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");
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

QRP Labs Ultimate 3

Some months ago I was planning an afternoon at our local Fab Lab, partly to help raise their profile and partly to introduce some club members to the easy to use laser cutting services they have. We designed an profiled a case for the QRP Labs Ultimate 3 WSPR transmitter.

It occurred to me that I haven’t really shared the experience having been enjoying myself at the 24 du Mans race, celebrating my parents 50th wedding anniversary and having a birthday. None the less, its time for a catch up.

The U3 is a fairly simple build, in its basic form takes about and hour and a half to build and test. Start adding the various extras like a switchable band pass filter (for 5 bands!) and a gps unit and the time to build, well builds up. The kit isn’t complex and doesn’t use smd’s (although I’ve never understood the fear of them – whilst my eyes are still ok) and there’s only 4 coils to wind for the basic version.

The biggest issue was how to box it up. After trying various configurations we settled on a very simple front and back panel design, Others, like the desktop version or ones with castellated fixings either looked a bit cheesy or were hard to put together and prone to breaking. A simple 2d CAD sketch is loaded onto the machine, plonk in the materials and you’re away. It couldn’t be simpler. Anyway here’s the semi finished product. I need to do something about the spacers as they look awful but its nearly there.


U3 small

Coding for the challenged

Ever since the dawn of time coding has been a foreign language to me. I pick up bits and pieces but largely it gets forgotten or lost.

Tonights issue is about interrupts and debouncing buttons. What better thing to do whilst listening to the 6m white noise contest (also known as vhf from my qth).

The idea is simple. I made a shack clock from a gps and an arduino. I made it tell the time, tell me the position I’m in (no I don’t mean like that) an calculate the locator square. Now then all I want to do is link these together with a simple button press. Press the button and it changes from one function to the next.

Holy arduino, this isn’t straightforward at all. Buttons need debouncing and interrupts don’t like this or that. I feel a long development time in my future…still there’s not much on 6m and 2 contacts in the first hour isn’t going to win me any awards.