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.

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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.

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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 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.

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. 

 

Making Waves – Antenna Polarisation Issues

June 8, 2017 2 comments

 

Someone asked me to explain why he was unable to hear some horizontally polarised stations on his vertical even though the vertical operates at 360degrees.  This was the explanation I gave him:

Dipole1fig.1

Fig.1 shows the radiation pattern of a 1/2 wave dipole, showing strong signals off either side with nulls towards the ends.

Dipole2fig.2

This is better shown in fig.2.  Assuming that the antenna runs from north to south in a straight line, any station to the east or west will be able to hear / work it but if they are located north or south of it they will struggle to hear or be heard.

Vertical1 fig.3

fig.3 shows the radiation pattern of a vertical antenna.  A vertical antenna, when placed over a good earth, will radiate evenly in all directions and so can be heard/worked by any station in any direction that is either vertically or horizontally polarised.  However, those who are horizontally polarised must have their antenna running in the correct direction for the reasons outlined above.  There is also a 3 – 6dB loss in signal due to the change in polarisation although this effect is only true in a vacuum as scatter caused by other objects and reflection changes the polarisation of the radio waves anyway.

 

 

 

 

 

 

 

 

Making Waves, 23cm and infinity

As I have stated previously I purchased a 1296MHz transverter from SG-Lab in Bulgaria.  Anyway, upon applying power to it and testing the transmit (with an IF of 145MHz at 2.5W from my FT-817) I noted that it was not working as described.  Upon opening up the top of the case I noted that one of the components was raised and obviously burnt.  I contacted Hristiyan, LZ5HP, at SG-Lab and sent photos of the faulty component in situ.  He immediately identified it as a short in the choke having caused the problem and I returned the unit to him.  Two weeks later it was back with me in full working order with a replaced choke.  This time when I applied power and some IF it worked as it should.

I also mentioned that I would look at constructing a DL6WU Yagi but, unfortunately, work has got in the way and I just haven’t had the time.  I looked online for suppliers and, after much deliberation, decided to purchase one from Dual Antennas in Serbia (www.antennas-amplifiers.com).  This was down to both price and quality.  Although there are manufacturers both in England and in Germany, Dual seemed to offer the best deal.  For a 13 element Yagi it cost me 59€ plus shipping.  there was the other issue that when it arrived in the UK it was held by customs for a week whilst they added import charges and VAT but that only came to £19.15.

23cm-Yagi--Antenna-Rear-Mount-PA1296-13-R-420x200The 23cm Yagi from Dual.

So now I am fully operational on all bands from 80m – 23cm (except 4m currently).  I have not yet had a QSO on 23cm although I have put out a few CQ calls, so maybe next Thursday evening during the UKAC contest.

23cm Yagi

The 23cm Yagi up at CVO Towers

M0CVO QRP Setup

The transverter visible in operating position below the X1M HF QRP set with the FT-817 providing the IF to the left.