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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.

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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 – 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.