(As is my usual, this article has a bunch of links – click on as many as you wish to receive the full experience)
by Vince (VE6LK)
In May of 2023 I embarked on a two week vacation to Hamilton Ontario that co-incidentally happened to include a side trip to Hamvention just outside of Dayton, Ohio.
For a guy living in Alberta, Canada, this would prove to be quite the trip and it created memories to last a lifetime. I also was told that I could play radio during the trip provided my wife would get to see some of the many waterfalls in the City of Hamilton, the area we’d call home for our two week trip.
And thus the planning began. I started overlaying POTA entities that overlapped on waterfalls so we both could visit and enjoy in our own way. It also meant I had to figure out what radio gear and, most importantly antennas, to bring along.
I landed up mostly running with low-slung antennas. By this I mean something between 4 and 10′ off the ground and horizontal in orientation. But it’s what I discovered about this simple approach that made it appear like pure magic to me – I made great contacts at what I would consider to be beyond NVIS distances including one from OH to UT!
And as I am an opportunist, I made this decision at 23:25’ish z and I had not yet arrived at the park but the target was only a few minutes away! I would have until 23:59:59z to complete it if I were to be successful. “It’s time to break out the Elecraft AX1 antenna I bought at Hamvention last week“ I think to myself. It would be my first time using the antenna. I had pre-read the instructions and knew what had to be done in order to set it up.
The whole thing would unfold like a Formula 1 pit stop, albeit a wee bit slower <grin>.
On Thursday, April 27, 2023, it was pouring rain, so the perfect time for a little POTA, right–?
Actually, I had an idea: in the past, I’ve been known to play POTA under the roof of a picnic shelter on rainy days. I’ve even been known to use my AX1 antenna inside the shelter, under a metal roof. Quite a few times, actually.
An in-the-shelter activation was also the perfect opportunity to test the new Chelegance tripod that fits both the MC-750 and the JPC-12.
A number of readers have reached out asking about this tripod, so when Jesse at Chelegance asked if I’d like to test it, I agreed to do so.
To be clear, he sent this to me at no cost for evaluation. It’s actually quite affordable ($30 on the Chelegance website, $40 at DX Engineering, for example) so purchasing it would have been easy enough, but Jesse also wanted me to evaluate their new FT-818 ATU, so he sent both at the same time (you’ll see the ATU in a future field report).
The tripod feels very sturdy and is simple to deploy. It’s also a little heavy, so keep that in mind if you plan to pack it in for a long SOTA hike.
A number of you have purchased this tripod and have only had positive comments. I now see why.
I speak about this in more detail in the activation video below.
Lake Norman State Park (K-2740)
I decided that it had been too long since I had activated Lake Norman State Park, so I hopped in the car and headed to Troutman, NC! Lake Norman has a number of picnic shelters and covered areas thus a very safe bet.
It was a rainy day so, of course, I pulled into the Lake Norman picnic area only to find one other car there. In fact, by the time I had taken my backpack to the picnic shelter, that other park visitor appeared at a trailhead, hopped in her car, and left.
(As is my usual, this article is full of hyperlinks – click on as many as you wish)
The days leading up to my first Hamvention trip were a bit scattered to say the least. While I was pretty sure I remembered everything and even documented most of my gear on Twitter, I would only discover that the bag I intended to carry my gear around in was too small once I arrived in VE3-land. The very next morning I was shopping in several big box stores trying to find the perfect bag only, hours later, to discover an Army Surplus Store across the street from my activation and after the activation concluded.
Anyways, the short summary on the shopping trip was that I figured out a way to get me through the trip without spending a fortune.
The day’s goals were to make a simple activation at a park near the family where we were visiting east of Toronto. Before travelling I scoped out POTA entities that were nearby and had not yet received a CW Activation thus putting me closer to my CW goal for the year.
I landed up at Lakefront West Park VE-1480 in Oshawa Ontario. A recreational trail winds along the waterfront of Lake Ontario about 100m away, and eight baseball diamonds are the central feature here. Given the lack of trees at the park, and that I do not have a small mast on this trip for my EFHW -although I may remedy that at Hamvention- I chose to deploy my Comet HFJ-350M with some simple ground radials. With the solar reports showing SFI 149, SSN 134, A 19 and K 2, I chose 20m as the band for the day. 5W on my KX3 into a ground mounted vertical with one each 66′ and 33′ radial wires would have to be enough.
I have the full Comet HFJ-350M kit including the bag to carry all the pieces in. I also have a ground stake from eBay that comes with a 90 degree SO-239 adapter allowing me to attach feedline on the side and the antenna on the top. Not including the ground radials, the whole kit rolls up reasonably small, about 3″ in diameter and 12″ long. Continue reading Lakefront QRP and Bags Galore!→
Do you usually try to use an isolator or do you often let your wires touch branches by just pulling them over? When you deploy 20m EFHWs, for example, do you try to avoid having an end touch a branch and only have the throw line going over the branch? I tried to go through your videos and look but you don’t often mention how far you pull the wire up and possibly over. Thanks!
This is a great question!
Before I answer, I’d like to add a little context:
I am a QRP operator. The maximum amount of power I use in the field is 10 watts, but 99.5% of the time, it’s actually 5 watts or even much less.
I am answering this as a field operator, meaning I’ll be referring to temporaryantenna deployments.
That said, the quick answer is no, during park and summit activations, I do not worry about my antenna radiator wire touching tree branches.
I do isolate the end of my wire antennas from tree branches and leaves, but I don’t worry about other parts of the radiator touching.
Also, all of my antenna wire has some sort of jacket–I don’t run bare wire in the field.
Many thanks to Dale (N3HXZ) who shares the following guest post:
Does your antenna counterpoise orientation matter?
by Dale (N3HXZ)
I am an avid SOTA and POTA activator and love field operation. I use a portable vertical whip antenna with a single counterpoise for my antenna system and have always wondered if orienting my counterpoise would provide some signal strength gain in a particular direction. I decided to run a series of tests using WSPR to gather field data, and use statistics to answer the question:
Does one counterpoise orientation favor another in terms of average signal strength?
WSPR is a great tool for antenna testing. You can study various antenna configurations by making some WSPR transmissions and then checking the data on the WSPRnet database to see how well the signal was received at various stations located all over the world. You have to be careful in interpreting WSPR data though as receiving stations have different antenna and radio configurations, and the band propagation can vary rapidly at times. So how do you take advantage of all the data you receive from stations and draw some meaningful conclusions? I have found that using proven statistical theory in analyzing the transmitted signal strength received from individual stations can provide you results that you can confidently trust.
So what statistical algorithm is helpful?
For antenna signal strength comparison between two configurations, you can use an independent two-sample t-test with a one-tailed t-test evaluation. It sounds like a mouth-full, but it is quite simple. For our purposes, the t-test compares the average signal strength at a given receiving station from two different antenna configurations. The one-tailed test validates or invalidates the hypothesis that one antenna configuration produces an average signal strength greater or less than the other antenna configuration.
The testing requires that you run WSPR long enough to gather multiple reports at a single receiving station for both antenna configurations. Using the signal strength reports, you compute the average signal strength and the standard deviation of the signal strength over the sampled data points. Excel can easily provide that data. With this information and the number of sample points for each antenna configuration (they can be different), you then run a calculation by hand or in Excel to compute the ‘t’ value.
This ‘t’ value is then compared to a critical value for the number of sampling points from a ‘Students t table”. If the ‘t’ value is less than the critical value you can confidently conclude that the hypothesis is false and therefore conclude that there is no significant difference in the mean value of the signal strengths between the two. If the ‘t’ value is greater than the critical value you can accept the hypotheses that one antenna configuration produces a greater or less average signal strength than the other configuration. Continue reading Dale uses WSPR to test counterpoise orientation→
Mini Field Report: Testing the Gabil 7350T and BaMaTech TP-III on a brisk SOTA activation!
by Steve (MW0SAW)
Went for an early walk/SOTA activation up Fan Fawr GW/SW-005 (734m) this morning (9/4/23). I think someone said it was supposed to be the hottest day of the year in the UK. It was about 5 deg celsius with a bitter wind chill of -2c on the summit! It’s very close to the highest peak in South Wales, Pen Y Fan (886m).
As I mentioned a couple of weeks ago in our emails, I wanted to test a new compact antenna I purchased recently, called the Gabil 7350T in the USA, and branded as the Sharman MD-3500 in the UK where I got mine. I also took the Gabil GRA-ULT01 MK2 tripod which I did purchase from the USA on Amazon.com.
Another first for the the activation was the Bamatech TP-III ultra compact paddle, Dinos were included 🙂
Starting my walk, the lovely view of the reservoir quickly disappeared and was the last view I would see ascending into the mist.
I took refuge in my Decathlon 1 man camping shelter, setting up the tripod and antenna close by.
The wind was howling and turning my back the antenna toppled over. This was quickly resolved with a tent peg on one of the tripod legs. Quick setting of the slider with the analyser got 1.2 SWR and so after a slurp of coffee, I started to call CQ on 20m CW. A nice stream of European qsos ensued with good reports (many 599), it was pleasing to hear with such a small antenna (about 8 ft). Just as the contacts were drying up, I was taken aback by a strong VK station! Always great feeling to get some dx like that but especially pleasing with this tiny antenna on its maiden voyage 🙂
I switched to 20m SSB for a few more QSOs but struggled with QRM on two frequencies. My allotted time was running low and my fingers were numb, so I packed up the HF and got the handie out to catch a few local VHF contacts.
So what can I summarise from this activation, well I can safely say I love the Gabil/Sharman antenna and Gabil tripod. They would make a really nice additional to a small go bag, they seemed to work almost as good as a full size 1/4 on 20m. Time was limited this trip and I was too cold to hang about to try more bands, but extremely pleased with the performance so far.
The Bamatech key is a pure work of art, beautifully made, sensitive and precise. Probably my best portable key to date in my collection.
(Note: Amazon links are QRPer.com affiliate links.)
Thomas, thanks for all of your activation videos related to the Elecraft AX1 antenna. I ordered one the day you announced the package deal, and it arrived in less than a week. I’ve activated a few parks with it already (20m SSB). Like you and many others, I’m impressed.
About a year ago, a friend (NG4S) loaned me his pair of WSPR transmitters and suggested that I explore building and comparing antennas. I’ve been hooked on antennas of all kinds and WSPR since then.
I began doing WSPR tests on the AX1 the day after it arrived. With two transmitters set to the same frequency and power output, you can do direct comparisons between two antennas under identical propagation conditions.
I’ve already done a couple of comparisons between the AX1 and other commercial antennas. But I think the test I just completed might be of particular interest because it pits the AX1 against an antenna I’ve seen you use many times – a 28.5’ end fed with a 28.5’ counterpoise. I used 24 AWG silicone insulated wire. The end of the radiator was placed on a 19’5” telescoping fishing pole. This is my preferred POTA mast when I can’t use a tall tree.
I spent some time trying to control other variables so that the only significant difference during the test would be the antennas themselves.
For example, the SOTA Beam WSPRLite Classic transmitters don’t have an ATU. So, I had to make the antennas resonant on the 20-meter WSPR frequency of 14.097 MHz. For the AX1, Thomas’ videos helped a lot. I used a clip-on capacitance hat and adjusted the counterpoise to 15’ 2”. This gave me an SWR of 1.17:1. For the end fed, I tried the two UNUN’s I had available and settled on the 49:1, which got me the closest (2.2:1). I then used a manual tuner to achieve an SWR of 1.29:1.
I also wanted to deal with the difference in power output between the two transmitters. Although they’re identical, and both set to 20 milliwatts, there is no way to ensure both are actually producing that output level. Based on tests by NG4S, one of the transmitters runs at 19 milliwatts. The other actually outputs 27 milliwatts. So, my plan was to run the test for 48 hours. At the end of 24 hours, I would switch the transmitters (and callsigns) so that both antennas would benefit (relatively equally) from one of the transmitters being stronger.
At the end of Day 1, I reviewed the data from the two transmitters on dxplorer.net/wspr. The end fed averaged a 5.7 dB gain over the AX1 based on reports from receiving stations that spotted both transmitters in the same 10-minute block (simultaneous spots).
On Day 1, the stronger transmitter was on the end fed. The maps below are from WSPR.rocks.
As I mentioned in my recent AX1 vs AX2 video and blog post, I purchased an Elecraft AX2 antenna and bi-pod in late January (note: two days before Elecraft announced their February ’23 sale price! Doh!).
I received the AX2 package a few days later and I was certainly eager to take it to the field.
My first opportunity came on Tuesday, February 14, 2023, when a short activation window opened up in the afternoon.
Zebulon B. Vance Birthplace (K-6856)
One of the first things I noticed after taking the AX2 out of the package is just how solid and compact it is. The AX1 is short, but the AX2 is a few inches shorter because the base is more compact.
Unlike the AX1, the AX2 is a mono band antenna, thus the coil only needs to accommodate one band. When you receive a new AX2, it’s configured for 20 meters out of the box, but the user can modify the coil to work anything from 20 to 6 meters.
Even though I mentioned this in my AX1 v AX2 article and video, I’d like to reiterate that the AX2 is nearly-resonant on 20 meters. It is not reliably resonant.
I’ve still been receiving a lot of messages from readers stating that their AX2 and AX1 are resonant on 20 meters, so they don’t pack any sort of matching device in their field kit. They simply hook the AX2 up to their little QRP radio and hop on the air.
While it’s true that these antennas may provide an acceptable SWR most of the time, you really can’t rely on a solid, reliable match as you could with an end-fed half-wave.
I’ll repeat what I mention in a previous post:
Small verticals like the AX1 and AX2, that use coils to electrically “lengthen” the antenna, have a higher Q than, say, a large aperture quarter or half wave antenna. In practical terms, this means that the window of resonance is narrow and more fickle than, for example, an end-fed half-wave.
A lot of factors can affect the SWR on higher-Q antennas like the AX1/AX2 including:
the type of terrain,
height off the ground,
length of counterpoise,
configuration of counterpoise,
and, most notably, the operator’s own body capacitance.
You may find that the AX2, for example, is natively resonant on 20 meters at one location, but isn’t at another location. This is quite normal. It’s also the reason why Elecraft states that both antennas are designed to be used with an ATU.
So there you go! If I hook up my AX1 or AX2 to a radio, I’ll always have some means of matching the impedance–either an external ATU, or a capacity hat. You can also tinker with the length of the telescoping whip and counterpoise to tweak the match.
How I found the best antenna for my SOTA/POTA activations
by Thomas (DM1TBE)
Until January this year I had a German “Klasse E” / CEPT-novice amateur radio license (equivalent to the US General Class), which limits the use of HF to the 10-,15-, 80- and 160-meter bands. When I started with SOTA I used homemade single band end-fed antennas most of the time. However, that is only feasible for the 10- and 15-meter bands.
Unfortunately, both bands are very moody and sometimes they have not worked at all. Unlike the UK for example, FM is uncommon for SOTA in my home association DM (i.e. Germany Low Mountains). You can be lucky and get your 4 QSOs, but I did not want to rely on pure luck.
Therefore, I bought an end-fed half-wave antenna for 10-, 15-, 20-, 40- and 80-meter bands, after some experiments with 10-80-meter end-fed half-wave antennas, from a small German company called ANjo.
Although I could not use the 20- and 40- meter bands at that time, the EFW80-10P (en: auto-translated) antenna gave me the possibility to use the 80-meter band. The antenna could also be tuned for 15. It has a mechanical length of 23.6 m / 77 ft and a coil for the 80-meter band. It is pretty lightweight with 0.4 kg / 14 oz and allows up to 30 watts PEP – more than enough for me. 80-meters is not the best band for daytime SOTA activations, but in 21 months doing SOTA activations, it worked 37 times and tipped the scales for an activation from time to time.
It was sometimes a bit tricky to raise the long wire into the air, but it always worked … better or worse …somehow … like here in the woods along a trail.