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Making Waves – Building the KANGA Products OXO Transmitter Kit (Part 2)

December 21, 2019 Leave a comment

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Following on from yesterday when I started building this excellent kit from Kanga Products, I have today managed to build the rest of it, all that it needs now is a power source and a Low Pass Filter before it can be plugged into an antenna.  Neither of these are included of course but the power supply can be a simple 9V battery (or 12V PSU) and the LPF a simple 5 or 7 pole LC filter.

7The completed board

Overall the PCB was easily populated with the components and personally I shall add a polyvaricon to the terminal beside the XTAL labelled Cvar.  The option was to either bridge this and have the frequency rock set to the XTAL value or add a variable capacitor to enable a swing on the frequency.  Therefore I am going for the latter option.  If I have any criticism of the kit it is that the XTAL(s) supplied are in a large can – I would probably replace them with the smaller low profile ones – and they are supplied at 14.050 and 7.028MHz, not the QRP frequencies of 7.030 and 14.060MHz.  I am planning on designing/building a switched XTAL bank to allow operation on all the QRP frequencies from 80m – 20m (possibly 15m) using XTALs I have here.

 

I have yet to do a smoke test and check the stability of the RF generated yet but this will be in the next stage as I have other things to be doing now.  I shall be checking both with and without a LPF straight into a dummy load before I plug it into an antenna of any sort though.  I also need to find a suitable enclosure for it.

Making Waves – Building the KANGA Products OXO Transmitter Kit (Part 1)

December 20, 2019 Leave a comment

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As it’s nearing Christmas 2019, I decided to treat myself to an OXO TX kit from Kanga Products UK.  This is an updated version of the OXO transceiver made famous by the late GM3OXX now providing a multi-band version.  So I ordered it from KANGA and it turned up here yesterday in a jiffy bag/envelope.  Taking it out it was nicely packaged in a sealed plastic sleeve.

1

Making sure I had all necessary test equipment ready (including the Sandford Wattmeter also from Kanga Products) I set to work to start assembling it on the CVO towers workbench.

Opening up the outer sleeve and removing the contents I was pleased to see that all the components were sorted in separate bags of resistors, capacitors, transistors, etc.  tis makes individual components much easier to find as opposed to just having everything dumped into a single bag.

3 everything sorted into individual bags

The instructions needed to be downloaded from the website and consisted of a three page .PDF file.  To quote one paragraph from them:

“Though the fitting of the parts is straight forward, it is highly recommended that all components are soldered in the order they are listed in the component list”

Although this may seem a no brainer it is good advice as you can then mark off each component as it is fitted and it runs in order of resistors, capacitors, transistors, crystals and then connectors.  This also follows the order of the bags.  My only criticism here is that the coil isn’t mentioned in the list but is mentioned in a separate paragraph.  It needs winding by hand and is 17 turns of 24SWG ECW wound on a very small ferrite toroidal core.  This is surface mount and laid flat on the PCB and should be mounted first ideally.

4The PCB is nicely printed and fairly easy to follow

5

So, contrary to my earlier advice I first fitted the resistors to the board.  Fairly easy through hole devices and Dennis, from Kanga UK, has kindly listed the colour coding of each resistor beside its value in the list.  Not really necessary for those of us in the know but for those not familiar with resistor colour codes a handy help.

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Next I wound the coil.  The former is very small and this can be fiddly.  Note, if you are going to build one yourself do leave the ends long as if you cut them too short….  Anyway once wound I fitted the coil to the board using the plastic screw, washer and nut supplied before soldering the tails to the pads on the board.  Contrary to popular belief the enamel coating on the copper wire doesn’t melt away to reveal bare copper when you apply a soldering iron.  I use a Dremel Multi-tool to remove some of the enamel coating before applying solder.  Once this was secure I then applied the capacitors in order, with the large electrolytic one being fitted last of all, ensuring the polarity was correct.  that was it for today as work got in the way but I will continue when I next get round and will hopefully have it complete and ready to test next time.

Making Waves, New Opportunities, KW and beyond…..

September 28, 2019 Leave a comment

It has been a while since I have written anything on my blog but this is mainly because I have been rather busy.  The antenna business ( www.m0cvoantennas.com ) went from being busy to very busy at the beginning of the year and has remained so since.  In March of this year I was given the opportunity to take over as Director of K.W.Electronics Limited (Company #08587607).  progress was slow at first but in July 2019 I received certificates transferring over the title of Director to myself.

KW_Logo

KW Electronics was first founded in the 1950s by G8KW.  They produced many receivers, transmitters and accessories for the amateur radio market, the most famous being the KW Vanguard Transmitter that featured in Dr. No, the 1962 James Bond film as can be seen HERE.
Now under new ownership, KW Electronics Limited is all set to bring you new products aimed at the amateur radio and commercial radio market suitable for the 21st Century.
The first products introduced to the new KW Electronics company profile are a Morse Code Practice Oscillator, either completed and boxed or the same in kit form (not including the box.
DSC00716
The K.W.Electronics Morse Code Practice Oscillator available HERE
DSC00727
The K.W.Electronics Morse Code Practice Oscillator Kit available HERE
There are other things currently being worked on such as a VHF preamp and an all band active antenna (both for RX only).  We also currently have an all band HF antenna – the KW-V – which is the CHAD (Compact Helical Asymmetric Dipole) developed by Ken Ginn, G8NDL.  However, as we are awaiting some parts this is not currently available.
Full details of K.W.Electronics Limited can be found HERE.

Making Waves VHF and up….

Upon moving to the new QTH in February this year (2018), I decided that I was going to spend more time operating on VHF, UHF and above.  Sure enough, I got my trusty FT-480R set up on the bench and fitted the 2m 10element Yagi to the wall at the end of the house with a short Yagi for 70cm above it (and rotator below).  The added bonus of being 154m ASL was also something I planned to take advantage of.

 

I also had my FT-817 connected for UHF (70cm) and a transverter for 23cm.

c1zrqflxeaaoreu Transverter 

For 145MHz FM I bought a new FTM-320D (Yaesu) which I plugged into my Diamond X-50 colinear.

20180719_143018

Meanwhile, I had been monitoring the local repeaters on my handheld radios – Alinco DJ-G7 and Yaesu FT-252 from inside the shack, so I knew my coverage was much better than at the previous QTH. I could now hear GB3LM, GB3NF and GB3CF at fully quieting. Yes, I know repeaters aren’t DX but they are a good way to evaluate your coverage.

On 2m FM I had many a QSO with local operators as there seemed to be much more activity on 2m locally than there was at the previous place.  This was certainly encouraging.  The XYL and I had also discovered a high point that was easily accessible – the Kirkby Summit Tip – at 193mASL, so one sunny(ish) day in May I went up witht he handheld.  Just using the supplied rubber duck I called CQ /P and received a reply rather quickly from an amateur in Huthwaite (a village on a hill).  We ended up with several other amateurs joining in, some very local and some a little further afield.

It was in May that I started concentrating more on J3E (SSB) on 144MHz,  I took part in the UKAC contest on the 1st – just for an hour – and logged 9 QSOs in both the IO93 and IO92 squares – not too bad with 10W.  Then on the 7th I managed to work a G1UUO/P who was on a SOTA activation.  Conditions were generally lifting with the weather improving now. On the 13th  I worked GB5HW – a windmills on the air SE station from Derbyshire.  On the 20th I had another good day with 5 in the lag from IO93, IO91 and IO81 squares.

Come June we had a combination of high atmospheric pressure and early morning mist.  This gave rise to excellent tropospheric ducting conditions and I managed to work GW1YBB (Wales) in IO81 and PE1BEW (Netherlands) in JO32.  At the beginning of July was the RSGB VHF/UHF Field Day, so I switched the radios on and worked into Scotland, Wales, Eire and most of England over two days on 2m.  I have been rather pleased with my 2m activity thus far.  I have now also added a 144MHz PA and GAS-FET preamp to the setup to give me a whopping 45W when needed.  This gives me an effective radiated power (ERP) of 357.448W with the 11.6dBi gain from the 10 element Yagi.

UHF I didn’t find very effective but this is due to a fault that has developed with the audio stages on the FT-817.  Something I shall have to look at when I get the time.

I have recently started moving towards the microwave bands.  I have built a biquad or backfire array antenna for 3.4GHz (9cm) pictured below.  This is to be matched to a transverter that I am hoping to acquire soon.

37544485_1995067277180029_7062510927232368640_n

Today I took delivery of some 5.7GHz ATV equipment.  It is actually a 5.8GHz FPV Transmitter, a 5.8GHz FPV receiver and a CMOS camera – the type used by radio controlled drone or aeroplane fliers to film video.  The frequency of each is programmable from 5.658GHz – 5.917GHz so I shall pre-set each to 5.665GHz for the amateur radio portion of the band.  I shall build a double biquad antenna for 5.7GHz (6cm) – like the above picture but with 4 Quads as opposed to 2.  This will give approximately 18dBi of gain.  I also hope to find a PA to increase the 600mW output to somewhere around 2.5W. Pictures are below.

 

More will follow on this last piece as I get the ATV system set up and operational.

Making Waves – New QTH and new Challenges

IMG_20180401_094736

Recently we moved from Grantham – IO92QV – to Kirkby in Ashfield – IO93IC.  The Grantham QTH was OK for HF but useless for VHF and above as it was in a dip, totally surrounded by high buildings and 200ft hills containing iron ore.  The new QTH however is 154m above sea level offering great prospects for VHF and UHF – but how to take advantage of them?

The first challenge we faced was the weather.  On the day we moved (27/02/2018) we were hit by the worst snow storm in 20 years which closed off roads and communities across the UK. To add to our problems the heating didn’t work so with sub zero temperatures and no hot water there were other priorities before thinking antennas and such.  Getting an emergency plumber out in those conditions was not easy and it did take two days to do so.

However, I did eventually manage to get up a 14MHz EFHW as a temporary antenna for HF and a collinear for VHF.  I also bought a new 2m radio – the Yaesu FTM3200D so I could see what the digital mode (C4FM / Fusion) was about.  This proved to be quite interesting, providing a very clean signal, but sorely underused.  With standard FM I can now access GB3LM, GB3NF and GB3CF – Lincoln, Nottingham and Leicester repeaters on 2m.

IMG_20180420_095600 The FT-480R 

I also use a Yaesu FT-480R for 2m.  This provides 10W output on FM and CW and 30W PEP on SSB.  For SSB and CW a vertically polarised antenna is not much use so I needed to raise my 10 element diamond Yagi form the garden to a good height .

IMG_20180405_150406_676 UHF and VHF Yagi antennas in garden 

Obviously, not having a suitable ladder for the task I called on the services of a local antenna installer who came round and duly fitted it up on T and k brackets for me.

IMG_20180409_170222_766 Above the roof now… 

With the antenna in this position I have managed to work into Scunthorpe (North East) and Wales (South West) on 2m SSB. I also have a 13 element Yagi (DL6WU) for 23cm but that has yet to go up.

For HF I am using an HW-40HP OCFD at 8m AGL – this is about 1.5m below my 2m/70cm collinear.  When (if) the rain stops I am also going to set up a long wire for 80m.  The garden is a little over 20m in length so this should be quite easy.

IMG_-yyscmf The Collinear with the HW-40HP below it.

Making Waves Power supplies.

November 10, 2017 Leave a comment

I was sat wondering what I should propose as a winter project this year – after all we all know how these winter months can drag on with long nights and cold wet days – and looking through some old notes I have decided on building myself a new PSU.  We all know the importance of having a good PSU in the shack, whether it be a switched mode type or linear regulated type, to power our radios and various peripherals.  I personally don’t like the switched mode ones so very much as they do tend to be rather noisy in the HF spectrum where most of my activity occurs.

So a standard linear regulated power supply it will be then.  Surprisingly very few components are needed for this although a good metal case with ventilation will be a must.  Let’s look at a layout plan.

Rectified_PSU_transformerfig.1

In its simplest form A is a fuse unit for the input to prevent any mains surge from damaging the transformer, B is a double wound transformer to convert 240V to 12V (still AC), C is a full bridge rectifier and D is a smoothing capacitor.  The output is then 12V DC.

With the above assembly we should expect to see the following outputs when measured on an oscilloscope:

AC_Sinewave fig.2 AC sinewave.

The AC sinewave should be seen at the output terminals of the transformer.

Rectified_Waveform fig.3 rectified AC

Tis is what we should expect to see at the output terminals of the full wave bridge rectifier.

Regulated_DC_Output  fig.4 Regulated DC output

And this is what we would expect to see across the output terminals all being well.

Obviously, the size of the transformer depends on how much current you wish to draw and an inline fuse between the unit and the equipment you will be powering will also be necessary in case of any surges (or faults with the equipment).  I shall now attempt to source components and will report back later with progress.

 

Making Waves – 2m Quad

October 16, 2017 Leave a comment

The M0CVO High Gain 4 Element Quad for 2M

The antenna I am now going to describe is one that I designed some time ago. It is a high gain quad beam for 2M (144 – 146 MHz) band. The forward gain of such an antenna is approximately 11.5 to 12dBd, that’s approximately 10.6 to 10.8 times the output power from the rear of your transmitter. For example, say you were operating a 10 Watt txr, the effective radiated power (erp) would be 10*10.6=106 Watts.

All this power and still a relatively small antenna; the boom is a mere 1 metre in length and may be constructed from 1” (2.5cm) square, weather treated, wood. The elements are constructed from 2.0mm diameter enamelled copper wire (ecw), the dimensions of which are shown in Table 2.

All the dimensions were calculated using the formulae in table 1, which was, admittedly gleaned from “The Amateur Antenna Handbook” by William I Orr, W6SAI, although the beam is of my own design.

Table1

Polarisation
For horizontal polarisation feed from bottom for vertical polarisation rotate by 90◦

Table2.PNG

Fig 16

To strengthen the elements of the quad a 2nd support can be fitted which will also make it easier to attach to the boom.