RSGB 2nd 144MHz Backpackers contest 2016

The 2nd event in this series of contests coincides with the Practical Wireless QRP contest so we decided we would do both. This contest starts earlier than most of the other Backpackers event so it was an early start for us, or I should say even earlier.

The weather this time was fairly poor. Lots of rain and quite windy. So we arrived on the top pretty soaked through with terrible visibility and a pretty dense low cloud.
arrived at the top
The summit site is pretty exposed so if there is any wind at all anywhere, it’s usually very windy on the summit. We were ready for this though. The lightweight mast I have built was made in 3 sections and purposely designed for such an occasion. For lower less exposed use in contests where we are OK to use its full length all three sections are extended and we have a set of guys for each section. (the lower guys are really only there to hold it up while we extend it etc). But for the backpackers series section 3B we are only allowed 4m high, which just so happens (it was designed that way really) to be the height with the mid section extended. This means we have the option of double guying the highest section of the mast. We have separate pegs for every single guy as this negates the need for knots and saves us set up time by just putting the peg in the loop, and putting the peg in when the guy is taut. This also means on a 4 metre mast we have 8x 550lb breaking strain guys on 8 decent sized pegs, so despite the scary wind noises when inside the tent the antenna is pretty safe.
Double guys shown here (one on left is the lowest set up guy going to a tiny tent peg):
set up double guyed
Once in the tent we were pretty cold thanks to the liquid cooling we were enjoying. We’d allowed plenty of time to deal with any unforeseen circumstances or issues setting up in the bad weather so we had time for a few warming cups of coffee.

Once under way we forgot about being cold and set about the job in hand:
G1YBB operating GW1YBB portable
We got pretty decent activity in first hour or so, and to be honest not bad in the first 4 hours, which is all of the Backpackers contest. However DX was rare we managed a French station at Calais and one Belgian station. It was nice to point to Guernsey hoping to pick some mults up and within 5 minutes we got one, thanks for that! The last 3 hours to make up the PW QRP entry were best described as dire. Without the CQ caller I made I am pretty sure we would have quit and gone home. On the plus side we never heard anyone with a higher QSO count, but PW is a square multiplier contest and I feel we are going to suffer with a low square tally.

There was no post contest looking around and chatting. Radio straight off and try and pack up before the looming black cloud making it’s way towards us arrived. Here we are ready to roll (taking turns holding the mast for the camera):
ready to go home
Paul ready to go
QSO map:
QSO map 2nd Backpackers 2016
Claimed scores:
Claimed scores 2nd Backpackers 2016
Results:
Final scores 2nd Backpackers 2016

Winners of 2nd backpackers 2016
Full result list (PDF)

RSGB 144MHz UKAC 7th June 2016

This session I had company in the shape of Paul G1YFC to help set up and operate. Another pair of ears is always welcome with the weak stations or when we are suffering from QRM from other stations. On reaching the bottom of the ascent of the hill we were greeted by flashing flooding from the lashing storm that was hammering the car. The lower roads where more level had 4 to 6 inches of flowing water over them and even the higher steeper sections were a brown rushing river about 1 or 2 inches deep. This is a picture of the very last section of hill with hardly any catchment area above it:
flash floods on road
Once on site we sat in the car to wait out the heavy rain. It eased a little so we started to put the mast up but the rain picked up and it felt like someone was pouring a hosepipe down the back of my non waterproof trousers so we abandoned ship to the car. It eased again so back out we went and this time it stopped and the sun came out. By the time we had the antenna up we were bone dry from soaked through.
antenna mast set up
We had a few QSOs before the start and fisnished the last rag chew with the first QSO in the contest but found it a slow start. Conditions seemed quite odd and we could hear a lightning strike crash every now and then for most of the contest but we didn’t see any. Paul had time to take an arty low sun shot of me in action:
G1YBB in action
We also had an interested visitor:
interested spectator
Anyway, we got 105 QSOs but didn’t work one single European station not even Frank PE1EWR who always calls us. Although our QSOs were respectable and points per QSO also not bad, we just didn’t have the multipliers.

Our QSO map:
144 UKAC 2016-06-07 map
Claimed scores:
Claimed scores 144MHz UKAC June 2016
And the results:
Final scores 144MHz UKAC June 2016
Full result list (PDF)

RSGB 1st 144MHz Backpackers contest 2016

This was the series of contests I have been building the lightweight and portable antenna system for. I knew exactly where I wanted to operate from and the new (to me) super lightweight Yaesu FT-817 radio and the modern Lithium batteries have made it a possibility for me. Most of my previous contesting in the 80s and 90s was done in the Black Mountains below Pen-Y-Gadair. It is a great site for the non multiplier contests but because we were below the summit we always lost out on multiplier events. I always wanted to operate from the summit but with our equipment then it was a no go for us with no 4WD and even a landrover would struggle to get there.

But I can walk there! Well I can with Paul G1YFC to help carry the gear.

Here I am loaded up:
Loaded up and on the way
And Paul with his load too:
Paul loaded up to go
Nearly at the summit:
Nearly there
The weather today was practically perfect for contesting on top of the exposed summit, unlike the day before when the winds would probably have made it impossible to get my lightweight mast up safely. We managed to get the antenna set up before a light shower and soon had my mountaineering tent up too. We set up away from the summit cairn to be out of the way of walkers but also to be above the steeply falling East facing side of the mountain to make the best use of the ground gain:
antenna and tent set up
Paul took an arty one of my direction label and the end of the coax:
direction label and coax
Once the radio was connected up we scanned the SSB section of the band to see who was about and to find a free frequency. There were some strong fairly local (as crow flies) stations below 144.300MHz so we went higher to be clear of them. I noticed I could hear one station CQing 50KHz away so decided a 100KHz away would be a good plan. Once it hit 11:00 we were off. About 90 minutes later Rob GW7LAS/P popped up and after our exchange informed us we’d kicked off an hour too early. Doh! Disaster. We worked some good multipliers and quantity of QSOs in that first hour, for no avail. There was nothing for it but to soldier on and make the best of a bad job.

Later on we had a sharp rainstorm and with it came S9+ of rain static. So strong the station that we could hear 50KHz off his frequency was only just readable above the noise. Luckily it died back down after a while. The last couple of hours were pretty hard work beaming north for some Scottish points proved fruitless as did beaming to Eire. We did beam down towards Guernsey hoping for some GU and maybe a French station that seems to be on often in the UKAC events and were pleased to pick up Guernsey and Alderney almost straight away.

We finished with 121 QSOs of which 79 were in the qualifying period. We lost 9 multipliers from 6 QSOs in that first hour alone! However we managed to salvage a reasonable claimed score of 783,300 points which put us just in 2nd place in our section. One more average QSO would have taken us to 1st!

Here is our QSO map, valid QSOs in green, invalid in red. We lost some good distance ones and multipliers too:
QSO map scoring and non-scoring
Our claimed score was encouraging though. Hopefully Rob GW7LAS/P made more logging mistakes than we did, one decent lost QSO more than us would mean we would swap places:
claimed scores 3B section
Results showed we couldn’t overtake Rob after all. So close yet we could have done so much better. BIG lesson learnt there!
results 3B section
Full result list (PDF)

RSGB 144MHz UKAC 3rd May 2016

For this next session of the the UKAC series I decided to use an old site that was the site of my first ever 144MHz VHF contest when I entered the PW QRP contest with Kevin G1VDF. I chose to operate here as I was hoping to get back earlier as getting into bed at 1am on a work night was a bit late. The drive is slightly longer but it is a drive on site so packing away hopefully would be quicker.

Where I decided to set up was a little cramped and awkward to raise the mast on my own so it took longer than it could have. However I did manage to get all set up and on air a little before the kick off although with no real spare time for any photos this time.

I could hear some seriously strong stations giving me some interference so I tracked them down to check they weren’t in the field behind me or something similarly close. They weren’t but they did report I was giving them issues with splatter and sounded like I had far too much compression on my audio. This was the first time out for my new build of the BX-184 CQ caller which I suspected might be set too high in the mic. As I didn’t have the right tools with me to do anything about that I tried to cut down the overdriving by turning down the SSB mic gain down a fair way. This was said to help but not solve the issue completely, though I was receiving the complaining stations so strongly the signal reading never came off the ‘stop’ between their words even. I changed my operating frequency for a further 10KHz away from them to try and help.

Once under way activity was quite good as last time but generally although signals all seemed to be really big I didn’t really get as many more distant stations. I’d hoped to make use of the ON4KST chat like most do for finding multipliers but I was not getting any cell coverage to get online which was a shame. I did manage to find two new GI squares searching and pouncing though again missed some other ones. It’s tough to know how long to spend away from the running frequency searching and pouncing!
My QSO map for this contest:
144 UKAC 2016-05-03 map
My QSO count was 2nd highest and my claimed score put me in first place in the low power section. However it was close at the top and adjudication could easily scupper that:
144 UKAC 2016-04-05 claimed scores
The results came in quite quickly this time and I was pleased to see I was still top out of the 85 entries in AL section! I lost 5 QSOs for errors but luckily others lost some too and I stayed top:
144 UKAC 2016-04-05 final scores
Oh, and I was in bed by 11.45pm, result!

Full result list (PDF)

Simple car portable operating table

As I have always operated way more as a portable station than a base station I have operated from the car many times and in many ways. Some not as comfortable as others that’s for sure. It gets tiring twisting to one side or hunching over. In the end I came up with a simple solution for me that enables me to easily set up and have space, and be comfortable operating, which is important if you are spending a long time operating like in a contest.

Basically, a plank of wood!

More accurately it is a small sheet of plywood sized and modified for purpose to make a flat table in the car to carry the radio and any ancillary units like batteries, PSUs or amplifiers etc. It’s strong enough to support a 4CX350 based 200W VHF amplifier.

The sheet is sized wide enough to fit in most normal cars and long enough to reach from the top of the dashboard to just past the back of the driver’s seat. There is a slot cut to allow it to slip over the steering wheel:
car portable operating table
I keep it in the boot ready to go as it doesn’t really take any space. I just take the head rest out of the driver’s seat and sit the board on the top of the seat. The slot for the steering wheel allows the board to sit on top of the dash and adds a level of security from catching a sleeve on a corner and knocking it off. In my shiny new car I just add a towel over the steering wheel and dash and another on top of the seat to protect them from any markings. The two head rest entry points and top of the curved dash make a tripod style stable platform. And the weight of the radio and batteries keep everything steady.
I use my backpacking batteries because I don’t have a DC feed at 20A to the car battery for the radio and I don’t have to worry about draining the car battery if a pileup comes my way.

I pull the steering wheel all the way forward to drive anyway, but this means the wood extends back enough to sit normally in the back seat without even moving driver’s seat and I can sit with my back against the back seat (rather than hunched forward) comfortably and operate. In fact these days as you see, I have the tablet on my lap. The most comfortable car portable operating I have found, and I have done a lot over the years!
car portable operating table
This is about the 4th or 5th car this board has seen action in and it is now into it’s 4th decade (with about a 2 decade break).

RSGB 144MHz UKAC 5th April 2016

After hoping to enter the previous two sessions of the RSGB 144MHz UK Activity Contest series but for various reasons failing to get on the air this time I finally succeeded. It’s 18 years since my last VHF contest. This time I could try out my newly finished and as yet untested on air 9 element DK7ZB yagi and lightweight portable mast.

I checked the past year’s results to see if my old (from back in early 1980s) site was being used in the UKAC series. As it didn’t seem to be I chose to try there for this contest.

The original plan was Paul G1YFC would also come up for the contest (we won our last contest in 1998) but he couldn’t make it so I slogged up the hill with all the gear on my own to the trig point on Graig Syfyrddin which is at a height of 423m which a clear take off though has the 400m higher black Mountains West of it:
Portable 144MHz station carried up
Literally every radio item I would be using for this contest was new to me since the last contests I did. It was a pretty calm evening so setting up was fairly straightforward and I soon had the mast and tent up:
144MHz portable contest station
Once I had the Yaesu FT-817 connected up and the tablet fired up I worked a few stations before the contest getting good reports from my QRP station which was good to hear. I did learn it’s much wiser to operate from a hill you can pronounce the name of though. One quick check outside before the contest starts revealed a nice sunset:
portable contesting sunset
Once the contest started activity was pretty good. For the first hour or so I was exceeding 1 QSO per minute and getting great reports. Things did slow down a bit and QSOs came in little bursts of activity. I made use of the 2nd VFO for some search and pounce but was mostly running. Logging was done on my Surface Pro 3 using Minos by G0GJV. What I should have done I think was also try the ON4KST chat that everyone uses. It actually never occurred to me on the night. This was a great shame as I missed a couple of leading big gun stations somehow that would have given me some valuable new multiplier squares. Anyway I got 120 QSO in total which seemed respectable.
Here is my QSO map:
144 UKAC 2016-04-05 map
Packing up as quickly as I could by headtorch I headed down the hill almost running at some points. Even rushing it was midnight when I reached the car and 1am by the time I got to bed.

My claimed score (before adjudication) put me in 3rd place in my section. 4 multipliers (2 UK new squares) would have put me top! Missing those big station multipliers was very costly indeed!
144MHz AL section claimed scores
Overall I am very pleased with the first go out this century. It was meant really as a practice run for the forthcoming 144MHz Backpacking series of contests and also the PW QRP Contest which I have always been a big fan of. The equipment all seemed to work well apart from one small temporary issue with the keyboard on the Surface Pro 3 failing to respond which was very inconvenient. I did get it going but without know how or why it stopped working.

Full result list (PDF)

Portable 9 element 144MHz DK7ZB long yagi

As I was planning to resume 144MHz contesting but this time full backpacking style I wanted a decent beam that was suited for repeatedly assembling and disassembling. I have a Cushcraft Boomer and also a pair of homebrew DJ9BV yagis but neither are really ideal for the job. After nearly two decades away from radio yagis have moved on and researched showed the DK7ZB yagis were very popular. His designs seemed ideal for my purpose.

I settled on the 9 element long yagi as it is not too long but with decent gain and also has a good flat SWR curve. The RSGB Backpackers section we wanted to participate in only allows one antenna so stacking shorter yagis was out.
The dimensions are available on Martin DK7ZB’s site:
DK7ZB yagi dimensions
I went for the 10mm elements as a compromise between size and weight and best performance. I was also able to find 10mm clips to suit my intended design.

You can buy some of the DK7ZB yagis ready made and also in kit form, but I didn’t really think the parasitic element mounting methods were ideal for repeated building especially in cold weather. Also the driven element was a problem as it’s not ideal at all for disassembly. There was one example of a driven element designed for taking apart on DK7ZB’s site but I couldn’t find any parts like they were using. I was already building my own lightweight portable mast so I decided I may as well design the yagi from scratch too. So I modelled the full antenna down to every nut and bolt in 3D CAD software. This enables me to know exactly what materials I need and also predict pretty accurately the weight, bearing in mind I plan to backpack this up hills:

To source the main raw materials I found that it was cheaper to buy from https://shop.nuxcom.de/ in Germany than anywhere I could find in the UK! I went for the 20mm square boom and 10mm elements. My 3D CAD model told me I wanted two sections of boom 1.72m long and one section 1.62m long. (After ordering I noticed that is the same lengths Attila uses in his 9 element kits!) I didn’t go for a kit as there were several parts in the kit I didn’t need and I wanted to order a few spares of the elements just in case I cocked up some of the cutting. Nuxcom sell the boom in 1.5m and 2.0m lengths but the 2.0m lengths cost more than double the shipping, so I asked Attila if it was possible to buy 2.0m lengths but have them shipped in two pieces, 1.72m and 28 cm lengths. He did this for me at no extra cost which is good service. The offcuts would be useful for doing tests later.

First building task was to cut the parasitic elements to size. Although I’m pretty good with a wood saw I’m a bit rubbish with a hacksaw and I didn’t want to use a pipe cutter as certainly for the driven element I needed no deformed ends to the tube, so I managed to borrow a mini circular disk cutter like so:
Proxxon KG 50
With this I was able to make nice square cuts. To measure them I used a metre ruler (tape measure for the reflector-checked against the metre rule first) butting both up against a stop to get an accurate measurement. I checked that the first mm was a true mm before starting as some rulers have a dubious first mm:
measuring stop
And checking D2 (ever so slightly short if anything by a fraction of  a mm):
D2 measuring
After cutting the parasitic set I fitted end plugs from Nuxcom for a nice finish. (Elements in bottom box, spare elements and boom sections in top):
parasitic elements cut ready
Next to assemble the boom. I bought the Nuxcom boom joiners and I must say they are very well recommended. The fit onto the 20mm boom sections is a snug push fit and the extrusion is thick enough to be strong yet still light. I got them with the M4 bolt and wing nuts. The one thing I didn’t like so much was the massive hole for M4 which was 6.5mm diameter. However, once I modelled up the joiners and dropped them into the antenna assembly I could see that a 4mm hole at the top of the 6.5mm hole would be pretty much bang on centre of the boom, and mean the boom could not move up in the joiner. I also added a vertical bolt on each side of the joiner too as shown below. That meant the boom section was forced into the joiner tightly ready to drill the holes. I drilled from each side, using the 6.5mm hole as a stop for the 4.0mm drill bit:
boom joiner
The above picture is showing the boom joiner fitted to the centre section. Both joiners are fitted to the centre section and will stay there permanently so I have used socket cap heads and nylocs, all stainless steel, bolts cut to minimum length. (The four supplied wing nut bolts will be used to attach the end sections on the hill top). With both joiners fitted, the centre section then is pretty much the same length as the outer sections (by design). I also bought the square boom end caps from Nuxcom to finish them off nicely:
Boom sections ready
The boom was then assembled in my hallway and the centrelines of the element positions scribed on. I used a tape measure masking taped to the boom to ensure it never moved and starting at the 100mm mark on the tape measure to eradicate any errors from the tape measure hook end.

The element clips I needed to find something that was quick to mount the elements and remove them again. The typical single bolt through the centre of the elements I didn’t fancy as it was a bit fiddly especially with cold hands on a windy hill top. My friend found these 10mm pipe clips that were ideal. Snap in and lock, and easy to open again to remove the elements. They will have a finite life but my test piece has had dozens of cycles and they come in a bag of 100 for under £6:
element clipAnother plus point of this is the element centre is a reasonable distance off the mounting surface which means I had good scope for getting the driven element to be on the same plane as the parasitic elements. I just need some suitable plates to mount these on nice and squarely on the boom. My friend offered to injection mould me some rather than my trying to accurately drill out several plates exactly.  So I modelled up a mounting plate to be made from glass fibre reinforced nylon which is extremely strong and stiff for its weight. The image shows the underside. The two ridges are to locate on the square boom:
element mounting plate
Soon in the post came a parcel of element mounting plates. We decided riveting them on was a secure and lightweight fixing method. The two location ridges on the bottom had a slight amount of play when offered to the 20mm boom which of course would be amplified by the approx 100cm elements so I fitted two tiny strips of masking tape which made the plates a perfect fit. Once the rivets were in it doesn’t matter if the masking tape decomposes away:
masking tape slack filler
The small hole in the very centre of the element plate is a sighting hole to align the element in it’s correct position on the boom. This was used to line up to clamp the plate on for the drill of the first rivet hole:
clamped ready to drill
Once the first rivet was fixed, the clamp was no longer needed and the 2nd hole drilled and riveted:
element plate fitted
Then a simple case of fitting the 10mm pipe clips and snapping in the elements in the right place centred on the boom. In order to easily locate the element centrally on the boom with out any time consuming I fitted to each element a piece of adhesive lined heatshrink to be positioned between the clamps. I also added some marking numbers for the 8 parasitic elements, numbered 1 to 8 from from to reflector:
finished parasitic elements
elements numbered
element in numbered location
Now the easy bits are done, time for the driven element. This was the biggest head scratcher on how to make it suitable for repeatedly taking apart and assembling. I needed to come up with a method that both left the electrical connections to the driven element halves but also enabled me to remove them for transportation. This meant a split in each half of the driven, but how to attach it?
I decided to come up with a system of employing a ferrule in the driven to join the two halves. With some custom made parts it would also be mounted on the same element mounting plate as the parasitic elements and is the reason the element plate is larger than a typical one, although that was also good for rigidity and build accuracy.

When I ordered my 10mm element tubing from Nuxcom I also ordered 1 metre of 8mm tubing to do this. But there were two issues with this. The first was this was the only piece of tubing that arrived with a bend in it. If I had planned to use it as an element I would have had to reject it. As it was I could cut out straight parts to use but the 10mm diameter 1mm wall thickness elements have a bore of about 7.92mm and the 8mm tube an outer diameter of about 8.10mm. No chance of a fit. Out with the calculator and it soon transpired 5/16″ should be a perfect size. I bought some T6 grade aluminium from eBay and it was a perfect fit. Sliding with no slop at all.

To cut slits in the 10mm tube to compress it with clamps to grip the ferrules I used two 10mm element clamps to mark a dot each end and each side of the clamp and joined them up to make cut lines to follow:
using clamps to mark centreline
cut lines marked
I’m not fantastic with a hacksaw to be honest but using the element clamps above to hold the tube in the vice I was able to cut (from both sides) fairly neat slits with a junior hacksaw (I wanted thin slits):
element slits cut
Then it was a case of fitting the ferrules into the outer halves of the driven elements and adding a screw to maintain a good mechanical and electrical grip:
ferrules fitted to driven halves
Next to feed that driven element. I decided to straighten out the feed match to take the feed point a little closer to the centre of the yagi. I’m using WF100 75ohm coax which is fairly low loss for its size, and is not too big or heavy. Its claimed velocity factor is 0.85 so I worked out the length as so:

300/144.300 = 2.079m full wavelength
2079/4 = 519.75mm for quarter wave
519.75 x 0.85 = 442mm

DK7ZB gives a length of 440mm for this velocity factor, but I notice all his lengths are in multiples of 5mm so I wondered if he did some rounding down? I hope so!

This is the length of the braid. I hate stripping and cabling up coax so did all I could to avoid twisting bits of braid about. I cut the braid and dielectric off square and about 5mm or so of the outer jacket to reveal the braid. With a very large tipped iron of unknown wattage I was able to tin the braid nicely with no apparent melting of the foam dielectric. I then made a small tinned copper plate to bolt to the N-type socket and solder to the braids making a good earth. For good measure I added a loop of braid from some RG223 soldered all round. Then made the inners as short as I could and soldered to the N-type:
feed point box
To tame the annoying curling coax I found yet another good use for the short boom offcuts I asked Attila to include. I taped the coax out straight to measure the 442mm finished length:
feed match taped out straight
You can see I am using red adhesive lined heatshrink to keep the coaxes tidy and together. In the picture above the tiny box for the driven element connections is threaded on ready for the stripping and fitting of connections. I used a similar method as on the feed end with some copper sheet to join the braids and solder tags to connect to the element halves. This was a very fiddly job but hopefully worth it keeping the connections as short as I could manage:
driven element feed box
To support and space the feed off the boom as recommended by DK7ZB (although this is going to be used for QRP almost exclusively) I got some ABS spacers 3D printed which I placed in position and then wrapped tightly with insulation tape. The idea is to keep the coax off the boom (which it is miles away from) but also as far away as possible from the element plate rivets but also as far from the element the coax passes under:
3D printed coax spacer
The driven element box is supported solely by the driven element inner pieces themselves, but I added a very small 3D printed pillar to make everything secure:
dipole box support peg
Here is the feed match finished:
finished DK7ZB match

As I plan to use this on a lightweight mast section only 20mm in diameter I didn’t think the usual U-bolt clamps would be able to create enough friction to stop the beam spinning on the mast without being so tight to possibly crush or weaken the 20mm ali mast. I bought some plastic 20mm clamps for large yagi elements from Nuxcom to try but they do not have enough friction. So I drew up some half round clamps to be made out of aluminium:
boom to mast clamps

I used a small 3mm aluminium plate in usual manner and bought some 20mm square U-bolts for the 20mm boom itself. As the 20mm boom again is quite small for a long yagi I was again concerned about over tightening the U bolts and creating a weak and potential failure point so I added some small 3mm aluminium plates to allow it to be tightened up nice and tight without any fear of crushing the boom. Here is the finished boom to mast mount. (The two unused holes visible are there to use with the lower 20mm boom mounting holes for a 25mm boom yagi I have):
boom to mast clamp
I used a similar arrangement for the boom support to mast fixings, the aluminium clamps and a slightly smaller aluminium plate. Just a simple M4 bolt per half of the boom support and another plate to help strengthen it all up. The intention is that the boom supports will also help offer a little sideways strength against the wind as well.

To bend up the boom supports I first tried to bend some 20mm square section (same as the boom) in my workbench jaws (seen above in the first picture after cutting the elements). They were not strong enough to bend it! Note this is not a proper vice as such, more of a drilling and cutting bench with jaws. I then thought I might use a bottle jack to apply the force but couldn’t think of anything solid I could jack onto. Then I remembered we have a small 3000lb lever press at work used for punching small holes in sheet metal. I soon made up a jig using a 10 inch square of ¼” steel with some small aluminium blocks and I used the spare offcuts (yet again) to work out the right amount of packers below the centre to give me the bend angle I needed:
20mm square tube bend test
I used 10mm MDF to spread the load from the press and protect the 20mm square tube and a strip of bare FR4 as a bearing and protection to the underside. Once tests were done I quickly and easily put the bends in the actual supports:
boom supports bent up
Checking the bends are matched:
both support strusses parallel
Then just a case of offering them up, drilling holes in the right places and fitting. Finished!
finished DK7ZB yagi

Now for the moment of truth, how does it measure on the antenna analyser? Well to me it looks to be best match at 144.660MHz but is showing SWR of 1.1:1 and 51Ω at 144.300MHz so I’ll take that thanks:
SWR match at 144.150MHz
SWR match at 144.300MHz
SWR match at 144.500MHz
SWR match at 144.660MHz
Here is a real time video showing how long it takes to assemble the elements (I have not shown the boom assembly as nothing unusual or new about the boom assembly):

Finally, here is an assembly drawing:
G1YBB 9 ele DK7ZB assemblyHigh quality PDF version of assembly drawing
Full Bill of Materials PDF

Only job left now is to take this up a mountain top and do some contesting!

Edit: I have done my first contests with this now and it seems to work really well and I got good reports all round. Even with a low loss feeder the radio was not indicating any SWR reading at all on transit. I have come 2nd and 1st in the low power section of the first two UKAC contests I have entered so I am really pleased with the way this yagi performs. It ‘feels’ even as good or better than our 2x 19 element MET yagi array.
DK7ZB yagi in action

GW/SW-006 Fan Gyhirych 20-3-16

Due to construction projects I have had on the go for a while I haven’t been out to do much actual radio lately. But I recently purchased a Baofeng UV-82HP 144/432MHz handheld as I am driving up to the top of two 14,000feet+ SOTA summits in Colorado later in the year and thought it would be rude not to activate them. I got the handheld as the trip is with non radio friends and is for sight seeing so I wanted something small and quick to deploy. So when myself and YL found somewhere new to go for our weekend jaunt up the mountains I quickly checked if it was a SOTA summit and turned out it was, so I grabbed the 82HP and took it! I have not used it as yet so at least I could check it worked!
Baofeng UV-82HP

We parked at the start of the very well defined track leading us most of the way to the summit:
start of the track
The day started cloudy but dry but turned out beautiful later. This picture was actually taken on the way back but is on the early stages of the track. That is Fan Gyhirych on the right in the distance:
Fan Gyhirych in distance

I had 3G coverage on Three network along the track which was handy as I could revise my rather hopeful estimation of arrival time on my SOTA alert! The view whilst updating my alert:
great views today

Once on the summit I was able to spot myself and my call on 145.500MHz was quickly answered. Moving down to 145.475MHz to carry on. First QSO I was a bit weak with the other station but after a call for QRZ when we closed I had a good strong station return. The wind was quite keen on our bare hands, my YL was logging for me as we were stood up. With 4 QSOs in the bag to qualify as an activation my further QRZ calls went unanswered so it was time to move on.

Heading back down the views from the summit ridge were great today:
Cray reservoir from summit
summit ridge view
All in all quite pleased with the little UV-82HP as people could hear me pretty well on its supplied rubber duck antenna. I did have an issue where it seemed to be slow in opening receive after transmit and as a result I often missed first couple letters of a returning call but I found some squelch tail delay settings to turn off which will hopefully correct this.

Only 4 QSOs but enough to qualify.
2016-03-20 log
2016-03-20 squares

Ultralight and ultra strong antenna mast guying ring

When I made my lightweight aluminium portable contest mast I designed up a very lightweight guy ring to use that was both strong and light. I designed it for my friend to injection mould in a fibreglass reinforced plastic that is really strong. The material is so strong I could not damage a 1.5mm thick long credit card size sample by hand even across the edge of a table. All I did was hurt my hands.

So with one eye on weight and one on strength this is the design I came up with. The design criteria was that these rings would hold up a mast carrying a decent sized 144MHz long yagi with at least a 5m boom on an exposed mountain summit in winds at least as strong as the tent will take but also be nice and light and small. They are very similar to many others you will see (there’s only so many ways a guy ring can be designed), but this is only 61.5mm outer diameter and 14.2 grams in weight:
injection moulded guy ring
I went for the simple 4 holes rather than extra holes for 3 point guying that some rings offer as it’s easy enough to just use 3 of the holes. Rope holes are 5.8mm which is plenty big enough for 550lb paracord or other ropes you would use with a lighter weight mast system. The centre hole is 20.5mm sized to fit the top section of my mast. For the lower thicker section it’s easy to open the centre hole with a step drill, in my case 26mm. 30mm is about as big as I would open it too though to retain full strength.

When the rings arrived in the post the first job was to test it for strength. I figured I would make a good test load. Just needed something to hang off and give it some welly. I am a good 170lbs, probably more with boots and big coat on. The rucksack is full of 2 litre bottles of water, probably a good 30lbs more easy. So about 200lbs bouncing weight on the guy ring. This is on a very short length of paracord. A longer length will absorb more shock like a climbing rope does:

Once I was happy with them fitted to the mast and the guy ropes tied on:
bushes and guy rings fitted
And in action:
mast and 144MHz yagi
These rings will also be very useful for SOTA activations where the very ultralight commercially available rings may be a little brittle without adding a noticeable weight penalty. Used for a fishing pole mast the mast will break long before these rings will!

I mentioned that these could be ideal for other radio hams doing SOTA activations and other portable operations wanting a very strong but lightweight guy ring he has made these available (pretty much any quantity) on his website:
https://dura-id.store/product/lightweight-mast-guy-ring

Guying down a lightweight portable antenna mast

Having just finished making a lightweight aluminium portable antenna mast for backpacking VHF contesting I wasn’t really happy with the initial way we were tying down the guy ropes.

Typically I have tied off guys that don’t have tensioners with several half hitches. These are quick and easy but they are hard to tie tensioned properly and I have lost two 19 element MET yagis, a Yaesu rotator and an aluminium scaffold pole when one guy worked loose on a windy day. I didn’t want to use tensioners on this setup as they can work loose and we are going to be operating from a tent and won’t see any loose guys until too late most likely. Also I’m using for this mast lightweight paracord which is meant to be good to 550lbs breaking strain, but I am wrapping that around fairly sharp edged aluminium angle guy stakes which might create a weak point on the paracord. The mast is not massive and I have 2 sets of main load bearing guys but I want this to stay up on exposed windy Welsh mountain tops.

So I thought a round bar would be a better shape to tie the guys to and a clove hitch would be a good start knot as it can be tightened up. For the round bar I thought I would use some of my old climbing karabiners. And to attach those to the guy pegs I would use some small sized climbing rope about 6 or 7mm and use a clove hitch to quickly attach those to the pegs.

Here are the karabiners and rope loops. The rope loops were made from about 1m of rope each and a double fisherman knot used to make the loop:
guying karabiners
Once the karabiner was fitted to the guy peg it was very quick and easy to make a clove hitch and slip it on, tension, then lock off with a couple of half hitches:
guy tied off
guy tied off
This adds an extra 381grams to carry but I think it will be worth it in the long run. I could probably cut that down with newer smaller and more lightweight climbing karabiners (I’m not going to risk the cheapie ebay style mini ones) and probably a smaller rope would be OK to use:
karabiner extra weight
This is one way of many options, I’d love to hear your methods and tip and tricks!
(email explained on welcome page)