(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.
Holey Moley lookit all the molle and backpacks!Thomas’ reaction upon seeing this photo was predictable 😉
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.
DX Toolbox on iOS – click for App Store link
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→
Many thanks to Steve (MW0SAW) who shares the following field report:
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.
The Gabil 7350T Compact Antenna and Gabil GRA-ULT01 MK2 tripod
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.
Equipment:
(Note: Amazon links are QRPer.com affiliate links.)
Many thanks to Keith (KY4KK) who shares the following report:
Extreme QRP – Testing the AX1 with WSPR and 20mW
by Keith (KY4KK)
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.
“Resonant-ish”
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)
Intro
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.
In January this year, I upgraded my license and a new world of HF-bands opened for me. Although I have learned a lot about propagation for the exam, I am in favour of a German saying: “The difference between theory and praxis is larger in the praxis than in the theory”. Continue reading How I found the best antenna for my SOTA/POTA activations→
Many thanks to Terry (N7TB) who sent the following question by email and has kindly agreed to allow me to share it here along with my response on QRPer:
Hi Thomas,
I cannot tell you how much I appreciate your POTA videos and all the suggestions you have made that I have adopted. I look forward to every activation you put on video. […]
[…]I have a question for you about using your AX1, and would really like your advice. I marvel at how quickly you can activate a park even with an AX1 antenna on 5 watts. I also have an AX1 antenna, counterpoise and KX2[…].
Anyway, I was out today activating K-0213, Maude Williamson State Park, about 20 minutes from my QTH in West Salem, OR. I operated 12W into a 33ft. EFHW antenna suspended vertically from a 31 ft. Jackite mast. All my activations are CW; I usually activate 20 meters.[…]
I was able to finally work 22 stations in an hour and a half, mostly in CA, UT, MT, and one in AZ. I did get a contact in KY, AZ NM, and MB, but it was a tough go for them to hear me. Most of my activations take me a bit over an hour to get 20 contacts.
As I thought about how much easier it seems that you are able to activate, I started to think about geography and population density differences between the East and West coasts. I used Google Earth and measured almost all points east of the Mississippi from Asheville and most were within 1200 miles. I would guess 2/3 of the US population live in this area. I drew the same range from my QTH and I get about half way into MT, barely into WY, most but not all UT, just touch the NW corner of AZ, and all of CA. In all but CA, I would guess the population total in this vast area is less than Illinois. That is my dilemma. I would love to be able to go out, setup my AX1 with my KX2 on even 10 watts, and make quick activations, but I would be surprised if I would get many contacts because the distances are so vast in the West and population density so low. I will actually try using the AX1 when the WX gets better and I can sit at a picnic table. So far, I have had little success with it, even deployed with the correct counterpoise. Do you have any thoughts on how to be successful with the AX1 from the West coast for POTA, or should I just concentrate on other antennas?
[…]Thanks again, Thomas, for the emails you have sent me with suggestions about equipment, and for all your great videos.
Very 73,
Terry
N7TB
Hi, Terry,
First of all, thank you so much for the kind words. I really appreciate that!
Regarding your message:
Keep in mind that the day you were operating was a very strange day in terms of propagation. There were times when we were having radio blackouts (especially in the western half of the US) and there were times propagation was amazing, yet very unstable. We were hit by so many heavy CMEs this weekend–one seemingly on top of another.
I think you do have a valid point, though, about the geography–one I try to mention when talking about compromised antennas like the AX1.
QSO Map from my latest AX1 activation.
I realize that I enjoy a lot of success with the AX1 because of where I live. I guarantee that the bulk of the US ham radio population is within easy reach of my AX1 antenna, no matter what band.
For you? There are no hams to your west (within easy reach), extremely few to your north (save WA and BC), and the best ham density is to your south in California.
In your shoes, here’s how/when I’d try using the AX1 (keeping in mind I’ve never operated POTA in the western states):
First, I would focus on using 40 meters when the band is healthy and/or for early morning, late afternoon/evening sessions. That should snag contacts across WA, OR, and CA with the AX1. Might be a stretch for southern CA, but I think you could make that work. The only caveat is that flaring has been wiping out daytime 40 meters a lot lately. You might check band conditions in advance.
I would also consider spending time on 17 meters, and possibly 15 meters with your AX1. This might throw your signal across to the midwest, Ohio Valley, and beyond. 17 and 15 meters isn’t typically as productive as 20 meters (at least, for me) but I routinely log west coast stations on 17 meters with the AX1. 15 meters is also getting a lot of attention in the POTA spots!
A wire antenna is almost always a better option than the AX1 if you have the time and space to put it up, but the AX1 is just so darn convenient.
Cheers, Thomas K4SWL
More suggestions?
The reason I asked Terry for permission to post his question and my reply here on the blog is because I suspect there are west-coasters (and those in similar geographic situations) who may be able to share some helpful strategies.
There are so many factors involved beyond what I mentioned in my reply. In fact, I imagine if the goal is to work parts further east, then adjusting the activation schedule for Central and Eastern time zones might also help (for example, not activating during dinner hours when I always see a bit of a lull in hunter activity).
If you have some experience, please feel free to comment!
As I mentioned in previous posts, I’ve been using the Elecraft AX1 in heavy rotation this year. I made a commitment to myself to do a string of activations with it in January and February and also pair it with a wide variety of radios beyond the Elecraft KX2 and KX3. So far, I’ve paired the AX1 with the:
In truth, the AX1 can be paired with any radio when you use a tripod mount.
It’s a bit trickier when connecting the AX1 directly to a radio and using the Bipod as a support because 1.) the antenna connector on the radio mustn’t be too high off of the surface, 2.) there needs to be enough clearance on the back of the radio to accommodate the bipod legs and 3.) ideally, it’s nice to have a ground point on the radio, else you’ll need to clamp the counterpoise to the shield of the BNC connector.
In addition, if your radio doesn’t have a built-in ATU of some sort, then you’ll also need a capacity hat or external ATU to finish off the impedance match. (For more notes about the AX1 and AX2, check out this previous post.)
Of course, you don’t have to use Elecraft’s bipod to support the AX1 when directly connected to a radio–you can build or 3D print your own support–but the bipod is really convenient when it does work.
Objective: Lunch Box Radio
One radio I’ve been eager to pair with the AX1 is the Penntek TR-45L.
Many thanks to Skip (K4EAK) who shares the following guest post:
The QRPguys DS-1 Portable Antenna Kit
by Skip (K4EAK)
There have been several videos and extended comments lately about the Elecraft AX1 and AX2 antennas, both of which function remarkably well for a small, highly compromised antenna.
For those interested in other, similar designs, especially those hams who find that building the equipment is half the fun, another option to consider is the QRPguys DS-1 antenna.
The DS-1 is similar in concept and design to the AX2. It consists of a base-loading coil, a 46.5-inch collapsible whip, and a plate to attach the antenna to a small tripod. One can also purchase an add-on 40-meter coil. The can be deployed in just a couple minutes and, when collapsed, the longest portion is only 6.5” long, easily fitting in the palm of one’s hand. QRPguys recommends a 16.5′ counterpoise; I use two such wires, usually spread out at a 180-degree angle. I’ve also used it with a clamp-on mount and a car window mount.
Building the antenna is simple and took me less than an hour. After installing a BNC connector into a brass plug and inserting the plug onto a length of PEX tubing, one simply runs the supplied 22AWG wire from inside the tubing, out and around making 22 turns, and then sealing it with a length of heat shrink tubing.
There are really only two aspects of assembly that are slightly more difficult. The first is that it’s necessary to drill and tap two holes for 4-40 screws, which obviously means that (1) one needs a 4-40 tap and (2) one needs to be careful tapping the threads to assure a clean cut. The second is that the heat shrink tubing, at least as supplied in my kit, was grossly oversized, which required some finesse in getting a final product that was at least reasonably aesthetic, to say nothing of accomplishing that without dry roasting my fingertips.
Field testing of the DS-1 shows that it works surprisingly well. The SWR is well below 2.0 across almost all of the 20-meter band and where it is higher than that (the upper end of the voice portion), the KX2 internal tuner can tune it easily. As one would expect, on 40 meters the antenna has a somewhat narrower range, although the KX2 tuner has handled it on all of the frequencies I’ve tested so far (all CW). And it appears to be efficient enough.
I have used it on numerous activations and consistently get to the requisite 10 contacts within 20 minutes or so after getting spotted. After that, the number of contacts depends on the time available, but for those occasions when I have only a 30-minute window for an activation, the antenna is a convenient and practical alternative.
I keep the antenna, the tabletop tripod, and the counterpoise wires in the water bottle pocket of my pack, ready for use whenever I have a few moments for a quick activation.
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