What to do during a contest

With the exception of the UKAC events, weekends are the only time I get on the radio really. I occasionally sneak on during the week but it generally attracts a groan from ‘er indoors. This weekends CQWPX contest is a great opportunity to chase a bit of DX. I got my first and so far only VK contacts from home with my homebrew loft mounted Cobwebb during a contest so I can’t complain.

But what else is there. Well apart from the CW portions of the bands there are other things to do on the air. One of them is something I’ve never even looked at before Wefax.

Normally my weather information comes from t’internet nowadays and maybe this kind of thing is a bit legacy and perhaps not long for the airwaves but I’m sure it serves a purpose for shipping and perhaps far off places.

So how do you ‘do’ Wefax? In my case I tuned to 8,039.100 USB (Have a look here for a good primer and the frequencies and schedules are here) with the trusty Angelia SDR and coaxed the audio in fldigi with a less than ideal set of patch leads and a rather noisy Soundblaster USB souncard. The Angelia is a great receiver so it gave the best chance for this compromised solution. Fldigi will decde Wefax for you so its just a case of selecting the Wefax mode and aligning the signal on the waterfall, nothing to it.

Wefax

After some awful screeching and scrawing that reminded me of when fax machines were in offices and hey presto images started coming through. Adjusting the slant and horizontal alignment is easy with fldigi and as you can see the raw images are pretty good.

fldigi

And here is the output. I’m guessing its going to rain!

wefax_20150329_115140_14070000_ok

 

So if you’re thinking that SSB contesting isn’t for you and you’re at a loss as to what you might want to do with your expensive rig, then have a scout about the bands outside of the usual ham bands. You never know what you might find.

Rockmite

As I’m moving towards CW as an operating mode I took the plunge and bought a Rockmite kit from Kanga. Lets just say its not working quite as I had anticipated. This time I was very careful to look at the various instructions. Lid everything out and then checked every component as I assembled it.

2015-02-28 18.51.57Next time I’ll throw these things together in the usual manner. I might have a bit more success. Power on and I get little in the way of audio, a gentle hiss but not much else. So troubleshooting has to begin. Fortunately there is quite a bit of help for this but to be honest I’m not holding out much hope as I did such a thorough job of checking the first time round. Must be a faulty (insert component here) ;-)

 

All good fun and not as if the world will end if I have to spend some time on it.

Solder fumes

Mention Health and safety and its likely you think of some Muppet decides that children need a suit of armour to play conkers (for those not lucky enough to have tried to make a horse chestnut seed the hardest material known to man, have a look here). Back to the point. I’m talking about looking after yourself in your hobby.

Ham radio has some pretty high hazard activities. High voltages, antenna’s on towers, climbing on roofs etc. Recently I’ve been soldering a bit more. Whilst its not likely to be particularly harmful to occasionally sniff in some fumes its probably not going to do me much good either. So I might benefit from a solder fume extractor.

I understand that the technical terms (and we all love a technical term) is local exhaust ventilation or LEV. Still doesn’t sound too complex and thankfully it doesn’t need to be. A fan that sucks and a filter is pretty much all you need, it seems. So do I really need an industrial scale extractor? probably not. So as an experiment I’ve bought a £5 extractor from eBay.

Its an mdf laser cut body with a 12v (computer?) fan. It takes 5 minutes assemble and may or may not need some PVA to hold it all together. I say might as mine was a good tight fit so probably won’t need it in the short term but as it gets bashed about on the workbench it might need some help to stay together.

The extractor is basic (what do you expect for £5) and didn’t come with any filter media. So a suitably sized filter will be needed. Perhaps the same activated carbon you get for cooker hoods would suffice, will need to be sourced. I dare say just sucking it from one place to blow to another isn’t really helping matters.

I could measure flow, compare against standards, determine filter abatement. I say could, because clearly this hasn’t been designed with that in mind and how would that really help? The video below shows you how effective it actually is.

So the conclusion. The hazard associated with occasional solder fumes is probably quite low and the risk is also probably quite low. But a simple device, like this, has the opportunity to remove the fumes from the workbench and at the very least stop them going in your eyes. That can’t be bad.

Here it is in action. Distance between tip and fan is approximately 10cm.

p.s. If you’re really lucky you can hear my daughter homebrewing in the background (what she is homebrewing is anyone’s guess)

Maidenhead Locators

Locators, or as us Brits call them, Maidenhead locators. Named after a town in Berkshire that isn’t close to the meridian but held a meeting by a bunch of VHF chaps in the early 80’s. In fact the now de facto method for looking something up (Google & Wikipedia) give us:

‘The Maidenhead Locator System is a geographic co-ordinate system used by amateur radio operators. Dr. John Morris, G4ANB, originally devised the system, and a group of VHF managers, meeting in Maidenhead, England in 1980, adopted it. The Maidenhead Locator System replaces the older QRA locator system with one that is usable outside Europe.[1]

Maidenhead locators are also commonly referred to as QTH Locator, grid locators or grid squares, despite having a non-square shape on any non-equirectangular cartographic projection. Use of the terms QTH locator and QRA locator was initially discouraged, as it caused confusion with the older QRA locator system. The only abbreviation recommended to indicate a Maidenhead reference in Morse code and radio teleprinter transmission was “LOC”, as in “LOC KN28LH”’

But more to the point how do you calculate one? Easy if you know Perl (apparently – thanks again Wikipedia)

#!/usr/bin/perl -w
# (c) 2012 Chris Ruvolo.  Licensed under a 2-clause BSD license.
if($#ARGV < 1){
  printf("Usage: $0 <lat> <long>\n");
  exit(1);
}
 
my $lat = $ARGV[0];
my $lon = $ARGV[1];
my $grid = "";
 
$lon = $lon + 180;
$lat = $lat + 90;
 
$grid .= chr(ord('A') + int($lon / 20));
$grid .= chr(ord('A') + int($lat / 10));
$grid .= chr(ord('0') + int(($lon % 20)/2));
$grid .= chr(ord('0') + int(($lat % 10)/1));
$grid .= chr(ord('a') + int(($lon - (int($lon/2)*2)) / (5/60)));
$grid .= chr(ord('a') + int(($lat - (int($lat/1)*1)) / (2.5/60)));
 
print "$grid\n";

But what happens if its all Dutch to you (It is to me)?

Well I put together a simple spread sheet that does the calculation. Its nothing special but deciphering what several different people have put into explanations that include adding your birthday, taking away your dogs maiden name and that kind of thing. Hopefully it’ll help you understand where those numbers come from and how to calculate them. So help yourself and if it doesn’t work then fix it and share it ( I tested it with 3 locators and lats / longs and it seemed to work). I also learnt a few more things about Excel so its all handy.

Here it is then