What did YOU do on World Amateur Radio Day?

I set-off yesterday afternoon to do a spot of 15m portable from the lakside. Though conditions turned out to be fairly poor, I had one extremely exciting and unexpected contact - with a 6 year old boy and his father!

15m from the lake on WARD.

 

I came across the boy, who was busy saying 'hello' from a distance, with an outstretched hand. I gave him a big thumbs up. He asked what I was doing. I told him I was sending signals to the other side of the world; would he like to see the radio?  'Oh yes!', came an excited reply. His father was nodding his thanks for being kind.

I opened the silver box. He was amazed. I showed him the simple wire we use to send the signals. 'Can you turn it up to two...million?', he stuttered. 'Sure', I said. 'I can turn it up a little bit more than that, even'. 'Waaaw', came the incredulous response.

I then got rewarded for my effort by being shown a series of toy metal cars he was carrying in his pockets. 

Maybe one day, he'll remember the meeting, and try radio for himself?  Let's hope so.

Amazing 6m TEP

I wasn't at the rig when this remarkable 50MHz FT8 signal, at an amazing -5dB SNR, was received (on a mere sloping delta cut for 30m!) from ZS6NJ at 9369km today, which rather overlooks the other, 6 minutes earlier reception of TT8SN, at 4903km.

Seems to have got social media pundits quite excited. 

Wow!

Intermediate licensee challenges laws of physics.

I'm always surprised that so many people seem not to realise that using a horizontal antenna next to sea water, whilst hardly unlikley to produce good results, is nevertheless going to produce vastly reduced performance compared to using a vertical. At least insofar as our usual quarry - good DX - is concerned.

This 1952 graphic (based on real measuerements, not models), and any number of modern versions, is all people like 2W0YMS need to absorb. It's not difficult. Fields depicted over perfect ground (i.e.similar to seawater).

 

So I idly commented on the latest 'holiday-style' DXpedition that were merrily using a horizontal dipole, on Twitter yesterday.

I was a bit surprised to find a fellow Welsh amateur pipe-up with a rather odd - and wholly pointless - response, which clearly indicates his belief that the horizontal vs. vertical assertion is wrong. Oh, and that I appear to buy antennas "off the shelf" (I invariably build my own antennas, and never bought a vertical HF antenna):

 

Well, it takes all sorts. Even ones who are not particularly adept at punctuation, or being a bit circumspect about what they commit to the public sphere.

For those who are more interested in learning than being pointlessly abusive online when your argument is fundamentally incorrect, you can try this site by the Royal Signals ARS, as but one of very many you will find online and in books.

Given the choice between people like the late Les Moxon, G6XN, and an upstart like 2W0YMS, I know which one I will take notice of. Maybe a copy of the ARRL Antenna Book and/or HF Antennas for All Locations for you next Christmas, Mark?  You might just learn something and even go try it out for yourself. 

Going underground with 2m FM!

A meeting of interests over past weeks meant that I had to build a moderately-directional antenna for 2m FM, to be used with a Baofeng UV-5R III handheld.

The interest is in trying to add some evidence to the expected existence of a shaft, roughly 70 feet (21m) deep, that was dug to assist the driving of a drainage adit for the mighty Penrhyn slate quarry, for many decades the largest slate quarry in the world. It was also the site of what remains the longest-ever dispute in British industrial history, a strike lasting between 1900 and 1903.

Penrhyn old quarry, ca. 1970s, before work stopped and water flooded the lower levels.

 

Penrhyn old quarry today. Image: RCAHMW.

Started around 1849, the adit is 1.9km long, with a fall (slope) over that distance of only 3.7 feet (1.1m). It was driven by Mormons who had previously worked in the coal mines of South Wales. They took 2 and a half years to complete their amazing work, and then left Wales for Salt Lake City in Utah, a focus of Mormon culture.

A remarkable (and long!) feat of human effort - and a fascinating journey through time and slate beds!

 

The direction of drill holes, when surveyed fully and plotted out, provides compelling evidence for the existence of shafts - which were expected to be necessary in the contract for the works - in that there are slate arches from which the direction of driving the adit goes off in opposing directions. 

Shoving a mobile phone camera above one of the arches showed some, but not especially clear evidence of a void above one of the arches. So I thought that, in order to conclude several months of work down there, I'd try using VHF handhelds to see if the signal received on the surface might vary when a transmission underground passed under the putative shaft.

Arch number 9, steel-lined and potentially problematic for 2m radio!

 

Unfortunately, the best and most easily surface-located position of a shaft has a steel-lined ('tubbed') roof. This, its concave form, and its radius, means that it is almost perfectly suited to bounce any signal sent from within the arch right back to where it came from, and attenuating anything getting through!

Luckily, another proposed shaft location has a slate arch, so this will likely be much better to try, albeit more difficult to locate on the surface to position a receive antenna. We'll see if it works in a few days' time.

Easton and Amos (1859) water pressure engine, using only a head of water as an energy source, to pump water from levels 137 feet below. This emptied its water into the drainage adit.

 

Due to size, weight and robustness considerations (underground activity is very harsh on any equipment taken in), I opted for a 20mm PVC tube-based Moxon. Moxons are a bit fiddly to make, but not too bad.

There are a lot of plans online for this antenna. Sadly, a number of them haven't paid attention to what they were doing, with all sorts of wrong measurements, some not making mathematical sense, written-up for all to be confused!

Simple, a bit fiddly to make, but cheap and effective!

 

I went back to basics, and used an online calculator. This proved accurate when using enamelled hard-drawn copper wire of about 1.2mm diameter. If you use plastic-coated stranded wire, your measurements may well work out differently due to velocity factor variations.

So, if you want to save some time, and you are looking for FM-range 2m operation in Britain, then here are the measurements that worked:

Long arms for radiator and director, two of each per element = 318mm

Short connectors between element centre junction boxes and handle junction box = 80mm

Radiating element, total single wire length needed = 91.2cm - cut this in half for the dipole elements.

Reflecting element, single wire length needed = 99.6cm.

I made small loops in the ends of each wire so that a thin cable tie could be used to secure and adjust the radiator-director separation. This was 22mm in my case - a bit of trial and error is likely to be needed for each build with this dimension, which is why cable ties are so useful.

 

Very pleasing outcome, plotted by the RigExpert AA230 Zoom analyser.

After a bit of messing-about making sure it was all fairly symmetrical, and winding an air common-mode choke, the analyser saw below 1.2:1 SWR across the FM part of 2m, and below 1.3:1 for the entire 2m band, with a real impedance of ~43 Ohms, and an imaginary component of +2.1 Ohms at 145.500MHz.

 

Let's go DXpeditioning, 1947-style!

A post over on Twitter recently provided considerable food for thought about the lack of diversity in ham radio today, let alone back in 1947, when the associated video was made.

The reality about ham radio is that it's a hobby that developed in Anglo-Saxon societies (Britain and its colonies, mostly). It was almost entirely represented by white men - because only men were expected to have any interesting hobbies back then. 

 

The video is of its era, but still quite upsetting. Black men always appear doing the work, with white men, dressed in white, so as to highlight the difference, always look on in domineering, overbearing fashion. 

Colonial whites (skin and dress), folded arms and black skivvies. The natural order of things, as was then believed (and ruthlessly enforced).

 

Let's all point at the black man with a funny hat.

Today, the story is not very much changed, it is sad to say. Black people are still excluded, just as in the magazine cover, where the local man is outside, amongst the trees, whilst the white man, in colonial expeditionary attire ('safari' hat ready for another colonial 'mission', on the amp), is inside, amongst the modern radio equipment.

It's all very sad. More so, because white people of today don't really seem to see what's wrong with all this stuff.  And let's not forget, these kinds of scenes, below, were commonplace under apartheid in South Africa until the early 1990s.

Ham radio in the news - but not in a good way.

Oh dear!  This won't help us:

Definitely not political.

'YL Maria' (YU3AWA) has decided to tell us all how apolitical amateur radio is by, erm, spouting-off about an awful lot of political stuff. Perhaps it's better I don't add any comment to that...