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.
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.
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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