Portable Hexbeam v’s Cobwebb

After a few more weeks of not getting on the air I managed to man handle the portable Hexbeam up to about 4 above ground level (Note: must get that tilt base sorted out) to compare it against the Cobwebb I have in the loft.

So before we go down the ‘It’s not scientific’ route. I’m ok with that, no big deal its just a bit of fun.

There are some significant differences between the two antennas that I hadn’t fully appreciated. Firstly the noise levels on the Cobwebb were quite a bit higher, which seemed to make the Hexbeam sound quiet, when in actual fact there was no significant difference on the higher bands when it comes to S points. But, the lower noise levels made it much nicer to use. The image below shows what I mean. There is a band of ‘mush’ slap bang in the middle where I switched onto the Cobwebb. Just so you know, the Cobwebb was way quieter than the vertical I had before.

cuSDR Hexbeam vs Cobwebb

It’s not a huge visual difference on the screen but the ears make it obvious. The gain on the Hexbeam made it easy to make contacts with C06LA answering on the first call, I’d never expect that on the Cobwebb.

You can also see that the signal strength is fairly similar, that was W4UH calling CQ.

So not much in it when the Hexbeam is really low, I’m sure it’ll beat the pants off the Cobwebb at 12m but interesting to see that the Cobwebb is ‘noisier’. Especially as I thought it was quite a quiet antenna.

Portable Hexbeam

Saturday saw me opening a beer celebrating finishing off the new decking area…which means….Sunday saw me finishing off my portable hexbeam from Folding Antennas. The build took quite a while, about 8 for the hardware and about 3 for the layout and tuning. I’ve not used it much in anger as the rains started coming.

An early doors write up is here…..but so far its looking worth the build time. Here’s a shot of the half finished decking…oh and a half finished antenna.

2014-03-25 12.10.50

QRSS v3 kit

Before the decking project was formally sanctioned and actioned through the domestic funding board / xyl I had thought about ordering a little kit to build over the summer. I had built the v2 QRSS kit from Hans Summers, G0UPL and have used it on the 30m band and frankly enjoyed both the built and the fun tinkering with it.

The v3 kit changes the design slightly in as much as it used a more common 16×2 LCD and the PCB size as increased slightly. But from what I can tell there is a deal of difference between the two designs. Both encourage the builder to tinker with the PA’s, increase functionality with GPS and use the add on LPF relay to build a multi band TX. The one big and obvious change is the used of the dedicated DDS.

Plans for this kit are to still do the build and then buy up 10 kits and build them at the BEC fab lab one Saturday. I will no doubt get a suitable date for the build day at next weeks club meeting. Until then its finish the decking or be in trouble with the domestic CEO.

More new toys

For as long as I first heard about SDR i wanted to get involved. Unfortunately children and jobs got in the way of significant investment. Until now that is. I received an email from a local ham who had an Angelia board that he no longer wanted.

‘Did I want to buy it off him?’

‘Yes’ said I before even mentioning it to the domestic CFO / xyl.

Long discussion ensued and eventually I have come away with this….

IMAG0276

Needless to say some of the domestic staff were not amused. As a consequence I have an FT817 and a VX8-GE for sale. Any takers?

BEC Fab Lab

Not strictly Ham Radio but worthy of a mention, I dropped into the BEC Fab Lab today to talk to them about laser cutting some cases for our clubs summer build. We’ll be doing something simple this year ( the Hans Summers, GoUPL Ultimate QRSS kit v3 – mine is on order) and I’m keen to tie in what we do with them as we could use their services and they could potentially open up amateur radio to a wider audience.

I was really impressed and can’t wait to get my hands on their 3d printer, I just don’t know what I ought to print…perhaps a callsign badge

BEC Fab Lab

Rumours of my demise…….

Are of course untrue ;-)

Quite a bit has happened over the last few weeks. Primarily domestic and work duties have kept me away from the rig other than the occasional VHF contest appearance.

At home I have spent a considerable amount of time replacing cables and renewing bits and pieces that have succumbed to the Cumbrian winters and salt spray. The salty, windy air has corroded connectors, got into the coax outer (my poor connectors to blame) and generally caused some ‘issues’

So cabling all done

New telescopic mast purchased

New antenna purchased

So to the purchases. I bought a simple, manual 12.5m mast from Spiderbeam that is pretty substantial. Why no fixed mast? because radio is a hobby that I do and not the rest of the family and we enjoy the sea view more on that in another post. The antenna is a lightweight hexbeam from folding antennas. Again more info on that in a more detailed post. But suffice to say its all going down the same path. Simple radio. Nothing complicated. Nothing that can’t be easily moved or changed and no chasing the next rig / antenna / thing. Just turn on what I have and enjoy the simplicity.

Hold on a minute. I haven’t done the remainder of the decking….well at least I got to think about radio

Not much more to go now

Change is a really handy tool. I’m in the business of delivering projects which always means change. So when it came to managing some change at home I thought I knew what I was doing. When I say change I mean a little bit of landscaping that a fellow ham was going to do and at the same time put in a new cables and a post ready for my new mast and antenna. This mean a bit of planning, cost control and some stakeholder management. Or so I thought.

I had originally decided on extending the house and had some lovely plans drawn up (which included a mast and antenna), put them through planning (domestic / xyl and local council) had them approved only to find that the local builders wanted huge sums for a small job. Hence the scope was reduced to meet the budget.

For the last few weeks I have toiled int he freezing rain to drill new holes in the side of the house, removed old and corroded (poor finishing by me) cables and then set about running new ones before removing some old decking that was the cause of our problem (wooden decking and West Cumbria should be avoided). What is going to go in its place is a mast stub in the ground, ground mounted rotator, heavy duty 12.5m mast and a folding hexbeam.

The schedule is hectic but I imagine in a matter of 4 weeks I will be back on the air on hf and there will be a very tired out g7kse, ready for for some leisurely operating on hf and perhaps in time for some early Es. Until then its the UKAC VHF tuesday nights for me still.

SketchUp project cases

After completing a kit or small project I have a terrible habit of not finding a suitable box to put the thing in. This is partly due to the really unappealing array of cases on offer. Sverre, LA3ZA recently posted something regarding the ultimate qrss kit v3 that I gave a quick response to and this is supposed to be the long winded response.

Sometimes these cases are blow moulded polypropylene or extruded aluminium that needs better tools than I possess to make holes, especially square ones for things like USB connectors and LCD’s. So what’s the answer? well I prefer to use simple acrylic cases like those made by Dangerous Prototypes in a range called Sick of Beige (or SoB). these are simple flat sheets of acrylic that are laser cut and have 4 holes for fasteners. A really nice idea but its only half way there.

Generic-SoB-case

This company also like to encourage you to complete a project that looks nice. Not just with the case but also the PCB. They offer a few tools to help you do this. There are a few routes to take and I have found that with a bit of extra time you can make a really well finished project.

 1. PCB sizes

CADSoft Eagle is a piece of software that allows you to draw out schematics and then layout a PCB. There are loads of alternatives (Fritzing, KiCAD, DIP Trace etc.) but in order to make use of the tools. Eagle is the way to go.

DP offer a library of PCB sizes that fit their cases. Easy, just use one that fits the project you are doing. Just install the library and pick the right size of case. Take a look here for some more info. You’ll find links to the libraries there too.

2. Case design

Now it gets a bit more complex, but not too hard. You’ll need to look at some mechanical design tools. In simple terms we need to draw something that a laser cutter can cut out. In general the ones I’ve come across use .svg or scale vector graphics files to do the cutting. Not everything produces these files in an easy way. There are loads ways to do this, it just depends on your preference. I prefer to use SketchUp as it has a handy feature I’ll come onto in a moment.

The simplest way to modify one of these cases is to use the guide by Dangerous Protoypes themselves. This is available here

I’m not going to explain how to use SketchUp, there are loads of really good tutorials about and you can build up your skills using those. I tend to go for YouTube ones as they give you the basics you need quickly and easily, without too much jargon.

I’d suggest picking a standard size case first off and then using the other tools when you get the hang of things. Use tools like offset in SketchUp to get things lines and don’t forget about tolerancing to make sure there is a clearance where you need it. It sounds simple and it really is, just put the extra holes in where you need them and hey presto, nearly done.

Export to SVG using the tool and check with something like Inkscape to make sure your case looks right.

3. Case manufacture

As I said earlier, many of the machines I’ve come across just need the data. Seeedstudio is one manufacturer but there are plenty of others. Follow their instructions and upload your files. Pay the man (or woman) and you’ll get your sheets of laser cut material back in no time. You’ll need to get fasteners and your favourite supplier may be able to help. I have a really good industrial supplier a couple of miles down the road who gets excellent quality fasteners, otherwise Farnell, Rapid or RS will give you options. Failing that try eBay if you must.

4. Going a bit further

There is an Eagle Plugin that will give you the chance to export your (empty) board to SketchUp and almost certainly you will find the parts or near equivalents in the 3D warehouse to place on the board. Just remember that whilst SketchUp is good, you need solids to be able to line up properly and whilst a free (or £500 pro version) CAD package is going to give you most of what you need. It isn’t AutoCAD Inventor or Solidworks (at almost 10 times the price). I would suggest getting a handle on the software first before getting too embedded as you may find it frustrating if you can align holes for example.

If you do go for it then you can create some really good looking CAD drawing that can be rendered into photo realistic parts. Here’s one from the website.

model5

The range of free tools available to the hobby user is now amazing and no doubt will only get better over time.

This weeks learning

So far this week I have learnt that aligning parts in Google Sketchup isn’t as easy as it is in something like Solidworks. Still for a freebie programme I’m not going to complain.

Progress on the rotator project is slow, mainly because of the usual lack of time. But at least the idea is cemented in my head and now its just a case of doing the mechanical design and then hooking everything up. Below is a rough draft of the proposed Az / El arrangement for the clankies amongst us. I’ll complete the design either myself in a huge amount of hours or, more likely ask one of the CAD jockeys at work to fix it in a matter of seconds.

Rotator

With this arrangement it should not be complex to either fabricate, buy or 3D print parts to suit. The latter is a preference as then the model can then be used by anyone to get parts made either as laser cut solids or 3D prints.

The main parts will be 2 off nema 17 steppers, gears from actobotics (This may need to be adjusted to slow the steppers down sufficiently) and that nice radio artisan / K3NG chaps code with Anthony, M0UPU’s board.

Onwards and upwards

Arduino Rotator

The little project I have to homebrew an Azimuth and Elevation rotator has moved on a little. After spending countless hours researching the project I came across a couple of really useful resources. Firstly the Radio Artisan website has simply done the hard stuff with the codes and secondly Anthony Stirk, M0UPU has made a shield / board for easy interfacing.

I’ve ordered a board and will see what I can do with it once it arrives. Next weekend is SOS Radio Week so I’ll be hamming it up at St Bees Lifeboat station so I doubt I’ll get a chance to do anything but we’ll see.