Making Waves -LoRa and Patch

 

Due to one thing and another it seems that I have not had a lot of time on my hands to do much radio activity for a while.  The sun was spotless for some time during the month of July and conditions on HF literally bottomed out.  Luckily this all seemed to change in time for the IOTA Contest on during the weekend of 30 – 31st July.  Suddenly there were spots on the sun a decent MFI and all bands opened – right up to 2m.  There were intercontinental contacts to be had throughout the HF bands up to and including 10m (28MHz) and quite a few 6m hops although these were probably more down to sporadic e’s rather than multi-hop F2 Layer propagation.

Anyway, during the month I have been experimenting with antennas for 23cm (1297MHz) and 13cm (2321MHz).  I have looked at various designs from the double quad antenna, More details of which can be found HERE to the slot antenna, which can be read about Here and the IFA Patch Antenna, which you can read more about HERE.  I finally settled on a version of the IFA antenna as this was easy to etch onto a piece of single sided PCB with an FR-4 backing.

Mini VNA readings of 23cm IFA Using MiniVNA Tiny to determine properties of 23cm IFA Antenna.

Once I was happy with it I 3D printed a case for the antenna to fit into and checked that the VSWR readings remained below 1.5.

IMG_20160724_125958 IFA Antenna in 3D printed case.

I also looked at the Vivaldi antenna details of which can be found HERE which would make an interesting broadband antenna that could be used to feed a dish, but decided against it at present.

On Friday 26th July I was lucky to receive notification that I had won a pair of RF Solutions LoRa modules in an online competition.  I promptly received these on the Saturday and set about trying to work out what to use them for.  They are effectively a voltage controlled pair of transmitters/receivers and can be encoded to work as remote controls, provide remote networking, remote switching or act as remote sensors.  The range is up to 16km using spread spectrum technology at 868.5MHz.

CocRLbSWAAA2P4B The RF Solutions Ltd Gamma LoRa pair

I am currently experimenting with them as a remote wireless sound activated switching system.  More details on this at a later date.

CorSENhXEAA2w8b Sound Activated wireless switch..

 

 

Making Waves – HF Conditions….

June 19, 2016 1 comment

I read with interest a letter in the latest issue of Radcom entitled “HF Conditions – If only!”.  In it the writer laments over the lack of DX opportunities available on a daily basis as compared to how it was when he was an SWL 40  – 50 years ago.  I could also speak of similar things.  When I got my 1st licence in the late ’90s (VHF only B licence), we were at the peak of Solar Cycle 23 and  144MHz was like 20m is nowadays and there was always DX to work.  When I took the 12wpm CW test and got my current HF licence in 2000 we were still being blessed with excellent HF conditions and I managed to work amazing DX suing just a base loaded magnetic mount antenna for 15m sat on top of the ATU inside the shack – at night too!  The peak of solar cycle 24 was nothing to write home about though and the peak has now passed.

SolarCycle23

Solar Cycle 23

SolarCycle24

Solar Cycle 24

The above two graphs represent Solar Cycle 23 and Solar Cycle 24 for comparison.  It can be seen that at the peak of cycle 23 (2000) we had a daily sunspot count of approximately 120 whereas at the peak of cycle 24 (2014) the daily sunspot count was closer to 80.  The lower number of sunspots results in more coronal holes in the sun which lead to masses of plasma being ejected towards the earth, resulting in more geomagnetic storms (aurora).  This in turn gives rise to some enhancements in VHF (50MHz, 70MHz) but poor conditions on HF.

Solar%20Cycle%2022

Solar Cycle 22

Looking back further to Cycle 22, it can be seen that the peak was even higher with a daily sunspot count above 150.  If this trend continues could it be possible that we are heading for another Maunder’s Minimum where there will be no peak for the complete cycle?  Will this mean a total flattening of the HF conditions?  It certainly would spell bad times ahead for the higher HF bands above 18MHz.  Fingers crossed it won’t come to that and our local star will become a little more active at it’s next cycle peak in 2020/21.

Making Waves–Bakelite and Moving Coils….

I have been rather busy of late so haven’t had so much time to play with anything radio.  I did, however, manage to pop into the local antiques dealer (Notions) and take a look around.  Amazing what fascinating stuff you can find in these places.  What I did find (and purchase) was three moving coil meters (milliamperes and microamperes) in Bakelite cases.  One dates back to WW2 and was for military use and the other two are just post war.  All are made by English manufacturing companies (unfortunately no longer in existence) with the quality one would expect from this era.

IMG_20160512_154752 The three moving coil meters.

20160522_083809This is the one from WW2.  The K in the centre of the dial above an arrow denoted it as military.  The range is 0 – 150mA and yes, it does still work and is accurate to +-1%.

20160522_08464720160522_084709 

This one is of interest in that not only does it have a more visible dial and a manufacturer’s name – Crompton Parkinson Limited – it also has a completely clear cover enabling the workings to be seen.  The internal resistance of 5Ohms is clearly marked on the front so this can be included in calculations for power and current.  Admittedly, with a full scale deflection at 15mA you are not going to be testing any high power apparatus with this.

Researching Crompton Parkinson Ltd, I discovered that Crompton & Co. was a lamp manufacturer founded by R.E.B. Crompton in 1878 and F & A. Parkinson Ltd. was a successful electric motor manufacturing company.  They also purchased Vidor Batteries – a manufacturer of flashlight and radio batteries – and Burndept Wireless.  If you follow this link: Wireless World 1925 it will take you to a pdf copy of a page from Wireless World, September 30th 1925 describing some of the valves made by Burndept.

Burndept

Making Waves–Key bashing and other escapades….

Well, yet again I have found myself pushed to make time to spend on the radio.  Looking back through the pages of my log book I see many QSOs using CW, the occasional JT65 and even more infrequent PSK31 or PSK 63 one.  J3E seems to be a tad rare (I count about 5 during this year so far.  I must admit, I do prefer to use the key these days and find that I can get my signal so much further with so much less effort and power.  Yes, I spent my money and bought the MD-200 desk mic from Yaesu to accompany my FT-DX1200 but it sees so little use. Aesthetically it does look nice though.

yaesu-md200_web1 The Yaesu MD-200A8X Desktop Microphone

Yesterday I was pleased to manage a QSO with JT1CO in Mongolia for a new DXCC country.  This was using 90W of CW into the MQ1 mini-beam on 15m (21MHz).  I also managed a couple of Russian contest stations on 15m yesterday.  I must say, it is good to hear some of the higher bands opening up again.  I tried 12m and 10m but the only openings on these appeared to be between stations near the equator and nothing was heard this far north.  the 50MHz (6m) band should be coming to life soon with the sp-e season but the SFI is still too low for it here and for the brief period that it is open most of us will be at work or otherwise engaged when the real DX is happening.

Earlier in April I managed to work many of the Yuri Gagarin special event stations on CW celebrating 55 years since his 1st space flight.  Following that I managed several of the HG225 stations for Samuel Morse.  I didn’t get all of them though so no award for that one.  I did receive my CQWW CW award for my entry into last year’s contest though which is now hanging proudly on the shack wall.  Maybe it is not the highest score in the world (#6 in the UK) but for 5W into a wire dipole I was pretty pleased with it for a first attempt. Single Op QRP Unassisted.

CQWW Award CQWW CW Contest.

I have also been busy designing my next project.  1st prototype boards have been etched – now I just need to cut them to size and drill them.  The latter will require a very small drill bit (0.6mm) and either a steady hand (ahem) or a drill stand.  I do have a drill stand so this will probably be the way.  I am attempting to build a transceiver in stages to cover the main amateur bands (40, 20, 15 and 10m).  The oscillators used are simple Colpitts form and the next stage is the buffer and keying circuit.  The boards are pictured below for the 2nd stage.  I shall then move on to final amplifier (to 5W) and band pass filters for each band.

20160426_145742 PCB’s created in the CVO Lab.

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Making Waves Radio and Electronics

It has been a bit of a rough ride lately for my radio antics.  Last weekend was the international WPX contest which I was looking forward to being involved in.  Unfortunately we also had an issue with Storm Katie – a deep low pressure system with extremely strong winds and heavy rain.  So the antenna mast was lowered and then luffed over and tied down to protect it against the weather.

Luffed

 

Therefore I was, unfortunately not able to take part.

However, whilst it was down it did give me the opportunity to tighten up a few nuts and straighten my 2m Yagi – was pointing in the wrong direction.

It was the 25th March before I had the chance to raise the mast back up to vertical again and without extending it fully (half height) I managed a quick QSO with E74X on 20m CW.  Looking at the log book I haven’t really had much chance to get on the air much – SN7D on 26th (J3E), LZ1QI on 29th (CW), YU7MK on 31st (PSK63) and then RW55YG (Yuri Gagarin Special Event) on the 1st April using CW at 30wpm.  Not a speed I use very often but glad I can at times.

Back Up

The mast back upright clearly showing the M0CVO Antennas 1:1 BALUN used at the feedpoint of the MQ-1 mini beam / hybrid quad.

I have been spending some time (whilst the mast was down) designing a few little QRP circuits.  Amazing what you can do when you look in the shack junk box and find a few spare components.  You may hear some faint CW populating the airwaves around 7.030MHz (+-) with my call latched onto it.  This is less than 1W (about 500mW) so not sure if you will hear  me but please do listen out.  I promise to keep it slow (straight key around 12 – 14wpm). More on this one another time though.

Have the gas engineer round now to service the boiler so will sign off and say 73.  Till next time…..

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Making Waves–White Noise and Woodpeckers

Well, here we are, half way through March 2016 and looking forward to the sporadic e season on the 6m band.  Quite looking forward to some 6m DX this year now I have the hybrid quad up.  However, currently when listening to the 6m band all that is heard is white noise.  Nothing, it seems, is getting up this high in the Northern Hemisphere as yet.  Will keep monitoring it though as you never know when something may break through – especially on the magic band.

Then we get onto woodpeckers.  Pretty little birds that tap the bugs out of tree trunks and nest in holes but very little to do with radio… Wrong woodpeckers, what we are speaking of is the Over The Horizon Radar (OTHR) that keeps popping up on 15m at the moment.  In the past both Russia and China have been guilty of using high power OTHR on the amateur bands producing that familiar tapping / knocking sound but now I believe the UK and the USA are as guilty.  Anyway, on Sunday afternoon I was trying to work a station from the Democratic Republic of Korea (nice DXCC) when up it came and totally wiped out the portion of the 15m (21MHz) band being used.  This has been heard on other bands also and was commented on by some twitter users at the weekend.  So much for international IARU agreements banning the use of OTHR in the amateur bands. 

Have been busy designing some 5th Order Low Pass Elliptic filters for 40m (7MHz) and 20m (14MHz).  These are done with SMD technology – coils with a physical dimension of only a few millimetres in length and 1.2mm across. Whilst certainly not aimed at the QRO operator they will be fine for very low power (QRPP) transmitters such as those used for WSPR or QRSS beacons.  It is an ongoing project at the moment so no photos of completed units but I do have some graphs – one of which is at the bottom of the page showing the 7MHz filter properties. 

IMG_20160314_104700

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Making Waves: DX Power

March 5, 2016 1 comment

For many years now I have been a radio amateur.  I started out in the 90’s as a B licence holder (M1DKN) (VHF, UHF and above) and then, in 2000 took and passed my 12wpm Morse test and gained my HF licence (M0CVO). 

As M1DKN I enjoyed some relative DX from difficult locations building and using quad yagi antennas and ZL Special antennas, once managing Cromer (Norfolk) to Moscow via strange tropospheric propogation and Cromer to Caithness Lighthouse via auroral scatter.  Being limited to VHF and above certainly encouraged one to learn as much as possible about weather systems and phenomena to enhance communication.  Getting as much power into the antenna and then out of the antenna into the air was also crucial so one made sure that the coaxial cable or feeder of choice was of the highest quality and lowest loss.  It also gave one encouragement to build and test various antennas to obtain the highest gain and best results.

Then I got my HF licence and this opened up the rest of the world for me (as far as spectrum went).  Due to restrictions (garden size, local authority, planning, etc.) I have always limited myself to wire antennas that could be called “stealthy” but I still managed to work most of the world even though it was sometimes a struggle.  This proved easier to do using CW (Morse) or, occasionally, other data modes such as PSK or JT65.   However, I was never really set up as a DX station.  Recently I looked at the situation and decided to give something new a try.  So I obtained an HF beam.  Actually, it is a mini-beam as I would not be able to fit a full size HF beam (even for 10m) in my small garden without it overlapping the neighbours’ properties on either side.  The beam in question is the TGM Antennas MQ-1.  This is a four band beam for 20m, 15m, 10m and 6m.  The longest element is 11ft (3.35m) and the boom is 4.5ft (1.37m).  The reflector is a hybrid quad element in a diamond shape that stands 48” (1.22m) high.  Tuning is done with a series of coils and capacitor caps consisting of adjustable spokes.  Total weight is 16lB (7kG).

IMG_20160304_134022 

The MQ-1 in place beneath the 144MHz 10element Yagi

Performance wise it is astonishing.  First contact was with NC1I at 57 / 59 on 15m and then with VE8EV on 20m (59/59).  The quoted gain figures are:

6m: 6.5dBd, 10m: 6.0dBd, 15m: 5.5dBd, 20m: 4.4dBd.

Going by the performance and comparing with a straight dipole I can well believe that they are correct.  So now I have a good DX setup and with the 300W linear that I occasionally use should be able to work some of those rarer stations.

Have a good weekend and good DX.

73 DE M0CVO.

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