One for the Amateur Radio guys, especially QRP (low power), but I'll explain any tech terms for those who are interested. It doesn't seem very bushcrafty at first but read on...
If you have no interest in mobile communications or amateur radio, stop now as this is going to bore the pants off you.
Well, I got rained out of the hills the other day - exceptionally wet, consistent downpours and increasing risk of hazardous solo stream-crossings turned me back after one night as I really wasn't enjoying it anymore. Frankly, having had a gut-full of military exercises in the wet and cold, I try to avoid it now unless I have to. With no sign of the weather improving, I sacked it and went home to dry my kit and think of something else to do.
I ordered a Rockmite 20 transceiver kit a while back and it's been sat in a draw waiting for just such an occasion. The Rockmite is a QRP CW transceiver available through http://www.smallwonderlab.com. With the connector pack, I think I paid about £30 in all and the service was exceptionally good.
QRP is amateur radio-speak for very low power. I'm not sure what the exact definition is but I guess it's anything pushing out less than about 5 watts transmit power. A transceiver means it transmits and receives. CW means it's morse code only (ie, no voice comms). And the '20' means it works in the 20 meter band - the transmit frequency is 14060 kHz, which is the popular QRP frequency in that amateur band. There are Rockmite 40s and 80s too but I chose the '20' as it means it will have the smallest antenna. Why is that important?
Well, as well as wanting a nice little kit to build and a radio to practice my v slow, v poor morse on, I wanted something that was portable too so I could take it out with me and it would give me something to do in the evenings by the campfire, etc. So it had to be small, low power and with the smallest possible aerial. However, being in the HF bands, you can still get some good distance (across UK and overseas in good conditions). So, it's a compromise - HF band means bigger antenna but longer legs.
Anyway, the kit took me an afternoon to build, including my first ever surface mount device: woo-hoo! If you like building things, you'll know how satisfying it is. The instructions are very good but still leave you with a few decisions to make. The pictures below show the build in various phases. It's a small board and you need a steady hand!
Starting out
Helping hands
Lots of soldering
In the box
Testing
Ta-da!
The next day, I plugged in a dummy load (looks like an antenna to the radio but doesn't transmit any signal - we use them for testing when we don't actually want to send out a signal) and ran through the test procedure. Everything looked OK and I managed to resolve a problem with the morse keying circuit by fitting an extra switch. This is the beauty of amateur radio - you can modify and adapt things to get what you want. I checked the oscillator (generates the correct transmission frequency) was working by placing the unit near another radio tuned to the oscillator frequency - a nice stable tone shows that everything is good.
So that I could make it a portable unit, I added an internal connection to run it from a 9V battery and a switch to select the battery or an external 12V DC source.
The whole lot fits in a metal water-resistant box 13 x 8.5 x 2.5cm. some people put them in even smaller boxes - there are pics on the web. To be honest, the hardest thing was mounting all of the connectors and soldering the link wires in a confined space so I think a bigger box was better for me. The board was mounted on M3 bolts to hold it steady.
I'm pretty pleased with the way it has all turned out and it looks neat and tidy in the small box. I had to get a BNC-to-SO239 adaptor (the connector to the antenna) as all of my other kit uses those.
The antenna has two 5 meter 'arms' of 0.9mm copper wire, with a co-ax feed cable soldered in the middle. The plan is to use bamboo canes or trees to support the aerial when portable, using a nylon cord to suspend the feed and insulators. The feeder cable is coiled 6 times before it connects to the antenna arms to prevent stray signals (acts a bit like a 1:1 balun). At the moment, it's connected between the house and garage for testing but I'll post pics of the portable arrangement soon.
Whilst 2 x 5 meter arms still sounds quite large when thinking about antennae, it would be twice the size for a Rockmite 40 and twice as long again for the Rockmite 80, assuming you were using a 1/2 wave dipole antenna.
You can use other antenna configurations along with an antenna tuner but I wanted to minimise the amount of kit I had to carry so I chose a resonant antenna with a good match to the radio (measured at 1.3:1 at the moment). Furthermore, with only about 500 milliWatts of power output, I wanted to make maximum use of the available power. I may play with other configs in the future (eg, 5/8 wave vertical on my fibreglass pole) but i'll stick with this one for now.
Anyway, on test, it all seems to work well through the antenna. The only thing holding me back at the moment is my really poor morse skills: I'm getting there! But, I could certainly hear other operators on the band, even with my antenna in a less than ideal location b the side of the house.
For those who use paddle keys instead of straight keys, you can adjust the dot speed using the mode button. The audio is via headphones and there is a volume control too. Pressing the mode switch briefly also reverses the transmit and receive frequencies (you need to have a small offset or you can't hear the other guy transmitting to you) so you sort of have two channels close together.
So, great little project and I look forward to getting it out there and trying to make some very slow contacts with a lot of morse mistakes! For anyone starting out in amateur radio who just doesn't want to chat on 2m VHF (which is ace by the way but short range), this is a great way of getting onto HF and a good reason to learn morse.
It's interesting as there seem to be a couple of different groups of bushcrafters: those who just go out for the sheer hell of it and those who use it as a means of getting to somewhere to indulge their other interests - eg, canoeists, photographers, radio guys, etc. A broad church indeed.
If you have no interest in mobile communications or amateur radio, stop now as this is going to bore the pants off you.
Well, I got rained out of the hills the other day - exceptionally wet, consistent downpours and increasing risk of hazardous solo stream-crossings turned me back after one night as I really wasn't enjoying it anymore. Frankly, having had a gut-full of military exercises in the wet and cold, I try to avoid it now unless I have to. With no sign of the weather improving, I sacked it and went home to dry my kit and think of something else to do.
I ordered a Rockmite 20 transceiver kit a while back and it's been sat in a draw waiting for just such an occasion. The Rockmite is a QRP CW transceiver available through http://www.smallwonderlab.com. With the connector pack, I think I paid about £30 in all and the service was exceptionally good.
QRP is amateur radio-speak for very low power. I'm not sure what the exact definition is but I guess it's anything pushing out less than about 5 watts transmit power. A transceiver means it transmits and receives. CW means it's morse code only (ie, no voice comms). And the '20' means it works in the 20 meter band - the transmit frequency is 14060 kHz, which is the popular QRP frequency in that amateur band. There are Rockmite 40s and 80s too but I chose the '20' as it means it will have the smallest antenna. Why is that important?
Well, as well as wanting a nice little kit to build and a radio to practice my v slow, v poor morse on, I wanted something that was portable too so I could take it out with me and it would give me something to do in the evenings by the campfire, etc. So it had to be small, low power and with the smallest possible aerial. However, being in the HF bands, you can still get some good distance (across UK and overseas in good conditions). So, it's a compromise - HF band means bigger antenna but longer legs.
Anyway, the kit took me an afternoon to build, including my first ever surface mount device: woo-hoo! If you like building things, you'll know how satisfying it is. The instructions are very good but still leave you with a few decisions to make. The pictures below show the build in various phases. It's a small board and you need a steady hand!
Starting out
Helping hands
Lots of soldering
In the box
Testing
Ta-da!
The next day, I plugged in a dummy load (looks like an antenna to the radio but doesn't transmit any signal - we use them for testing when we don't actually want to send out a signal) and ran through the test procedure. Everything looked OK and I managed to resolve a problem with the morse keying circuit by fitting an extra switch. This is the beauty of amateur radio - you can modify and adapt things to get what you want. I checked the oscillator (generates the correct transmission frequency) was working by placing the unit near another radio tuned to the oscillator frequency - a nice stable tone shows that everything is good.
So that I could make it a portable unit, I added an internal connection to run it from a 9V battery and a switch to select the battery or an external 12V DC source.
The whole lot fits in a metal water-resistant box 13 x 8.5 x 2.5cm. some people put them in even smaller boxes - there are pics on the web. To be honest, the hardest thing was mounting all of the connectors and soldering the link wires in a confined space so I think a bigger box was better for me. The board was mounted on M3 bolts to hold it steady.
I'm pretty pleased with the way it has all turned out and it looks neat and tidy in the small box. I had to get a BNC-to-SO239 adaptor (the connector to the antenna) as all of my other kit uses those.
The antenna has two 5 meter 'arms' of 0.9mm copper wire, with a co-ax feed cable soldered in the middle. The plan is to use bamboo canes or trees to support the aerial when portable, using a nylon cord to suspend the feed and insulators. The feeder cable is coiled 6 times before it connects to the antenna arms to prevent stray signals (acts a bit like a 1:1 balun). At the moment, it's connected between the house and garage for testing but I'll post pics of the portable arrangement soon.
Whilst 2 x 5 meter arms still sounds quite large when thinking about antennae, it would be twice the size for a Rockmite 40 and twice as long again for the Rockmite 80, assuming you were using a 1/2 wave dipole antenna.
You can use other antenna configurations along with an antenna tuner but I wanted to minimise the amount of kit I had to carry so I chose a resonant antenna with a good match to the radio (measured at 1.3:1 at the moment). Furthermore, with only about 500 milliWatts of power output, I wanted to make maximum use of the available power. I may play with other configs in the future (eg, 5/8 wave vertical on my fibreglass pole) but i'll stick with this one for now.
Anyway, on test, it all seems to work well through the antenna. The only thing holding me back at the moment is my really poor morse skills: I'm getting there! But, I could certainly hear other operators on the band, even with my antenna in a less than ideal location b the side of the house.
For those who use paddle keys instead of straight keys, you can adjust the dot speed using the mode button. The audio is via headphones and there is a volume control too. Pressing the mode switch briefly also reverses the transmit and receive frequencies (you need to have a small offset or you can't hear the other guy transmitting to you) so you sort of have two channels close together.
So, great little project and I look forward to getting it out there and trying to make some very slow contacts with a lot of morse mistakes! For anyone starting out in amateur radio who just doesn't want to chat on 2m VHF (which is ace by the way but short range), this is a great way of getting onto HF and a good reason to learn morse.
It's interesting as there seem to be a couple of different groups of bushcrafters: those who just go out for the sheer hell of it and those who use it as a means of getting to somewhere to indulge their other interests - eg, canoeists, photographers, radio guys, etc. A broad church indeed.
