Activation of Mt Dandenong, First Summit 2 Summit with Norfolk Island

Hi all,

Surprise activation

I was not planning to do an activation this day (Thursday the 9th of May), but some of the Dx-pedition team of VK9NT announced that they would activate Mt Bates VK9/NO-001, so it was a quick change of plans.

Getting out the vertical

It has been awhile since I have used the vertical on a SOTA activation. Most of the time these days I use the end-fed which works much better for local contacts, but once getting outside of 1000km, the vertical certainly starts to outperform the end-fed. Norfolk island is about 2300 km away, which for a single hop needs a reasonably low angle of radiation, hence the vertical is dusted off.

My vertical arrangement used to consist of 8 75cm aluminium segments above the feed point with guy ropes securing it at the 2nd and 4th segments. I added a loading coil, which improved performance on 40m. It’s tapped, so I also have points for 30m and 80m. I bypass it on anything shorter.

With the squid pole, I dispensed with 6 of the segments and the guy ropes. I attach a wire to the top of the squid pole and attach the other end to the top of the loading coil. The bottom two aluminium segments, plus my feed point (about 30cm off the ground) remain as per the old days. This arrangement takes about 15 minutes to set up 4 radials, which is enough to put me in business. It beats the 45 minutes the old arrangement used to take to set up. If there is any lull in proceedings, I then gradually lay out the remaining 4 radials.

Activating VK3/VC-025

After a short delay, I was on the air about 20 minutes after I was scheduled. I operated from a spot about 70m away from the summit restaurant, which was around 12 vertical metres down. I started off on 40m and worked the usuals. Signal reports were not too bad on the vertical, with many signal reports from 55 to 58 (for those that were sky wave). It’s not as good as the local reports on the end-fed, but certainly the vertical is working well today. I found VK9NT operators, but non SOTA, on 17m working their pile up. They were quite faint, so they were not likely to hear me, certainly amoung all the high power stations from the US calling them.

I saw on sotawatch that the VK9NT SOTA operators were up on 20m. I went over there, but it was a little tough with some QRM. Eventually they changed up 20 and I was able to work them. My QRP signal was weaker than many of the home stations came up on 20m, and it was a little difficult to get in there, with many familiar SOTA chasers working them, plus plenty more from NA and Europe. Quite a number of these were not specific SOTA chasers. They must have wanted the extra calls after working the non-SOTA VK9NT station.

After working VK3CBV/9 for the first ever VK9 summit to summit and VK3QB/9 right with him, I had a little more time. I called on 14.062 CW, just like the old days. Some nice strong 589 station coming in, and I was even getting 559 reports back. Not bad for QRP into W, and sometimes even my received report for QRP is better than what I hear them – which considering my <s1 noise floor is somewhat of an achievement.

Ahhhh for the days of SOTA DX and CW pile ups on 20m. Need to get those Euro and G s2s happening again. There's still an s2s outstanding to Andy MM0FMF.

The vertical at VK3/VC-025

Here’s a look at the setup:

Vertical antenna at Mt Dandenong

Vertical antenna at Mt Dandenong

And a closer look at the feed point, with the LDG tuner handing directly on the feedpoint. There’s an ugly balun on the radio side of the tuner. The 8 radials can clearly be seen in this pic, especially if you click on it.

Vertical antenna feedpoint

Vertical antenna feedpoint

Finally, looking up the squid pole. It’s a much easier configuration using the squid pole to provide most of the physical structure. The only reason I’m still using the aluminium sections is to a) have the feedpoint off the ground, and b) have the loading coil 1.5m above the feedpoint.

Looking up the vertical antenna above the loading coil

Looking up the vertical antenna above the loading coil

All in all, a nice satisfying afternoon.

73, Regards, Wayne VK3WAM

SOTA Activation VK3/VS-016 Mt Gorrin

Hi all,

Another trip to not so sunny Ararat, another activation somewhere nearby. This time, Mt Gorrin. I don’t mind the SOTA rule that only allows activators to claim points only once a year – it acts as an encouragement to activate different hills.

Mt Gorrin is part of the Langi Ghiran and is located in said state park. It is to the south of the main summit with a saddle directly between them. I parked the car on a minor track, which is still ok for 2wd. It is located to the west of Mt Gorrin. There is a walking track that starts off heading north of here, and then swings to the east. This is me on the ascent.

Wayne Merry on the ascent

The track can be followed to a point near the north-norwest of the summit. From here, it is mostly easy going heading southwards. There is another saddle south west of the summit, about 50m vertical height below the top. This can be reached going up the watercourse to the north west of this saddle. Directly north of the summit itself are cliffs.

Here is looking from the summit north to Langi Ghiran, site of my only QRP SSB activation into the EU:

Mt Langi Ghiran

Looking east from the summit towards Mt Buangor and Mt Cole:

East towards Mt Buangor from Mt Gorrin

I operated for nearly 2 hours from a little west from the summit, about 5 metres down. I found a little enclosed on 3 1/2 sides operating location to get out of the quite cold wind. It did not save me from the showers that came from time to time:

Operating location on VK3/VS-016

And here is the trusty antenna, using the Ugly Balun:

Antenna at VK3/VS-016

I have noticed that I can have some difficulty tuning 40m with a very short coax into the ugly balun. Connecting directly or with a longer coax run do not have difficulty. Interesting one.

The activation was during the ILLW weekend, so there were many CQing stations, but high power stations answering their calls. I would rather work SOTA chasers. I worked two local regulars, VK3HRA and VK3PF, and after no further joy, went over to 20m CW, where I worked a further eight unique stations.

All in all, a nice way to spend a Saturday afternoon.

SOTA activations of Mt Matlock VK3/VC-001 and Mt Toorongo Range VK3/VT-026

Hi all,

It’s been three and 1/2 weeks since my last SOTA activation, so it’s time to get out there. Can’t let all the others have the fun.

In the lead up to these activations, I had been keeping a close eye on the weather, and could not but help notice that there had been snow to lower levels. It would seem like my first true on snow activations were on their way. I had also done some work on the antenna setup as described in other posts on this blog.

Mt Matlock VK3/VC-001

First up was Mt Matlock. There is 4WD access to this summit, but I only have a 2WD, so I parked it on the Warburton Woods Point Rd. On the way up from Reefton, I wondered when I’d start to see the snow. There was significant snow from about 1000m. I had parked the car at 1200m altitude, about 1.5km from the summit.

Parking the Prius on the Warburton Woods Point Rd with 10cm snow coverage

It took about 30 or so minutes to climb up to the summit. The summit has a fire tower with a few comms on it, but no mobile phone services. The trig point is nearby, as can be seen in this pic:

Mt Matlock summit with 10cm snow cover

I setup the station to the left of the picture shown above. I was about 100m from the comms tower. I was interested to see if there were any issues with noise from the tower and as it turned out, there were none detected.

The 8 segment vertical was setup as shown below:

My portable vertical antenna at Mt Matlock VK3/VC-001

This was my first opportunity to try the new Ugly Balun and connecting the ATU directly to the feedpoint. In times past, I have used two baluns and about 4m of twin line between the ATU and the feedpoint. I had the twin lead and baluns on hand, just in case. After ensuring that the connections were nice and tight, I used the antenna on 40 and 20. It seemed to work well, including getting some contacts from VK3AFW and VK3PF who were inside 200km. Contacts further out were easy QSOs on 40m. Unfortunatly, there was no DX for me into the US. I wondered about this, but found out after I got home that none of my SMS spots made it on to sotawatch. I could hear plenty of CW at the bottom of 20m, but there was nothing around 14.061 and 2. It seems that most are content to wait for a spot on sotawatch and will not go hunting.

This is a look at the ATU, which is a Z11Pro 2, and the Ugly Balun at the feedpoint:

Antenna feedpoint with Z11ProII and Ugly Balun

Mt Toorongo Range VK3/VT-026

It was time to head off to my second activation. I was able to get the car to about 2km from the summit, which is much better than the 6km that I was expecting. After a walk of about 40 minutes, including about 150m off track, I arrived at the summit. Clearly someone else had been here as there was a rock cairn at the top. It is interesting that this place does not have a proper summit name, even though it is higher by about 10 metres than Mt Toorongo, about 800m to the south west.

There about 5cm of snow coverage here, a little less than Mt Matlock. The weather had also improved, and as can be seen in my two antenna pics, continued to improve as the day went on. It was still only about 1 degree C, but without any wind, it was actually quite pleasant. Before I started, I noticed marks in the snow, which I suspect a wallaby had made:

Suspected wallaby footprints

The vegetation made running all eight radials a little tricky, so I started out with 4, and that is how it stayed. The RD contest had started and this meant that 40m was very crowded. This is where it gets challenging to operate QRP. People either cannot hear you, or do not care that there is a weak station around. They come on frequency and start calling CQ CONTEST. I did not spend a huge amount of time on 40 today. I also found out later that again, I had no spots on sotawatch.

2m was more fruitful. Most contacts here were contest contacts, but it is always interesting to be operating on a mountain in the middle of nowhere and get contacts upwards of 200km away with either a HT 1/4 wave, or my twin lead jim slim for 2m.

As the day wore on, I began to think that it was time for some DX. I put another spot for 20m CW, which did not work, and started calling. I got a contact with KG7E, and he spotted me. Welcome to the pile up! I almost forgot what a SOTA CW pileup can be like. It was good to again put DJ5AV and G4SSH in the log, among others.

The day was drawing late now, and I did not desire to walk back the whole way in the dark, so I packed up around 5pm. A most enjoyable day. If you are reading this and do not know CW, it is not easy to learn, but it is worth it. These SOTA CW pileups are a great deal of fun.

Conditions on 20m HF were quite good today, but I still feel that I am about 2 to 3db ahead on 20m using the ATU and the Ugly Balun than the two 4:1 current baluns and the twin lead. Both setups do not have any evidence of common mode currents and RF at the radio.

I’ll leave you with the two antenna pics showing the improving weather from VK3/VT-026. Regards, Wayne VK3WAM

Antenna at VK3/VT-026

Late sun at VK3/VT-026

Fixing the loading coil and building an Ugly Balun

In my earlier post at: waynemerry.wordpress.com/2012/07/25/improving-the-backpackable-vertical-antenna/ I still had two pending jobs:

  • Fix the crocodile clip on the tapped loading coil
  • Build an ugly balun

Crocodile clip

Clearly they don’t make ’em like they used to. I had not used this clip for very long, but already there were signs of stress, shown below:

Stressed crocodile clip

The top part of the clip is bending and cannot take any force without further yielding. The material is “stooffed”.

A simple job, and also I can fix a problem with the tapping coil being a little too short. I recently purchased some LiPo chargers that came with crocodile clips for their DC power, but I use alternative cables with anderson poles – no clips for my DC power thank you!

The job nearly finished is shown below, with just some electrical tape over the solder joint. Much easier to connect to the bottom of the coil for bypassing, which I need to do on 20 and above. Bonus!

Ugly Balun

The job of an ugly balun is to be a choke to common mode currents. RF is supplied on the centre conductor in coax and the return is on the inner of the coax shield (through the skin effect). There is effectively a third conductor which is the outer of the shield and this is where common mode currents can arise. I have no doubt that they do arise with a coax fed vertical – if I do nothing about them, there is RF at the radio. It interferes with my CW key and it significantly raises the noise floor on receive. This is especially if there is other stuff around nearby, such as a commercial comms tower on the top of a hill or mountain when activating nearby for SOTA. Common mode currents also mean that the coax acts as an antenna rather than a transmission line. This antenna is lying on the ground – not so good.

It is clear that we do not want common mode currents, so we need to get rid of them, and one approach is to use baluns which is what I have been doing, but now I want to put the ATU right on the feedpoint. Solution is an Ugly Balun. This is not really a balun at all, it is merely a current choke.

Designing the ugly balun

In an ugly balun, coax is used to wind around something. This does not affect the inner conductor and the return on the shield. It does expose common mode currents to reactance, and if this is high enough, it will effectively block it. I have read in a number of places that 500ohms of reactance is what is needed to be a good block. Another way to look at this is the reactance should be 10 times more than the resistance of the antenna – presuming the antenna is resonant.

There is a good inductance calculator at: http://hamwaves.com/antennas/inductance.html. I have used this many times and it gives good matches to what is measured using a VNA.

I settled on 21 turns. This gives the following reactance values:

  • 154ohm @ 1.85MHz, which is not very high, but will get rid of the bulk of it
  • 300ohms @ 3.59MHz, which should get rid of around 90% + of it
  • 600ohms @ 7.1MHz, looking good
  • 3000ohms @ 21MHz
  • -11000ohms @ 28MHz. This point is just above coil resonance and it has effectively just turn capacitive – will still block the common mode currents though, so it’s all good.

Building

I used 50mm internal diameter PVC pipe and cut it about 125mm long. I drilled 2 holes at the appropriate spots with a M5 drill bit. After penetrating with the bit, I put it on an angle so I would not excessively bend the LMR195 coax to go through the hole.

Here is what the ugly balun looks like after coiling and threading the coax:

Ugly Balun cable coiled and threaded, but no termination

Next up was to put some connectors on the coax. I use UHF connectors for HF in the field (I also use it for 6m as well). I know that BNC is the QRP standard, but sometimes I’m QRO. I used a male UHF connector on one end to plug into the ATU, and a female connector at the other, for a run of coax to wherever I will operate the radio – keep in mind, this whole setup is for portable activations – typically Summits on the air (SOTA). These connectors I obtained at www.rfsupplier.com/.

UHF connectors for ugly balun, one male and one female

UHF connectors need soldering of the inner conductor, but the shield is crimped. After doing this, the ugly balun is ready for use:

Completed ugly balun

Testing

Now time for testing. The next activation is soon enough, and that will be the real test, but for now I wanted to see what was the insertion loss of this thing. I hooked up to a VNApro in transmission mode:

Ugly balun under testing with VNApro

A screenshot of a test between 1 and 30MHz is shown below:

Ugly Balun test results

Essentially, the insertion loss is around 0.25db from 15m and up, which is close to coil resonance. Lower down, the insertion loss is lower, around 0.19db at 20m, 0.14db at 40m and lower loss on the lower bands. I am happy with this, it is not much higher than the pure loss of the coax itself. It is interesting that there are some loss factors aside from the losses to be expected from LMR195, hence the flat line around 21MHz to 30MHz, which would not happen on a simple coax run. It will be interesting to see how this goes in the field.

Regards,
Wayne VK3WAM

Improving the backpackable vertical antenna

My SOTA activations on HF use a vertical antenna which is all home brew. I decided on using a vertical because:

  • I wanted an antenna that could be used anywhere, whether there were lots of trees or not.
  • It needed to be able to be disassembled into segments no longer than 75cm in length so they could be put into a backpack. Some SOTA summits need significant off-track walking to access, and carrying a large 1m or more item outside the backpack – including being strapped on – was not a great solution for those situations.
  • I wanted something with a low angle of radiation to work SOTA DX. Perhaps this would be at the cost of working local stations, but if the antenna was efficient enough I should still be able to work local, but get the DX as well.

Bunnings sell cyclical al in 10mm, 12mm and 16mm segments – and larger. By using the workshop at my radio club, I have cut these to size.

State of play in June

In June, I had a 6 summit activation long weekend in the Grampians. The final activation was at VK3/VW-007 Near Baroka Lookout. Allen, VK3HRA joined me for the second half of my activation. I was working 20m DX on CW while he worked 40m SSB. Some stations he worked had also worked me earlier on 40m, so I was very interested in his signal reports, which were generally about 2 points higher than mine. It’s not a contest about who has the best antenna, but when conditions are poor, a better antenna could be the difference between a successful activation or not, so it was time to do some work.

Allen was using a Buddistick with one radial. Now some get into the counterpoise vs radial wording thing, but at the end of the day it is about providing some kind of ground to minimise ground losses with a vertical. Now both our antennas were short for 40m, but mine was less short. I also had eight radials! So why the poor performance? His antenna was loaded, mine was unloaded. Answer: Rather than relying on an ATU to match the antenna because because of the short capacitive reactance, I needed a loading coil. Time to make one.

The Loading Coil

I like working multiple bands, and putting a loading coil on the antenna could restrict me to one band, and this would not do. The loading coil needed to be tapped, so I could bypass it, also select tapping points suitable for various bands. With 8 segments, the antenna is 6m long – longer than a 1/4 wave on 20, but short on 30 or lower. I used an online inductance calculator at Hamwaves, designing it on 50mm PVC pipe with a flat piece of aluminium to allow it to be screwed onto the antenna at one of the coupling points. I had already made up a piece of wood about 100mm long with two M8 screws at either end, so this was perfect to mount the coil. The coil would be long enough to have enough turns to resonant the antenna on 80m, as well as making tapping points lower down to resonant the antenna on 30 and 40.

My plan was to put the coil between segments 2 and 3 on the vertical, about 1.5m up from the feedpoint. On the net, and in NEC2 modelling I had done, having the loading coil up as much as possible is better, but it needed to be low enough that I could physically access it to change bands without needing to lower the antenna. I would still use an ATU, but this would be more about matching the resistance, rather than having to deal with all the reactance as well. A short antenna has a feedpoint resistance well below 50 ohms – even 1/4 wave is about 36 ohms, and shorter is lower. As the ground plane is improved, this resistance is lower than otherwise, leading to greater mismatch – but this is good because the missing resistance is missing ground losses. The job of the ATU is to match for this mismatch, but the losses across the ATU would be small.

First use in anger VK3/VC-003 Mt Richie

Now with my new loading coil, it was time to get it into action. Mt Richie was the first activation, with Mt Donna Buang VK3/VC-002 later in the day. Reports on 40m were a good two to three s points up on the usual, with many stations reporting that I had a good signal, rather than the usual “I’m digging you out of the noise”. So it looks like I’m better in the game. I could also tell during the setup that when I tapped the coil on 40m at a suitable tapping point – the radio was hearing a lot more signals. Loading a short antenna certainly seems the go.

One impact of the loading coil was that I could not use the antenna with 8 segments. The loading coil added enough weight that the antenna, despite 2 sets of guy ropes, could not stay up. I had to use the antenna with only 7 segments – 5.25m high from the feedpoint.

The Bunnings 10mm segments were just too weak and I needed something stronger. I had used 16mm segments for something else, but I was not that happy with how ridged it was either. I made up two 16mm steel segments with some 10mm aluminium tubing inside for the M8 threads. The 10mm tubing was held in place by a 6mm nut and bolt about 10cm up from the coupling. This has worked well in my experience, and makes the couplings stronger than other parts of the antenna. This approach would allow me to have a drop in replacement for the bottom 2 75cm segments on the vertical, and should get me back to an 8 segment antenna with the loading coil.

Rubicon forest triple activations

A few weeks after Mt Richie and Mt Donna Buang, I was activating three summits, Mt Bullfight VK3/VN-002, Pyramid Hill VK3/VN-005 and Bill Head VK3/VN-004. Conditions were poor on 40m to say the least, with a large skip zone during the day and attenuation on hops on 40 during the day high. If it was not for the loading coil, I would have not got away with the points from the three summits that day – as described in by blog post. I might not even got a single contact on some of those summits.

By now, I had used the stronger steel segments down the bottom of the vertical, and these had made the antenna structurally sound. There was no buckling anywhere lower on the antenna, which was the reason it used to fall over.

While conditions were poor, and a few days later, Peter VK3PF only got two contacts from VK3/VT-003, underlying the challenge, it made me think that things are still not quite right.

Further improvements

I had always not put the ATU actually on the feedpoint, but somewhere on the ground nearby. This was because the antenna would not be able to bear the weight of the ATU – it does not weigh much, but I was always struggling with the structural integrity of the antenna. My two steel segments seemed to have resolved that problem, so now I have begun to think it is time to put the ATU directly at the feedpoint.

When I first started doing portable activations with this antenna last year, I first had a 10m run of coax from the ATU to the feedpoint, with the radio near the ATU. It is convenient, but performance was terrible. I then had a short, 1m bit of coax from the feedpoint to the ATU, and then a longer run to the radio. This worked better. It does not significantly matter how long the run is from the radio to the ATU. It is all about what is between the ATU and the feedpoint and coax here is bad.

So I built up some homemade twin line from enamelled 1mm wire I had available. The run was 4 metres long. It was this length because another vertical I had been using has a feed point 1.5m off the ground. Even with my 8 segment vertical with a feed point 30cm off the ground, the 4 metres of twin line worked much better than 1 metre of coax. There was nothing wrong with the coax – I could use it quite happily between the radio and the ATU!

Still, the antenna is unbalanced and so is the tuner, and twin line is a balanced transmission line, so running an unbalanced signal down it must not be good. I built two Guntella 1:4 baluns, one to go at the tuner, and the other at the feedpoint. This further improved things – there was evidence before of RF at the radio, and these baluns removed it, also my RX was much better – further evidence of common mode currents before. One time I forgot a balun, and using the setup without them was certainly worse than what I was used to.

Reading W2FMI Jerry Sevick’s Transmission Line Transformers made me think that I still have not got this thing quite right. The Loading Coil gets rid of capacitive reactance, but it can not be said that there is 50 ohms on one side of the balun and 200 ohms on the other. This would mean that the losses of 0.05db that I had measured using a network analyser on these baluns would not be the case because of these mismatches. Over the Gippstech weekend, I did some Keith Roget activations at 100 watts in Morwell National Park and Tarra-Bulga National Park. The baluns got warm. Not hot, but the hotter one had it’s temperature raised about 20 degrees. This tells me that the loss is much greater than 0.05db, more like about 2 to 3db. There are two of these baluns, so there is 4 to 6db of signal improvement waiting to be taken.

So my current plan of attack is to do the following:

  • Put the ATU directly on the feedpoint of the antenna, now that the steel segments have removed the instability problems. Get rid of the twin line and the two baluns. The ATU is unbalanced, feeding an unbalanced antenna.
  • There will be some common mode currents reintroduced because the baluns are gone, and we do not want these. We certainly do not want them anywhere near the radio, but across the ATU is not such a big deal. So a 10 turn on 50mm PVC pipe Ugly Balun with coax – which is really a 1:1 unun will do the trick.

This Ugly Balun will get rid of the common mode currents that run on the outside of the shield, but because it is made of coax, the inner conductor and the inner surface of the shield are unaffected. There will be enough reactance on the Ugly Balun to block common mode currents even at 80m, but not too many turns to not work at 10m. Being on the radio side of the ATU – but right next to the ATU, means that the RF inside is going along a matched transmission line with low SWR, so the loss of this Ugly Balun should be very low.

That’s the plan, we’ll see how it goes at the next activation.

Regards, Wayne VK3WAM