Preamble: Based on some social media comments, let me say at the outset that: a) I know that the ATU does not tune the antenna, but provides a good match to it; b) resonant antennas are more efficient; c) that you can tune a dummy load; d) just because you can tune something doesn’t make it an effective radiator. I do know these things. This post is intended as a bit of fun and to see just how much of a mis-match this ATU can handle to press objects into service as an antenna, even a very inefficient one. Please don’t take it too seriously!
Ask any Xiegu owner of the X5105, G90 or the XPA125B linear amp, and they will all tell you that they have great auto-tuners. Well, I own a X5105 and recently was lent a G90 for review for Practical Wireless. I decided to put the ATUs to the test using my X5105.
But what challenge to give it? Well, how about trying very, very long and very, very short antennas? What about metal gates, a cow shed roof, the framework of a polytunnel and a stock trailer?
I love G4USI’s philosophy with this fun experiment: see if it’ll match, then see if you can get spotted!
Xiegu ATUs certainly have a wide matching range–so do the Elecraft KX series ATUs. Indeed, having a super capable trans match means that you don’t necessarily need an extra inline transformer to make matching a non-resonant wire easier.
And I see why G4USI mentions that there’s a difference between a good SWR and efficiency. It’s an important note because, yes, dummy loads will yield perfect SWRs!
Many, many moons ago, I used to participate in a fun contest where the idea was to make as many contacts as possible from not-so-standard antennas. The rules of the contest really pushed the operator to metal objects that, in no way, resembled an antenna. They didn’t allow electric fences or even gutters, if I recall correctly.
One year, I remember loading two identical small trampolines and my in-law’s house. I think I ran them QRP with my Elecraft K2 and used a ZM-2 manual tuner to match them. I’m sure they weren’t efficient, but it worked! I made several contacts with other contest stations and it was amazing fun!
Have you ever had success with a non-traditional antenna? Please comment!
I don’t know about you, but part of the fun of playing radio in the field are the inevitable frustrations.
It might not feel like it in the moment, but when I eventually overcome the challenges of a mistake, I feel like I’ve truly accomplished something.
That was my little epiphany this morning: making mistakes has perhaps made me a better radio operator. Less-than-efficient field deployments have honed my skills and had a major influence on the gear I pack.
If you’ve read some of my (rather rambling) field reports in the past, you’ll note that I rarely do field activations with the exact same gear combinations each time. I feel fortunate enough that I can pair different radios with different antennas and different accessories. I get a small thrill out of not knowing exactly how well a combination will work, especially if I’m not activating a rare all-time new park or tough summit for that matter. In cases where getting to the site is a challenge in and of itself, I want to use a trusted combo of gear.
It’s that wee bit of mystery that attracts me to the field.
If I approached POTA more like a contest–where activation and contact numbers were my focus–I would have installed a mobile HF rig in my car a long time ago. I could rack up way more parks and contacts that way. It especially simplifies multi-site activation days since it effectively eliminates the time involved in setting up and later packing up gear. Mobile operating is the most efficient way to hit number goals: drive up to a site, start calling CQ, work your stations, then move on.
K-6937 & K-4510
(Photo credit: K4TLI)
Yesterday, I did a last minute “two-fer” activation of Pisgah National Forest and Pisgah Game Land. I had not planned to do an activation that day–temps never rose above 29F (-2C) at the QTH day and it also snowed and flurried all day long. Winds were very gusty as well, so it effectively felt much colder on the skin.
I wanted to hike up to the ridge line behind my QTH and do the activation but I knew up there temps would be lower and (worse) winds much stronger. Cold doesn’t really bother me, but strong winds do. This was also the first weekend my ankle felt almost normal after twisting it badly last month. It’s healing and I hope will be in shape for a long hike from my QTH to a six point SOTA summit next weekend with my daughter (K4TLI).
All of those factors combined pointed toward simply staying at home, drinking coffee, and reading a book.
Hazel was ready for some field radio fun, though. (Photo credit: K4TLI)
But I really wanted some outdoor time. And I really wanted to make an activation with my Elecraft KX1, so I decided that instead of hiking up in elevation 800 feet, I’d drive down about 900-1,000 feet to a forest trailhead. That would get me on the air in a protected valley with less wind, less snow, possibly warmer temps, and much less hiking which would be easier on my ankle.
The Last-Minute Antenna
When I use the KX1 in the field, I typically pack a very simple antenna: one length of radiator wire and one length of counterpoise wire–connected to a BNC binding post adapter, I let the built-in ATU sort out the match.
When I owned my first KX1, I had a magic length of radiator wire (the length of which I can no longer remember) that seemed to work amazingly well on 40, 30, and 20 meters.
My new-to-me KX1 came with two lengths of wire: one 23′ and one about 20′. Although I made a fun and successful activation with this setup, the radiator was simply too short for the KX1 to find a decent match on 40M.
On the way out the door, I decided to cut a new radiator and counterpoise out of scrap wire I use for antenna experiments.
Being a bit stubborn and also in a hurry to beat sunset, I did no Internet research to sort out the ideal lengths for 40 meters. I simply cut a 17′ length for the counterpoise and about 27.5′ for the radiator.
In the Field
After arriving on site, I deployed the antenna and tried finding a match on 40 meters with the KX1’s internal ATU.
No go.
I tried a few times hoping maybe the ATU would find something even semi-reasonable in terms of a match, but there simply wasn’t enough radiator to make it work. That was a shame because forty meters would have been the ideal band for yielding quick contacts this time of the afternoon.
I had options, but I wanted to make what I had work.
The activation took time and patience. The 30 meter band was now my best bet and it’s where I logged all ten contacts for a valid activation. I tried 20 meters where I had a 1:1 match, but the band was dead.
At one point, I switched out the KX1 with my KX2 that I also packed. I tried to find a 40 meter match with the superior KX2 ATU, but physics got in the way again. 🙂
40 meters was an option
Let’s be clear here: I could have easily cut 4′ off of the counterpoise and attached it to the radiator and I bet I would have gotten a match on 40M. Since the counterpoise was lying on the ground, its length was less crucial.
The EFT Trail-Friendly end fed antenna was also in my pack.
I also had a perfectly capable 40/20/10 en-fed antenna in my pack. Switching out the antenna would have only taken four minutes.
I bet I could have easily yielded 20 additional contacts on 40 meters because the band was in great shape. Almost without fail, 40 meters is my most productive band.
Working with limitations
Thing is, I’m starting to understand that I like working with self-imposed limitations.
Perhaps this is why I love QRP and low-power radio so much: I get a little thrill out of doing more with less.
Yesterday, even after I realized it would be a struggle to log my final three contacts on 30 meters, I persisted. One motivation was I’ve never completed a full activation using only 30 meters. With a little patience, I knew I could snag my ten contacts.
The only things making it a challenge were the facts that temps were dropping rapidly, winds were picking up, and the sun was setting. Hazel (the POTA dog) who so eagerly jumped in the car when she saw me put on my hiking boots earlier, was also starting to shiver.
Fortunately, after trying another short stint on 20 meters, I returned to 30 and worked two more stations in quick succession giving me a total of nine contacts.
It started to get darker, so I hunted and found an operator calling CQ on 30 and simply made contact with him. He wasn’t a POTA station, just a general CQ call. He kindly gave me his details for the logs.
Lessons learned
I made a video of most of this activation and will upload it when I have a little bandwidth to do so. I’ll embed it in a shorter field report here on QRPer since I’ve described so much already.
Even though it was a challenge making ten contacts to accomplish a valid field activation with my time constraints, I’ll admit that I really enjoyed the challenge.
Next time I head to the field with the KX1, I’ll actually test the antenna prior to leaving the QTH.
In fact, I’m planning to make two radiators: one at an ideal length for 40 meters and above, and another–much longer–for 80 meters and above. Any advice and personal experience from KX1 owners would be much appreciated.
Perhaps most importantly, it’s only now dawned on me how much I enjoy making the most with self-imposed limitations or “trying to make lemonade with lemons.”
Do you feel the same? I’d love to hear your comments.
Not only will this antenna pair beautifully with my MTR-3B,KX1, and FT-817ND but I had completely forgotten I ordered it.
When I pulled the QRPGuys package from my post box, it was as if a little Christmas had arrived. I mean, is there a better feeling than getting a new kit in the mail–? I don’t think so.
Note: the following post was originally published on the SWLing Post.
Chameleon Antenna recently sent me a prototype of their latest antenna: the CHA MPAS Lite.
The MPAS Lite is a compact version of their MPAS 2.0 modular antenna system and designed to be even more portable.
Chameleon Antenna is a specialist antenna manufacturer that makes military-grade, field portable antennas that are low-profile and stealthy. Chameleon products are 100% made in the USA and their customers range from amateur radio operators to the armed forces.
Their antennas are not cheap, but they are a prime example when we talk about “you pay for what you get.” In all of my years of evaluating radio products, I’ve never seen better quality field antennas–they’re absolutely top-shelf.
Zeta
I’m currently in my hometown doing a little caregiving for my parents. I’d only planned to be here for a couple of days, but when I saw that the remnants of Hurricane Zeta would pass directly over us with tropical storm force winds and rain, I stuck around to help the folks out.
Zeta struck quite a blow, in fact. No injuries reported, but over 23,000 of us have been without power for over 34+ hours in Catawba county. With saturated grounds, the winds toppled a lot of trees and damaged power lines.
Yesterday, I wanted to take advantage of the power outage and get on the air. I couldn’t really do a POTA activation because I needed to manage things here at my parents’ house. Plus, why not profit from the grid being down and bathe in a noise-free RF space–?
I decided to set it up in their front yard.
CHA MPAS Lite
I had never deployed the MPAS Lite before, so I did a quick scan through the owner’s manual. Although the MPAS Lite (like the MPAS 2.0) can be configured a number of ways, I deployed it as a simple vertical antenna.
Assembly was simple:
Insert the stainless steel spike in the ground,
Attach the counterpoise wire (I unraveled about 25′) to the spike
Screw on the CHA Micro-Hybrid
Screw the 17′ telescoping whip onto the Hybrid-Micro
Extend the whip antenna fully
Connect the supplied coax (with in-line choke) to the Hybrid-Micro
Connect the antenna to the rig
Although I had the Icom IC-705 packed, I wanted to keep things simple by using the Elecraft KX2 I’d also packed since it has a built-in ATU.
Important: the CHA MPAS Lite requires an ATU to get a good match across the bands.
I wasn’t in the mood to ragchew yesterday, but I thought it might be fun to see how easily I could tune the MPAS Lite from 80 meters up.
I checked the Parks On The Air spots page and saw NK8O activating a park in Minnesota in CW:
He was working a bit of a pile-up, but after three calls, he worked me and reported a 559 signal report. Not bad at 5 watts!
I then moved to 40, 18, and 20 meter and called CQ a couple times to see if the Reverse Beacon Network (RBN) could spot me. I like using the RBN to give me a “quick and dirty” signal report. I was very pleased with the bands I tested:
Those dB numbers are quite good for an op running 5 watts into a vertical compromised antenna.
The KX2 very effortlessly got near 1:1 matches on every band I tested.
Of course, after working a few stations in CW and SSB, I tuned to the broadcast bands and enjoyed a little RFI-free SWLing. Noting 13dka’s recent article, I’m thinking on the coast, the MPAS Lite will make for a superb amateur radio and SWLing antenna.
Durability
Although the remnants of Zeta had effectively passed through the area three hours prior, it was still very blustery outside. I was concerned gusts might even be a little too strong for the 17′ whip, but I was wrong. The whip handled the wind gusts with ease and the spike held it in place with no problem.
One of the things I have to watch with my Wolf River Coils TIA vertical is the fact it’s prone to fall in windy conditions and many ops have noted that this can permanently damage the telescoping whip (the weak point in that system).
I’m pretty certain this wouldn’t happen with the Chameleon 17′ whip–it feels very substantial and solid.
Ready to hit the field with the CHA MPAS Lite!
I’m a huge fan of wire antennas because I believe they give me the most “bang-for-buck” in the field, but they’re not always practical to deploy. I like having a good self-supporting antenna option in my tool belt when there are no trees around or when parks don’t allow me to hang antennas in their trees.
I’ve got a park in mind that will make for a good test of the CHA MPAS Lite: it’s a remote game land with no real parking option. I’ll have to activate it on the roadside–an ideal application for the MPAS Lite.
At least 95% of the time I’m playing radio in the field, I use wire antennas and suspend them in trees.
Since I do a lot of park activations for the POTA program, trees are typically very easy to come by and most of the time the park office doesn’t care if I hang an antenna in their tree for a couple of hours.
For years, I’ve been using a heavy steel nut–a nut that would fit a very large bolt–as a weight and attach it to fishing line. I then simply throw the nut into a tree and pray the fishing line deploys properly. I have reasonably good aim, so–on a good day–I typically only need one or two throws/tries to get the fishing line over a branch. On bad days? Well… let’s just not talk about that.
There are some inherent weaknesses in the fishing line/monofilament system:
First of all, I’m lobbing a heavy metal object into the trees. If it ricochets–and it eventually will–it can come back down to earth and land where you might not want it to (for example, on your radio, on your car, or on your friend’s head). Fortunately, I’ve never hit anything or anyone as I’m careful to clear the area first, but unfortunately, I once had the nut hit a tree and come back down near me. That was a little scary.
Secondly, fishing line isn’t exactly recyclable and you simply can’t use it over and over. I get at most three deployments with a section of fishing line before it gets too stretched and unworkable.
Finally, fishing line is incredibly prone to tangle, especially near the end of the spool.
A Better Solution? The Arborist’s Throw Line
The arborist throw line is no recent innovation. For years, I’ve read recommendations from other ham radio operators who swear by arborist throw lines but I only recently decided to take the plunge after one very frustrating park activation where my fishing line knotted and almost got permanently stuck in a gorgeous tree. I’m very much a “Leave No Trace” kind of guy, so I was incredibly relieved when I was finally able to work the fishing line out of the tree.
I once talked with an arborist about throw lines and he stressed the importance of getting not just the line, but also a throw line storage cube. The cube allows you to both deploy and take up the line without any tangles or knots.
All in, I spent about $50.00 US for both.
Preparing the throw line
My arborist buddy gave me an important tip: the throw line needs to be stretched.
As you can see in the photo above, the throw line is packed in a bundle that’s easy to unroll. After you unroll it for the first time, though, the line has a “memory” of all those bends from its life in the package.
You can remove much of the throw line memory by tying one end of the line to a tree and stretching the line to its full length. The line is 150 (or so) feet long, so you’ll need an open space to do this.
The arborist in this video shows how this is done (I’ve queued it to the point in the video where he shows how to do this):
Knots
You’ll need to attach the throw line to the throw weight, of course.
There are a number of knots arborists use, but I’m a fan of the slipped simple noose knot. Perhaps it’s because it’s easy to tie even with semi-rigid line, it holds quite well and, most importantly, it’s easy to untie.
Looks like arborists use it too because when searching for an instructional video, the first result was from an arborists’ channel:
Throwing up!
There are a few different ways to launch a throw line into a tree.
Take my advice here: practice at home before you hit the field! It could save you a lot of embarrassment, although, admittedly, my at-home practice sessions gave my wife and my daughters good reasons to chuckle.
I’ve only been using the throw line for a little over a week, so I’m still sorting out which method works best for me. One thing I discovered very quickly, though: no matter which launch method I use, I can send that throw weight into a tree at least 60% higher than I could before.
No doubt, the throw line and weight really put the laws of physics in your favor!
Here’s a great video highlighting different throw line launch techniques:
In practice
I took the throw line to the field today for the first time and I’m very pleased with how effectively it works.
I was able to place my antenna on a much higher branch than I could have otherwise. It took me three tries today, but it had more to do with my poor aim. As with any skill, this will, I think, improve with practice.
The storage cube folds down flat and keeps the line from tangling
Besides the improved antenna height, I love that the line can be used over and over again. Also, it’s strong enough that should it ever get caught in a tree, I can pull it out without the line breaking.
I can also reel in the line at least three or four times faster than I could with fishing line. Simply flake it into the storage cube one foot at a time.
When the line has been stored along with the throw weight, you can fold the storage cube down flat, then fold and secure it into a compact triangle.
Are there any negatives with the throw line system? Here are a few I’d note:
Bulk. Even when packed down, the line in the storage cube take up much more space than fishing line. Although it easily fits in even my smallest backpack (the GoRuck Bullet), I’m not sure I’d take it on a long hike.
This system requires a little practice and skill–you can’t pull it out of the package for the first time in the field and expect perfect line launches.
The throw line is more conspicuous than fishing line. If you’re trying to be a bit stealthy–as many of us are these days during the Covid-19 pandemic–the bright yellow throw line will attract more attention and questions from other hikers/campers, etc.
One happy activator!
Even though it’s bulky by my standards, I see the throw line becoming a permanent part of my field kit and I expect I’ll use it on most of my POTA activations.
Have you been using a throw line to hang field antennas? Or do you use a different system? Please comment!
My good friend David Cripe (NMOS) has recently informed me about a new product he’s offering to the radio community via his eBay store: Kev-Flex Stealth Kevlar Antenna Wire. Kev-Flex looks like a superb option for field antennas of all stripes especially since it has an incredibly high tensile strength. It’s available in 75′ bundles, but Dave can also cut custom lengths. NM0S is also a trusted retailer in the ham radio world, so you can purchase with confidence.
Kev-Flex is a unique antenna wire manufactured exclusively for NM0S Electronics. The lightweight center core of the wire is made from Kevlar fiber, giving the wire its incredible strength. The Kevlar core is wrapped with six tinned strands of 30 AWG copper. The effective surface of the wire creates an effective skin area capable of handling well over 100W.
The cable is protected from the elements by a coating of UV-resistant black polyethylene. With a total diameter of only 1/16″ (incl. insulation) and a weight of just 16 feet per ounce, the tensile strength 125 lbs allows lengthy unsupported horizontal runs. Kev-Flex is ideal for extremely long LW-antennas and Beverages and is great for balloon or kite-supported antennas. Its low weight and high break-load makes it most suitable for SOTA activations and other field operations.
The outer insulation makes the wire kink-resistant, and its slippery finish makes it ideal for stealth antennas that must be passed through trees or other obstacles without snagging.
This antenna wire is sold in 75 foot long bundles, which is enough for a 40M dipole or EFHW. Two 75 foot bundles would make a great 80M dipole. Custom lengths are available on request.
Specification
– Kevlar fiber core wrapped with six 30 AWG copper strands – Weather-proof black polyethylene (PE) insulation, 1/16″ O.D. – Weight: 16 feet per ounce – Breaking-load: 125 lbs – Velocity factor 0.97
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