astoundingly high activity rate this weekend, conditions on 14MHz remain generally pretty poor. That band takes a long time to wake up in the morning, there is precious little indication of long path propagation, and beyond 18MHz, there is not much reliable activity.
Reaching the bottom. Image: Royal Observatory of Belgium.
The solar cycle is either at or very close to its minimum now, and predicted by the Royal Observatory of Belgium to begin rising as soon as late summer 2018. Certainly, we can expect solar activity will remain very low until the end of 2018, at least.
I have to admit the lack of activity means I am not spending as much time on the radio as once was the case. That 'slack' is being taken up with tidying up developments at the 'weekend shack', and the chaos of also trying to move house.
Global band activity at 10:30UT today. Image: DX Heat.
Turning to something other than radio is not altogether a bad thing. It can become, and is for many of us, a bit of an obsessive habit that is ever-present in the home. Not that it's a bad habit, but it can become more like a lifestyle sometimes.
Still, summer is now sweeping in after the terrible winter that started with ex-Hurricane Ophelia, and ended with two brutally cold spells of weather following a sudden stratsopheric warming. After all that, simply enjoying the great outdoors, with just a bit of 50MHz operating, will see us through the last breaths of this solar minimum.
If you ever come to build antennas, you might well find yourself wondering how to physically join two elements together mechanically, whilst keeping them electrically isolated.
I revisited this problem this week because I wanted to make use of a successful multiband, end-loaded vertical that can see useful service at my alternative operating site. The antenna is a twin-fed, homebrew version of the I-Pro 'Home' antenna.
Having used round timber brush handles for a temporary test run, I found it almost impossible to remove this from the aluminium tube! The timber had been outside in the weather for perhaps four years or so, and it was to be expected it would now be rotten.
The only way I could get the timber out was to apply strong heat from a butane gas torch. This worked remarkably quickly, the wood just falling out after a minute or so.
Remarkably, when I cut through the timber, which was a hardwood, I found it hadn't rotted at all. So if you can find the correct wood, this coupling could last for a long time.
But I had now embarked on changing things. The alternative material I have tried is Delrin, a plastic that is meant to be suitable as a replacement for metal.
Delrin has interesting properties, not least of which are its mechanical strength and remarkable heat resistance. This latter property became apparent as I tried to figure out how to insert a Delrin rod into aluminium tube that was very slightly (about 0.2mm) smaller than it. Superficially, Delrin looks and feels like nylon.
If you like mechanical engineering and 'slow TV', this video is moderately interesting. Having seen a professional engineering friend killed by the simple act of polishing a metal tube on a lathe, I very strongly recommend you don't clear waste from a turning lathe as appears in the video.
Without a lathe, all I could so was to try careful, even sanding. This worked quite well, enough to get the Delrin rod to line up properly inside the opening of the tube, but no more.
I then tried heating the aluminium tube quite strongly, which eventually causes the Delrin to start softening. It doesn't melt as such, with only the slight excess width being sufficiently softened, a bit like thick tar, to be pushed aside and allow the rod to fit. Even then, it takes quite a lot of physical pushing to get it to go in.
Perfect friction fit!
I found that after cooling, the Delrin could be removed easily by hand, but the fit with the aluminium was perfect, with no 'play'. This is very useful to me, because there is no need to drill holes through the Delrin and aluminium to secure the fitting; friction is more than enough. It also allows easy assembly and dismantling without tools.
The end-loaded vertical is quite top-heavy, and puts a reasonable stress on the Delrin rod. But tests show it is easily capable of taking the load, although guying is needed in moderate to strong winds.
A nice warm day today, and a quick chance to finish some wiring and test out the system on SSB.
Using a 1/4 wave elevated vertical, conditions at 14MHz were pretty good compared with a few days ago. I managed a contact with WD8CCC on 60W PEP, and a very strong contact with Ukraine. The shack walls and ceiling are a little too lively, producing a distinct echo in my audio, but some plastic foam sheet or old carpet will sort that out!
The 100W panel was brought into action as I operated, and proved to keep the battery in very good condition.
I have yet to choose a high quality charge MPPT charge controller, using a second-hand waterproof PWM unit from Photonic Universe to get me going quickly at low cost. I am have also not yet fitted ferrite rings to reduce cable-mediated RFI. I am happy to say there is only a very weak level of pulses during rapid changes to solar intensity (when clouds drift in and out), and cause no problem at all. In steady light, there is no discernible RFI.
For more local readers, don't worry - no radio or other expensive equipment is left in the hut. You may also come across a shotgun-carrying farmer.
If you like ham radio, there's never long to wait before you need to repair or replace antenna connections.
For many, and that certainly includes me, it is often easiest and cheapest to make connections to, say, a balun by using ring or spade connectors that are widely sold for automotive and general purposes.
These connectors are very good, and usually made of plated brass or similar alloy. They do, though, have poor mechanical strength, so any wire tension has to be taken by a relief loop, and not the connector. The connectors have good resistance to weather, but do corrode.
Last week, I was sending some signals on 10MHz with my half sloper for that band, connected to a 1:1 balun at the tower. This wire is normally very well-behaved, but had recently started to produce brief SWR spikes, although these were not to very high levels.
The wire I used for this initially experimental antenna that became permanent was quite thin, multistranded stuff, but with a very heavy duty PVC coat. I decided to change it, as SWR spikes usually indicate the wire starting to come apart within the PVC.
Probably OK, but stainless won't suffer this corrosion at all.
I haven't bothered checking if the wire really was decayed, but one thing is clear: the ring connector suffered quite a lot of corrosion after a winter out in the windy, salt-laden air of coastal Wales.
The part protected by a washer and nut was quite clean, but there was also a small part where insulating tape projected into the washer area (on the other side to the one in the photo). This could have contributed to or caused a momentary loss of connection. For some reason, I hadn't used the stainless steel ring connectors that I already had.
So if you are planning on an antenna repair or replacement as the weather warms up, make sure you use stainless connectors throughout.
Thanks to my blogger colleague Bas, in the Netherlands, I have been getting to grips with APRS Messenger software for HF recently.
This looks like an interesting new addition to the range of activities with HF radio. But I am not really sure what the software is actually for. I guess it is somehow 'disaster'-related, but I am not a US-style Prepper, and don't expect ham radio will save us from annihilation if Kim Jog Un presses his little red button. There will, after all, be nobody left to communicate with. Also, nuclear detonations are known to severely disrupt the ionosphere to the point where propagation will be, at best, tough.
This is what N8PJ, who runs PACTOR.com, has to say about emcomms:
"The
continued claims PACTOR-4 serves ECOMM (Emergency Communcations) is a
ruse, a falsehood. There are so many alternate 'free' commerical
communications paths
available that it renders the argument that "Ham Radio is a viable
alternative for emergency communication" a joke. Much more reliable
communications alternative are available today."
Never mind. I still have my rig...
For now, the biggest problem with APRS Messenger is that it seems rather deaf. I have seen a few signals on the waterfall, but over three days or so, I have only seen the software decode two stations - OH8STN (once) and K1CKK multiple times. Including the US station, this seems to be good going, compared to many, who don't seem to be decoding much at all.
The problem seems common to most. A discussion group tells of the troubles thus far with this, admittedly experimental and under-development program. Another blogger also has tales of woe.
UPDATE.
I've uninstalled the software, unsubscribed from the related Yahoo! group, and left the author to sort the program out, which he now admits is "not 100%".
From his postings online, he seems to expect everyone's rig will be so well frequency calibrated that they might match a physical standards laboratory's levels. My rig is +4Hz out on 10MHz, +2Hz out when averaged across all bands.
Any mode that, unlike the plethora others, demands absolute accuracy from what are, in the end, consumer-level electronics, is missing the point and doomed to failure - which is what Messenger appears to be undergoing right now.
And why, pray tell, would I bother wasting time on a mode and software that has little purpose and doesn't anyway work, when I can turn to countless other modes that do?
After weeks of getting the place ready, and a final connection to earth, the getaway shack is finally producing some warps in the fifth dimension (if you subscribe to Kaluza-Klein theory and its string theory derivatives!)
Using a 1/4 wave vertical and only 40W PEP in very poor conditions, I managed to work EA88ARI/P, very efficiently working a big pileup as he activated La Palma peak VGTF-053, Fernando Porto, under the DVGE scheme, the Spanish equivalent to IOTA. Radio is a great way to practice language skills, and I never pass up a chance to speak Spanish, though this recording is only of the received signal, not the QSO:
After the QSO, I connected the 100W PV panel that is for temporary, but more rapid charging during operations than the permanantly-connected (but switchable) 10W trickle charge unit produces. Even in very dull conditions, this was doing a great job of taking the battery back up to full charge in just a few minutes. Nice also to see that there is no discernible RFI, at least on 14MHz, from the PV system, even without any ferrites installed as yet.
This is how things now look. It appears pretty rubbish on the outside, but is structurally sound and remarkably warm inside, thanks to a thick heat-absorbing concrete roof, and water only a few centimetres below the building.
Over the past week, it has been, for the UK, remarkably cold, with a very strong and days-long wind of up to 90mph in places.
In readiness for the wind, I had quickly taken down my 1/4 wave vertical for 20m a day or so beforehand, laying it down on the side of a ditch, where I thought sheep would not get at it.
Baaaa!
After the storm had subsided, I went back to the marsh site to do some work on the shack.
Apparently, green plastic-coated kevlar reinforced antenna wire looks like a tasty piece of long grass to sheep, who promptly took to nibbling on it! The brutally cold conditions also meant the sheep took shelter against the shack. I had fixed the small solar PV panel low down, so as to avoid long lengths of vertical RFI radiators. But the sheep found this very interesting, and had a very unsuccessful attempt at eating that, too!
Sheep's teeth have no problem cutting through kevlar, as this (very rubbish) photo of one of my radials shows:
Tasty. For a while...
Still, this is what field activity is all about, so a quick attachment of some spade connectors, soldering the wire and crimping onto the kevlar and coating makes for a perfectly good connection.
Trickle charge PV panel (10W peak), now a bit higher!
I've now fixed the trickle-charging PV panel higher up, where it should be out of reach even of cattle, which will no doubt appear in the fields soon. The main, 100W panel, only goes out during operation, or after a heavy period of use.
