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Making Waves -Break downs and silver linings

It all began when something went wrong with my trusty Yaesu FTdx1200.  This being my main HF/6m radio what was I to do?  The screen had gone from displaying all the necessary information to enable QSOs to be made to simply being the white screen of death.

Pic1Fig 1. The Yaesu FTdx1200 white screen of death

Well, I tried doing a full reset but no change, I opened it up and reinserted all the ribbon cables relating to both the screen and the FFT-1 unit but still no change.  So it was time to first contact the dealer I had bought the radio from originally (5 years ago).  They told me that it was probably a screen fault and that the screen would need replacing at a cost of £167 plus labour at £60/hour. So I then phoned Yaesu UK who told me pretty much the same. OUCH!

I ordered a USB to RS232 (9 pin) cable from eBay to see if a software update would cure it. I also found an ICOM IC-746 on auction currently at £299, I put in a maximum bid just in case and, in the meantime, set up my stand by radio for HF – the FT-817ND.  I turned it on and tried to copy some CW but after the lovely DSP features and narrow filters available on the FTdx1200, it sounded like someone had left the barn door open and there were a hundred stations all working on top of each other. Not good at all.

In the meantime, the USB to RS232 lead arrived but, to my chagrin, was the wrong gender – I needed a female RS232 head and this was a male one.  So I ordered another, the other way around.  Whilst waiting for the new cable to arrive I watched the price of the IC-746 rising as others put bids in over the days.  None of them came to the level that I put in originally though and suddenly I am the winner of an eBay auction  for what was one of the radios I could only have dreamed of owning when they were available (very expensive back then).  The price – £344 plus £30 shipping, £374 altogether. So, I scrabbled around in my piggy bank for loose coins and paid for it.

The new (to me) IC-746 arrived five days later complete with a pair of headphones.

Pic2Fig. 2 The IC-746 

I now had to find somewhere in the shack to set it up..

It is a little smaller than the FTdx1200 but still weighs in at 11Kg so |I looked to set it up on the second bench in the shack.  Now this radio would give me something that the Ftdx1200 didn’t have – 100W output on 145mhz as well as HF/50MHz.  I do enjoy operating on 2m SSB and CW but I had another problem following the storms that struck the UK during February my rotator on my VHF mast has broken – it won’t turn so is fixed beaming south west. This will be a job when the weather improves as it means going 8m up a ladder in a tight spot. However, I did manage to find room for the IC-746 and get it set up for 2m using the beam.

Pic3Fig.3 The IC-746 running 144mhz USB and a FRG-9600 RX receiving local airport traffic.

Then the new USB-RS232 cable arrived, so I plugged it into both my laptop and the CAT port on the rear of the Yaesu and logged onto the yaesu.com website.  Following the instructions on the software update page I turned on the radio whilst pressing both the up and down arrow keys and presto – it came back to life.  Wow, that could have been an expensive repair for the sake of a software/firmware glitch! So now I have two HF sets and one good QRO VHF set.  The ICOM does seem more sensitive than the Yaesu at picking out weak signals on SSB and CW but misses out on some of the nice features of the Yaesu which is more a SDR than a traditional radio.  The ICOM does have a scratch in the centre of the screen but I can live with that.  How will they be used? Well, I will use the Yaesu for CW and contests on HF as I have it plugged into the linear amp whereas the ICOM will be used mainly for VHF and, once I get a second antenna up for HF, can be used for dual band monitoring.  I am currently using an antenna switch to switch between them so I can compare them both but this is never the best way.

73 until next time, M0CVO

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

December 21, 2019 Leave a comment

2

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.

Building Block kits

As radio amateurs we all love to build kits – maybe a test meter, maybe a small receiver or whatever but, if it is home built it is something we can be proud of.  With this in mind, M0CVO Antennas designed the VXO Oscillator kits way back in 2017.  I their simplicity these are based around a Colpitt’s Oscillator and provide a sine wave output that can be followed by a mixer by other modules to create a small transmitter, a receiver (Direct Conversion) or many other things where a stable known signal source is required.These became popular in the UK for Foundation Licence radio amateurs who wished to advance to the Intermediate Licence, part of the course for which entails building a kit that would/could be useful in the radio shack later.  They are currently available for either 40m (7.030MHz) or 20m (14.060MHz).  Both of these are available from HERE. This kit, whichever frequency you choose, is the BB1 kit or Building Block #1.

untitled The VXO Oscillator.

Moving on a couple of years, M0CVO Antennas has now developed and released the second building block kit – the BB2.  This is a class A follow on/buffer amplifier.  Similarly to the BB1 kit is is rather simple in construction, the idea being for self learning in electronics so it can be built by anyone, whatever their level of electronics experience.  They are supplied with PCB and all components needed to build the unit but the constructor must supply their own enclosure if they require one.  All inputs and outputs are via MOLEX connectors.

20190509_135308  Completed BB2 Kit

If a crystal oscillator or VFO is used as the input (eg the VXO Oscillator Kit) this will increase the output signal power to ~1W depending on input voltage (9 – 12V DC).  A couple of these have been constructed and tested as can be seen in the following images:

20190511_091550 20190511_091539 20190511_091534 Under test

The fourth MOLEX connector at the top of the board is for either a switch or a CW Key.  It can be used in its complete state, with a suitable signal source, as a QRP(P) transmitter.  However, suitable filters (band pass or low pass) must be used and a suitable antenna must be connected.  Also a relevant amateur radio licence must be held in order to use it thus. These are available from HERE.

Build Yourself a 40/80m Antenna For Small Gardens Part 2.

January 14, 2019 3 comments

After writing the previous article on the small antenna for 40 and 80m HF Bands I was asked by several people for photographs of the antenna in question.  Therefore I have done this article as a follow on with pictures.

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Firstly you need the coil to be wound.  This one is 78 turns for 1mm ECW on a 41mm diameter former (plastic pipe) at 140mm long.  The screws hold the wire in place as described in previous blog post.

20190114_140408

Then you take two lengths of wire – one at 10.14m and one at 2m (or longer – I cut this one at 2.5m) and attach them either side of the coil.  Tape the longer section to a fibre glass fishing pole using insulation tape and allow the other end to lay loose beside it.  raise the pole and tie the hanging end off to somewhere convenient – I used the fence.

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A better picture of the coil on final position.

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Use of choc block to attach coax cable – second wire is a 10m long earth wire.

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The earth wire is just run around the garden.

20190114_144623.jpg

Final test using an AA30 antenna analyser shows the SWR at 3550kHz – just in the right place for a spot of CW DXing. Obviously , if you wanted the sweet spot higher, use a shorter length of wire at the end.

Build yourself a 40/80m antenna for small gardens

So, you’ve just got yourself a licence or a nice new HF transceiver and are hoping to be active on the lower frequency bands of 80m (3.5MHz) and 40m (7MHz) but are a bit concerned about how much space you will need for an antenna.  After all, an 80m dipole is going to be around 40m (132Ft) long and modern postage stamp sized gardens just can’t accommodate this.  So I am going to describe a single antenna for both bands that should fit into most gardens.

What will you need?  Well, firstly, you will need approximately 40m of insulated copper wire – the sort used for lighting circuits (single core, stranded), usually available from your local DIY or hardware store.  Also you will need a reel of 1mm enamel coated wire (ECW)this is available from RS Electronics – part number 357-788 – some choc blox (cable connectors) or powerpole connectors (available from www.sotabeams.co.uk), a fibre glass telescopic fishing pole – 10m would be ideal but anything from 7m up should suffice, a piece of 40mm drainage pipe (this will be either 41mm or 43mm outside diameter), some 4mm * 20mm machine screws and nuts, some 4mm ring crimps, a length of fishing line (fairly strong stuff 20kg strain or more), cable ties and a length of angled aluminium, or brass – also available from you local DIY or hardware store.

Directions:

Firstly cut two lengths of the insulated wire – one at 10.14m and the other at 2m. Strip a few mm of insulation from each end of the longest piece and from one end of the shorter piece.  Fit crimps where you have stripped insulation on one end of the longer wire, leaving the other end bare (you may wish to tin the bare end with solder) and on the stripped end of the short wire and solder them on for a stronger fitting.  These are going to make up your radiating element.  Put them to one side and we shall come back to them later.

Now saw a 140mm length of the 40mm pipe.  This is going to act as a coil former.  Measure in 1cm (10mm) from each end and drill a 4mm hole. Now rotate the tube by 90 degrees and drill another hole 10mm in from each end.  Scrape the enamel off the end of the 1mm ECW and thread it through the 1st hole on the left hand side of the piece of pipe.  Fit a crimp connector to this end and solder it for a stronger (and electrically better) connection.  Locate the ring beneath the second hole on the left side and push one 4*20mm screw through both and fix with a nut.  This now securely anchors the wire at one end.  Now wind 78 turns of wire onto the coil, you may wish to use insulating tape to hold the wire whilst you are winding it and once you have wound the 78 turns on.  At the other end, cut the ire long so there is plenty spare and thread it through the 1st hole at the right hand side.  On the inside of the pipe measure the wire to the second hole and make a notch/fold here.  Pull the wire out straight, cut it and scrape the enamel off.  Fit a crimp and again line the ring up with the hole and push a screw through, fixing with a nut.  This coil will act as an inductive load for 80m and a trap for 40m.  You may wish to wrap the whole coil in insulating tape to protect it from the elements.

Now take the 10.14m length of insulated copper wire and cable tie it along the length of the fishing pole with the bare end at the bottom.  Make sure the pole is fibre glass and not carbon fibre or graphite as these will affect the tuning of the antenna.  Start about 1Ft (300mm) up from the bottom of the pole.  The other end of the wire will be beyond the top of the pole, don’t worry about this, it needs to be.  Now at the far end of the wire, fit the crimp over the top of the screw you anchored the first end of the ECW to when you started winding the coil.  Fit another nut to secure it (you may fit an extra locking nut if you wish).   Now fit the shorter length of wire to the other end of the coil in the same manner.  Loop the end of the wire back on itself (about an inch) and secure with cable ties. Thread one end of the fishing line through this and tie off well.

1040_sch

Schematic of wire antenna.

 Dig a small hole in the ground (the depth should be half the length of the piece of angled aluminium/brass that you have) and stand the piece of angled aluminium/brass in it.  Fill the hole back in and check that it is secure.  Raise the fibre glass pole to vertical and secure it at the bottom using cable ties (or whatever) to the portion of aluminium/brass that is protruding from the ground.  Using the fishing line that you fitted to the top end of the wire, pull it out to an angle between 30 and 40 degrees and tie the other end off to a fence or something secure.  You now have the basis of your antenna and I shall now describe how to feed the antenna with RF and get on the air.

Fit a choc block (or powerpole connectors) to the end of your coax – it will need to be a double connector for both the inner and earth/braid.  Then connect the inner side to the wire of the antenna and add one or two 10m counterpoise wires to the other side of the outer.  If you have space lay these out at right angles to the vertical antenna, if not, don’t worry, they can be laid in spirals or bent to fit in, it is the electrical length that is important.  You could also connect a short wire to a copper ground spike and lay shorter radial wires out from this.  Take the other end of your coax back to the shack and fit a PL259 plug.  This will attach to your ATU or radio.  Check tuning on low power (5W or less) – it should be resonant on 40m and 15m (3rd harmonic) and a small portion of 80m (remember it is loaded for 80m so possibly won’t cover the whole band.  You can adjust the length of the end wire to match it where required, or use your ATU.  Make sure you insulate the choc block/powerpole connectors to protect from water ingress.

You now have a 40m vertical antenna (as far as the inductor) and an 80m inverted L.  This will give you a near omnidirectional (all round) radiation pattern with a low angle take off so will be good for both nearby QSOs (depending on propogation and atmospherics) and low angle DX. Have fun.

73 DE M0CVO

 

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 2 comments

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.

Making Waves – The Shorty Forty

September 17, 2017 Leave a comment

I was taking part in a Twitter conversation today with someone building the helical antenna published in this month’s RadCom, the RSGB member’s magazine, and having issues with the matching of it.  He was trying it out due to lack of space and a poor earth (clay) at his QTH.

I set to thinking and remembered an antenna design that I used to hand out to Foundation and Intermediate Licence trainees when I was mentoring them through their studies and assessing their practical assignments.  This was the Shorty Forty antenna because we don’t all have the requisite 20.28m of free space to string a dipole across.  I shared the plans with him and later thought “Why not share them for everyone?” so here goes:

The Shorty 40 – Helical Whip for 7MHz

So you want to get onto 40m but don’t have room for a dipole (20.28m)? Then this could be just the answer if you have a little time on your hands and enjoy home construction.

The Shorty 40 is a helical whip for 40m wound on a 3m long, 32mm diameter piece of PVC tubing (the sort available in most DIY stores). You will need 21m of 1.2mm diameter enamelled copper wire, 80cm of 2mm diameter ECW and 10 or 15m of 1.5mm diameter insulated copper wire (the sort used for lighting circuits or earth wire). You will also need a SO239 connector and a piece of angled aluminium.
ShortyForty

The picture says it all really but, just in case, begin by winding the 21m of copper wire along the length of the pipe, using tape or adhesive to secure it along the way. Cut the 80cm of 2mm ECW in half and push through the holes drilled in the top of the pipe. Solder together in the centre and solder the end of the coil here also. Drill a 16mm hole in the aluminium bracket for the SO239 socket and then attach it to the pipe using machine screws. Then solder the other end of the coil to the centre pin of the socket. Connect pipe to mast and connect two or three 5m radials to the solder lug on the aluminium bracket. Attach coax, raise mast and away you go.

Disclaimer  I cannot claim to be the first person to develop an antenna such as this but I have researched ideas on the internet and in books on the subject – from ARRL, PW Publishing and RSGB publishing – and changed them to suit modern metric measurements and make them easier to understand and build.