Something Different For The Weekend

Road Trip! Yup rather than building, fixing, tinkering, how about a bit of heritage?

The work at Bletchley Park was a significant milestone in the proceedings of World War II and I’ve been meaning to go and have a look for a while, especially after the release of The Imitation Game the other year, which gave an injection of Hollywood flare into a topic which was shrouded in secrecy for all the right reasons. Added to that The RSGB National Radio Centre is on site. You may ask why they are co-located? Good question. During World War II the relevant Government Departments sought out the assistance of Amateur Radio enthusiasts around the country for the sole purpose of monitoring the enemy’s radio communications. These radio stations termed Y stations, armed with their Morse skills recorded coded transmissions, frequencies, times and other ancillary information which was passed back to Bletchley Park to allow the teams to attack the coded messages.

Anyway, go and have a look if you get chance. If nothing it will fry your head with the mind blowing genius of the individuals who accomplished phenomenal mathematical and engineering tasks.

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These are all from the main mansion house where they’ve preserved some of the sets and props from The Imitation Game. All the very clever stuff is dotted around the site in the famous Huts where there are displays and exhibitions, including a rebuilt Turing Bombe

The video above is the rebuilt/restored Turing Bombe running a decode cycle.


Print your own workshop tools

One of the reasons I never have any money is my good mate Mat, who has the natural ability to sniff out anything cool in the world of technology, make it do stuff it was never intended to do and convince you that your life isn’t complete until you own one too.

I can safely say the boy has outdone himself this time by getting one of these!


Yep a Makerbot clone, CTC 3D Printer costing an eyebrow raising £280 from eBay! That’s not much more than a decent quality normal printer I hear you say. Exactly!

I’ve been interested in these things since they first appeared and dismissed them as a complete waste of time unless you were an art student or involved in design/graphics/manufacturing. Not any more! Admittedly you’re buying at the cheap end of the market here but the CTC printers are all open source with a huge community and following out there providing designs to print along with hacks, mods and updates.

In short, all you do is load the design you want to print onto an SD card and plug it into the printer or hook a PC to it to upload the slice files, which contain the data the printer needs. Press print and off you go.

If you’re like this guy (please watch this because the guy is very talented and I wish I had that kind of artistic ability) you can design everything yourself using free software or you can hit the repository of all things printable at Thingiverse, pick what you want or feel you now need just because you can print it and off you go.

We’ll get the the how it does it in a moment, but back to the title of this instalment.

Ever since I’ve been playing with electronics and bits I’ve always wanted a more professional and posturally pleasing way of holding circuit boards that I’m working on, rather than being hunched over them like Quasimodo, firing bits and pieces off all over the floor as I try to solder them.

I wouldn’t mind a Panavise, but they’re stupid money for what you actually get and you have to buy all sorts of add-ons to make it workable to all situations that may arise.


Equally, I was considering one of these, but again at £70 is a lot of dosh for not a lot.


My solution so far has been this –


Don’t laugh, costing a grand total of nothing and made from some off cuts of wood laying around the garage it’s done me all right so far. It has it’s limitations in that the wood sticks when you try to release it’s arboreal grip on your PCB and you have to use masking tape to hold stuff in place as you wrestle to invert the board to solder, but it works.

So when Mat said “so what do you want to make?” the reply was “how about one of these?”


Thingiverse has the project files there all ready to go, so on a freezing cold weekend why sit in a subzero garage trying to assemble another Chinese QRP transceiver, when you can sit indoors watching a cool toy print you something useful?

If you envisage high quality plastic akin to injection moulded products printed in the blink of an eye, forget it.

This is a slow process and is very much a hands on affair with a sprinkling of trial and error thrown in for good measure.


The printer slowly builds your wanted item in layers (or slices) with an outer shell of a defined thickness containing a honeycomb cellular structure out of, in this case PLA which is fed in filament form into the print head which is at 200+ C , where it melts and is extruded out onto a heated glass platen. The number of shell layers and the size of the honeycomb interior can be varied and will influence the mechanical strength of the finished article. The more dense you make it, the longer it takes to print.

I think Mat was very much up for the challenge as all his playing so far was printing upgrades and mods for his printer (print your own printer – very chicken and egg!), light sabres and copy of Deckard’s LAPD 2019 Blaster from Blade Runner.

Here’s the CTC putting the final shell layers on one of the frame pieces of the PCB holder

So after almost 12 hours we were rewarded with a pile of component pieces


If you notice, some of the parts aren’t very smooth. This is down to the need to apply a layer of adhesive (Purple coloured Pritt stick, nothing fancy) to the glass platen prior to printing to give the extruded plastic something to hold onto otherwise it just smears and runs around uncontrolled. Where we tried to print several of the smaller pieces in one run to save time we obviously just missed applying the glue layer in some places. Nothing lost as this is all about function, not form.

A quick trip to Screwfix and B&Q secured the necessary metalwork to assemble the holder.


And there we go! Not bad for a first attempt. There were a few minor snaggings worth mentioning. The design encompasses captured nuts on the black PCB holder/jaws. Unfortunately when pushing the M4 sized nuts into the printed hexagonal shaped holes the pieces split because they were just a little too small for the job. Added to that the plastic construction is laminar and any force driven between those layers causes it to fracture.


The top item is the broken part and you can clearly see the thin outer shell containing the large honeycomb internal structure. After a bit of thinking we decided to double the shell layer thickness and decrease the honeycomb size by 50% and try again. The bottom part is a print we abandoned a few minutes in due to a rethink, which gives a good visual as to how 3D printing works. You can print with 100% density i.e. solid BUT it’s still a laminar construction not a single solid piece. That said the final jaws we printed are as solid as you like and do the job nicely. A gentle application of a craft knife blade shaved off sufficient plastic to allow the M4 nut to sit snugly in its allocated hollow.

Total project cost £12-62. Exactly! Plus this was so much more rewarding than just buying something. The bonus of all this is, when I put my soldering iron through it or knock it off the bench or it breaks, press PRINT and your spare part is there ready for you in the time it takes to make and drink a couple of cups of tea.

Here’s the best bit. If you don’t want to spend out on a printer of your own or need a single item printed in a special medium (you can print all sorts of resins and plastics) there’s a community network called 3D Hubs which is tied in with Thingiverse. Here, commercial and private owners offer the use of their printers to print whatever you want. Yes it costs you, but you’ve got access to all sorts of grades of printers depending on what you want to make. I was pleased to see that I’ve got 4-5 local 3D Hub members very close by, if you live in London you’re tripping over them at every street corner!


Free Technical Books

At the risk of triggering spam filters on a global scale, here’s a resource that may have mileage the world over.
I am still a big believer in tangible reading material rather than ebooks simply because there’s something nice about being able to leaf through paper pages. Why would you want to replace your book shelves or library with a Kindle? That said there are occasions when being to scour a single paragraph or chapter of a technical manual for that golden nugget pays dividends.

I stumbled across this site the other day and it’s a huge repository of scanned and digitised technical books on which the copyright has lapsed.

Admittedly some of these are very old, but like any library of reference material there’ll be something in there for someone somewhere.

Chinese QRP Transceivers #2 – Pixie v3

Well my eBay Pixie purchase eventually landed the other week. The delay in building it has been due to a slight absence of components in the kit which was annoying as my seller was the one rated by others on both eBay and YouTube. That said he no doubt just buys them in by the truck load wholesale so I’m not grinding an axe.

So armed with a few extra ceramic capacitors I decided it was time to fire up the soldering iron and see if this thing actually works.


You don’t get much for your £3-92 but with a little care and attention (it’s needed as this board is tiny and the positioning of the components is pretty tight in places) you get this.


Still armed with a suitable amount of scepticism I hooked things up for the necessary smoke test.


Here we’ve got everything ready to go on my desk. My capacitive touch key is plumbed into my K16 Keyer (still minus a case) which converts the ‘dit-dah-common’ wiring of the touch key to the ‘key-common’ input required by the Pixie as it’s geared for a straight key. The K16 also provides a sidetone so you can hear what you’re tapping out on the key. The Pixie is on a dummy load and my iPod speakers provide a powered audio output.

With my FT-857D set to 7.030MHz the battery was duly attached to the Pixie and . . . it worked.

(For the non radio crowd, the dummy load is a “fake antenna” which absorbs the generated radio signal to prevent it getting out into the real world just in case you’re accidentally producing anything nasty and illegal which would cause Ofcom to come a calling. The reason the FT-857D is receiving the signal without a real antenna on the Pixie is that both radios are about 6 inches away from each other and in a similar manner to placing an analogue quartz watch next to set of head phones and being able to hear a tick, you will pick up some localised radiation.)

You note the genuine surprise here as for £3-92 I really wan’t expecting much!

I even cranked up Fldigi and stuck it in CW mode to capture the moment.

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Here are my feeble attempts at a CQ call immortalised as a memento to this little transceivers inaugural outing!

The next step was to stick it on a real antenna. Unfortunately, as the waterfall in the screenshot above shows, the 40m band was very quiet at that time so there wasn’t an awful lot to hear, so I’ll give it another outing later when the band’s more active.

This Pixie is a V3 and I’m still waiting for the V4 to arrive via China Post.

I will add that I’ve pimped this Pixie by replacing the stock 7.023MHz crystal with a 7.030MHz. This will put it slap bang in the middle of the CW centre of activity in the 40m band.


Hamcrafters K16-BAT CW Keyer Kit

With a severe weather warning in place and promises of wind speeds of 80mph+ overnight, today has been spent fixing a run of fence panels which were about to go down like a stack of dominoes thanks to just one post which had worked its way loose in it’s socket. If it wasn’t my fence it would have been like the perfect physics lesson watching the ripple of reflected waves!

As a result the planned day of “doing lots of stuff” failed and resulted in “a small amount of stuff” being concluded, which isn’t bad as I can easily become distracted and never bring things to a conclusion.

The LCD shield for the Arduino was completed pre fence panel removal and this little project was concluded post hammering in yet another piece of angle iron to support my fence.

When I was researching the Pixie transceiver I commented on the K16-BAT and have been sat for several weeks waiting for it to land. Ironically the Americans get to have all the fun stuff readily available as outside of the US of A there are very few people who supply kits as agents/retailers or an adaptation of the original idea.

As such you end up paying for postage, waiting a lifetime and then get mugged by the Post Office who enhance the mugging by Border Force for the 30p customs import charge. I’m so glad the borders of this great country as safe from rogue postage!

Political rant over, you don’t get much for your money with the K16-BAT


But building stuff is fun, so you can turn the above into the below in 30 minutes


The finished article is tiny and is begging for a tiny enclosure to keep it safe and warm.

As a foot note I’ve had to reverse the L & R inputs when using my capacitive touch key to get it working properly, which is odd and I need to look at again. That said it works a treat with the homebrew paddle thanks to the minor modification and as a stop gap until I save my hard earned (or I win a small amount on the Lottery!) for a Kent TP1-B it’ll do the trick.

Today’s job was to lash up a switch and speed control panel so that I could reduce the speed of the output simply because in its default setting the K16 sounded more like an M16 on overdrive!

I’m awaiting some push to make buttons and a 10k panel mount pot to make a nice panel for an enclosure, but in the meantime I made use of some PCB mount bits and bobs to get things going.


With a gentle tweak of the speed pot (blue thing on the far right) everything was calmed down significantly!

Here’s a little video of things in action

Addendum 13/02/16

I’ve resolved the incorrect paddle assignment with the K16! Unfortunately, for something so tiny this thing comes with a manual of 32+ pages which covers everything in every possible application and makes finding a simple answer not that straight forward.

By default, for some bizarre reason the left and right paddles are swapped by the K16 requiring you to delve into the menu system to amend this. Also it’s not a top level menu function and requires you to access option X from the Immediate Command List, followed by option X again in the Extended Command List, Extended Command List X option being Exchange Dit/Dah inputs (swap).

The added snag is that with the paddles mapped arse about face you’re then trying to tap out characters in Morse on an iambic paddle the other way around . Not sure who thought that one up!

I’ll rewire the K16 when I fit it into an enclosure but I’m currently waiting on a very slow boat from China to deliver some push buttons and a panel mount rotary pot. Unfortunately if you want to do these things akin to the budgie, i.e. cheep (I know!) the pay back is delivery times that make a snail look like a Formula 1 car. Added to that it’s currently Chinese New Year which will add to the delays


Chinese QRP Transceivers #1

I’ve been sat twiddling my thumbs waiting for my Pixie transceiver kit to arrive so that I could crack on with my computer CW project, which has allowed me to hit the forums and have a general scout around as to how best to utilise it or even pimp these things for other applications.

By absolute coincidence the guys at FPARC posted an idea on the club forum yesterday suggesting that the Pixie kit would be an ideal club project for those new to construction or looking to complete Intermediate Licence builds. There was also the suggestion of a workshop tent at the forthcoming field days and then the idea of a Pixie net and test transmissions across the parade ground at the fort. Brilliant!

Like everything once a pool of like minds get together the ideas start flowing including the brilliant suggestion of using a piece of free DSP filtering software on a Netbook to give a much clearer reception of a single signal as the front end on a Pixie is “as wide as a barn door”. Again an excellent idea.

One suggestion I stumbled on in kb2hsh’s blogspot was the idea of using a K1EL K16 keyer kit between the Pixie and the Morse key to allow a paddle or Capacitive Touch Key to be used with it as, in its native form the Pixie will only work with a straight key.


Ironically this diminutive device replicates nearly all the features of the Winkeyer which I commented on in my first post about computer generated CW.

Although I’m not planning to use it for all of the features at the outset it’s useful to have around as a potential “evolving” project. Again its another waiting game while the USPS delivers!

Now as much as I’d love to splash the cash and by a really nice Morse key to join my growing pile of kit, I am actually starting to get the hang of my touch key and the action is making sense. Ironically the CW Geeks Guide to choosing a Morse key makes comment about how it takes real practice to make dits and dahs that are the same length over and over and reports of arm ache after about 30-40 mins use with a straight key. Added to that I built my Capacitive Touch Key and it’s a waste not to use it.

There are loads of good sites out there discussing everything to do with Pixie Transcievers, and a select few are here for reference

I also stumbled across literature relating to one of the iconic homebrew QRP transceivers, the Forty-Niner


Once again there are a host of Chinese clones available as above but at the minute I’ll stick to my Pixie and Frog builds as, at the end of the day they all do pretty much the same thing.

The Foxx range of kits are still popular and companies such as Kanga still supply them.





Arduino Morse Decoder #2 – LCD Shield build

Some people may ask why bother posting something as simple as this, but for the uninitiated it shows how simple this stuff can be and may spark some enthusiasm.

After having sat around for a few weeks waiting for a stray component or two to land I’ve eventually built the LCD Shield portion of this project. This will be the output display for the decoder and is pretty crucial to proceedings.

As this stage is purely development I decided to build the shield so that I could plug various LCD modules into it to try different sizes and colours etc. before hard soldering my chosen one onto a board.

With that in mind I substituted a header system to give plug and play options.


The only snag with this is that the LCD is too heavy to self support purely on the headers alone and starts to sag quite alarmingly without some form of support!


A 12mm M3 screw turned upside down with a nut located a few millimeters along the thread does the job quite nicely until I can find something a little more permanent.


Aesthetically, once docked to the Arduino board this starts to look like a bad game of Jenga but this is purely prototyping!


And as proof that everything works nicely here’s the Morse Decoder display 176 seconds into its existence next to the one I put together from my existing shields on 24th January. 1202472 equates to 13.9175 days! For some stupid reason I haven’t got the heart to unplug it.

Here’s the big brother screen (20 x 4) to the 16 x 2


This has a much nicer feel to it, probably because it’s less cramped and I’m glad I didn’t flog it on eBay as I’d been planning to do. Just goes to show that disposophobia can be a good thing!

It is seriously heavy compared to the 16×2 screen and is currently perched on a 12mm piece of plastic pipe which I hacksawed off and placed between the back of the screen and the shield PCB otherwise it would have collapsed taking the pin header with it!