simonr Posted February 10, 2013 Author Share Posted February 10, 2013 Undoubtedly there are some geeky people on the air - I'm probably one of them! But as has been said there are some really interesting ones too. Its surprising to me that even in this age where you can talk to someone in Australia via email, phone or a forum effortlessly from the UK, there is an enormous thrill talking to someone even a couple of hundred miles away with a cheap radio & a length of wire slung between the house & shed! The difference is, you have achieved it yourself, not thanks to the endeavours of corporations with billion pound budgets. More importantly, when the mobile networks and Internet go down - radio still works and nobody charges you for using it! This is the reason it's a part of the emergency planning for disasters and why groups like 4x4 Response have encouraged members to get novice licences. The Novice licence is fairly straightforward with a few hours studying or tuition. It almost seems crazy not to do it! Intermediate and full licences are a bit more involved but it's amazing how many people get hooked and go on to get a higher class licence. There are lots of very low cost transceivers on eBay as well as old military kit. My feeling is that HF (anything below 50 MHz) is the most fun because of the distances you can cover. I can easily talk to stations over most of Europe and the UK and occasionally when the atmospheric conditions are good, the US & Canada. Although 10w into the antenna seems limited, there is nothing stopping you building a high gain antenna that focuses the radio waves into a tight beam - and allows them to travel much further. It's like changing the focus on a Mag Light. Low gain will allow you to make contacts locally in any direction. High gain will allow contacts in a narrow beam much further away. The beauty of it is they are all just made out of bits of wire! Nothing special, no magic, nothing you can't make your self! Give it a go! Si Quote Link to comment Share on other sites More sharing options...
western Posted February 10, 2013 Share Posted February 10, 2013 A few weeks ago, I had a great chat with a guy i Honolulu Hawaii through my local 2m repeater, I believe he was using a echolink gateway. not bad from a cornwall based indoor aerial. Quote Link to comment Share on other sites More sharing options...
simonr Posted February 10, 2013 Author Share Posted February 10, 2013 I'm sitting on 7.118mHz at the moment. 7.115 was busy. Si Quote Link to comment Share on other sites More sharing options...
01gue5t Posted February 10, 2013 Share Posted February 10, 2013 new frequency needed as all listed occupied lol Quote Link to comment Share on other sites More sharing options...
zoltan Posted February 10, 2013 Share Posted February 10, 2013 I'm getting interested, how much wire do you need to put up to make it worthwhile? I see a lot of Clansman radios on Withams, are these in anyway suitable or are they locked to military frequencies? I like the idea of radio in my Gaz Quote Link to comment Share on other sites More sharing options...
simonr Posted February 10, 2013 Author Share Posted February 10, 2013 It depends on the band. For HF, the minimum is about a 1m diameter loop of copper tube up to an 80m length of wire (and anything inbetween). For VHF, the length is more critical to the frequency but say for 2m (145mHz), between 50cm and a meter is all you need! There is literally a good antenna for every band regardless of how much space you have. For HF, Magnetic Loops give the best performance per unit volume IMHO. Si Quote Link to comment Share on other sites More sharing options...
TSD Posted February 10, 2013 Share Posted February 10, 2013 Mag loops offer fantastic performance for the size, but the narrow bandwidth makes them a bit of a pain for those more used to 'pushbutton' operation, and there aren't so many commercial offerings because it's harder and more expensive to make them suitable for high power operation. Tuning can mostly be dealt with with a stepper motor and a microcontroller though. I was (and am) listening on 7115/7118 etc but didn't hear anything intelligible... I need more than an indoor 4ft whip antenna I have a 33" mag loop in bits in the garage - I know it's 33" cos I originally formed it around the BFG on the back door Quote Link to comment Share on other sites More sharing options...
simonr Posted February 10, 2013 Author Share Posted February 10, 2013 I have actually been thinking about the X-Loop! I fancy one that I can take on holiday - but even a 33" loop of copper pipe is going to get mangled going through airport baggage handling. My main thought is making it out of tinned copper braiding around a piece of lay-flat tube which you inflate to form a loop. Instead of a traditional variable capacitor, cut a piece of copper tube down the middle and glue them to either side of the central support spar with one each end of the loop soldered to one half. Sleeve it in PTFE and then slide another copper tube over the PTFE. The overlap provides the variable capacitance. If the outer tube were threaded, you could wind it up & down to tune. The coupling loop can just be a bit of coax. The whole thing would pack down into a rod, perhaps 75cm long. Just a thought. Si Quote Link to comment Share on other sites More sharing options...
western Posted February 10, 2013 Share Posted February 10, 2013 I'm getting interested, how much wire do you need to put up to make it worthwhile? I see a lot of Clansman radios on Withams, are these in anyway suitable or are they locked to military frequencies? I like the idea of radio in my Gaz Foundation licence holders can only use commercially available equipment refer to http://licensing.ofcom.org.uk/binaries/spectrum/amateur-radio/guidance-for-licensees/samplelicence07.pdf para 7 Equipment sub para 7[2] the current 2013 band plans are here http://www.rsgb.org/committees/spectrumforum/band-plans.php Quote Link to comment Share on other sites More sharing options...
simonr Posted February 10, 2013 Author Share Posted February 10, 2013 For the sort of money you'd have to spend on a Clansman radio, you can buy a much better general HF Transceiver IMHO. There are also software radios which just use the audio port on your computer! Si Quote Link to comment Share on other sites More sharing options...
Part1cle Posted February 10, 2013 Share Posted February 10, 2013 Used a length of wire fence, an ATU and an earth spike to get out on 80m in Shetland many years ago... Just to see if it worked, and it did. Those we spoke with were sceptical, to say the least. Quote Link to comment Share on other sites More sharing options...
01gue5t Posted February 10, 2013 Share Posted February 10, 2013 i did go on all frequency listed and found 3 uk nets in progress all at 5 n 9 GW7ORB Quote Link to comment Share on other sites More sharing options...
simonr Posted February 10, 2013 Author Share Posted February 10, 2013 How about we try again in 2 weeks (next week is the Donington 4x4 Show) which will give a bit of time to make antennas etc. Today, for me anyway, the problem was the number of contest stations in Europe running high power and bleeding across the band trying to get out to the US. Might be a bit quieter in a couple of weeks! Free offer! I have an old Trio TS-700 All Mode 2m transceiver in my loft which is designed as a base station but will run on 12v and I have used it mobile in the past. It's quite chunky (maybe 30 x 12 x 30 cm). If there are any Novice licence holders who would appreciate a decent Transceiver - you can have it for the cost of the shipping (or free if you collect). It puts out 25w IIRC so to be legal you couldn't use it on max power. It has an old fashioned vernier tuning dial (not in the slightest bit digital) but it is still very good. SSB on 2m gives the possibility of getting out way further than on FM. Si Quote Link to comment Share on other sites More sharing options...
zoltan Posted February 11, 2013 Share Posted February 11, 2013 I'd like this but I haven't even started down the road to a license yet Quote Link to comment Share on other sites More sharing options...
cactus Posted February 16, 2013 Share Posted February 16, 2013 Simon, I have been using 2 and 70 in the L/R for over 30yrs and find it very useful! I have a HF Transceiver but...No aerials.... How about a X-Eng HF Ant.? I'm sure they would sell well! All the HF Mobile aerials I've seen are too fragile for "our" use. Quote Link to comment Share on other sites More sharing options...
ChrisB Posted February 16, 2013 Share Posted February 16, 2013 I've been experimenting with my SGC-237 autotuner and a long fibreglass pole with a bit of wire taped to the side. Pole bolted to the spare wheel carrier of my disco (without the wheel!). Tuner mounted inside the carrier. Reasonable success. but definitely needs a permanent solution. Next move is to try a piece of ali bolted to a roofrack crossbar with the ATU underneath. Pole bolted to crossbar. Theory says this should be much better! Earthing by braid to existing antenna mount on roof. The ATU will load up anything, ideally 9ft long, but I have used it on higher bands with 6ft. Problem is, importing a 9ft whip from the US is expensive, unless you buy bulk, or a two-piece which I think is too stiff for our use. Looking forward to the X-Ant! Chris Quote Link to comment Share on other sites More sharing options...
gadget Posted February 17, 2013 Share Posted February 17, 2013 I've been experimenting with my SGC-237 autotuner and a long fibreglass pole with a bit of wire taped to the side. Pole bolted to the spare wheel carrier of my disco (without the wheel!). Tuner mounted inside the carrier. I've had reasonable success with an SGC-231 mounted on the bulkhead feeding a 16ft fibreglass antenna mounted on the bumper fed via coax. The antenna was made from a disused Antron A99 with the loading section removed. I've not played radio for a while... Quote Link to comment Share on other sites More sharing options...
G4FUJ Posted February 19, 2013 Share Posted February 19, 2013 Well, well. I miss the forum for a couple of weeks and lots of things happen! Simon, the TS-700G (slightly later model) was only 10W from memory, so I guess the 700 is probably the same. Have 160m - 70cm in the 90. Will have similar in everyday car (when I replace the MINI - still Hippo hunting, or maybe a Jimny). 80m - 23cm at home (but 80m suffers with horrendous QRM). So for inter-G (intra-G? ) 40m (or 60m) is best for me. Radio, like Land Rovers, is in my bones - licensed since '77 and a marine Radio Officer for some 15 years... Cheers, Fudge Quote Link to comment Share on other sites More sharing options...
01gue5t Posted February 24, 2013 Share Posted February 24, 2013 Did it happen today? Quote Link to comment Share on other sites More sharing options...
G4FUJ Posted February 25, 2013 Share Posted February 25, 2013 Dunno. Forgot all about it - :swmbo: decided she wanted to go out... Quote Link to comment Share on other sites More sharing options...
simonr Posted February 25, 2013 Author Share Posted February 25, 2013 For mobile use, I've found that an ordinary (long) CB antenna with an LDG Auto Tuner gives reasonable results from 3.5Mhz to 50Mhz At 3.5Mhz the tuner can bring it down to about 1.8:1 SWR, 1.5:1 on 7Mhz and 1:1 on 28Mhz which could be worse! Though it's not strictly legal, I have the first 40 memories on my IC-706 set to the UK CB Channels - and thus can use it on trips & play days to talk to everybody else. Of course, I limit the power to 4W or so This weekend I couldn't listen because I needed to fabricate & weld a new lower shock mount on to my Axle - and needed it done by lunch time! Next week though! I've started a little experiment to build a semi portable magnetic loop antenna for 80/40/20m. eBay has just given me this as the tuning capacitor and this to make the loop itself out of, using this spreadsheet to calculate the values etc. Because of the skin effect (where at radio frequency, the current only flows though the outer skin of a conductor, 0.6mm deep at 3.5Mhz), loops work best with big diameter copper tube. However, bending anything more than 15mm tube into a loop is near impossible - and not very portable. I figured that a strip will behave just like a flattened tube but is very easy to form into a loop. My plan is to bend the ends of the strip at 90 deg and bolt these directly to the Tuning Capacitor then use an RC Servo to rotate the capacitor adjustment. I need to find a telescopic plastic rod for the vertical support spar. Then to collapse, you unbolt one end of the loop and roll it up more tightly around the Capacitor, collapse the telescopic rod and use this in it's short form to hold the loop tightly wound. A 5' diameter loop should compress to a 1' diameter making it practical to transport. The feed in is just going to be a 6" diameter inductive loop to excite the main loop. Loops have a reputation for being very noise immune as well as directional - so I'm hoping to be able to get out a bit further and cut through the plasma TV interference!Last night, I spoke to a chap in Connecticut on 80m using a 14m vertical bit of wire - it's the furthest I've got so far with limited power and an omnidirectional antenna. I hope the loop will improve things! Si Quote Link to comment Share on other sites More sharing options...
GW8IZR Posted February 25, 2013 Share Posted February 25, 2013 A piece of ldf5-50 is very light and makes a useful loop. Regards Paul LA/GW8IZR Quote Link to comment Share on other sites More sharing options...
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