Lightweight Antenna Roundup – Episode 1 -The PAR TF 402010

My first HF transceiver was a Ten Tec Triton IV with analog dial, followed by a TT Argo, A Yaesu FT101, and then one of the original, “shack in a box” radios, the ICOM IC706 (and later a MKIIG). For reasons mentioned in the previous post on this blog I moved on to running a Yaesu FT-857D, a FT-817ND, and an original FT-817. That gear, along with an assortment of V/U/SHF equipment for VHF contesting, and various FM HTs, was the basis of my experience with transceivers. I got to know what I liked and what I didn’t. The Triton IV was the most fun CW rig I have ever used. The receiver was easy on the ears, the QSK was fantastic (like listening to yourself on receive), and it was fairly portable. The IC706 rigs were more versatile, covered more bands, had more power, and included at 20/70cm all mode. And it wasn’t a bad all-mode. After seeing my gear pile dwindle to almost nothing I started putting together a new station. I was looking for something fun and portable and found myself looking at the uBitx. I worked up one kit but just felt like it was not going to handle what I wanted to do. Then Xiegu released their G90 and that radio got me back on the air for over a year. It’s a great rig, but it came with the question of what antenna to pair it with?

Having used wire dipoles and a few commercial multiband verticals for fixed operation, and hamsticks, base loaded whips and other compact designs for mobile use, I had something to refer back to. My experiences with those mobile antennas was not great. Yes they work. But no, they are no comparison to a full size antenna. I used those in both fixed and mobile setups and I was happy for any contact I could make. To be honest hey were not good performers on either transmit or receive. Once band conditions improve you will be able to regularly work some sweet DX at 20W into a 20M hamstick on a mag mount. Now is not that time. If you can’t put up a perfect antenna, at least try for the least-bad antenna you can manage.

It turns out that while I was off not paying attention to ham radio equipment there has been an explosion in “compromise” designs like end fed wire antennas and they can be built/purchased to suit anything from an altoids-tin rig to a legal limit linear. The development of these antennas revolves around two fundamental designs: A half-wave radiator with a 49:1 un-un at the feedpoint; or a 9:1 balun feeding a non-resonant wire. In practice the use of a counterpoise is either unnecessary or misunderstood. From an optimal antenna standpoint these designs leave much to be desired. The matching unit is being asked to make a large impedance transformation into a rather blunt radiator, without the typical array of ground radials or even a counterpoise of any kind. However, from a real-world standpoint these designs are proving to be both effective and easily erected while also being cheap to build. That is rare.

After perusing many different designs I purchased the PAR 402010 Trail Friendly. It is advertised as covering three popular bands with no ATU, and it is light enough to be supported by just about any support. This is a design antenna with a history of being made by several builders and Vibroplex now markets them with the PAR branding. It features a 41′ lightweight insulated/stranded wire radiator with a 40M trap to make it resonate on both 40m and 20m, and it will also load on parts of the 10m band. The lightweight build still feels sturdy, and has proven durable over a year of regular use. The tip of the radiator can get mashed up a bit, especially if you have a mast collapse. Note my use of a heavy wrap of electrical tape at the tip of the mast. It helps with setup and fits in the collapsed tube.

About that mast… (12M Spiderpole Mini-Review Alert) At the same time I was searching for antennas I found another member of the Vibroplex line, Spiderbeam, and their 12-Meter Spiderpole. Often nicknamed “the beast” It’s built like a tank and can hold up much more than this little low-power wire vertical. Interestingly they do fit like they were made for each other. “The Beast” isn’t a backpacker pole unless you are a glutton for punishment or take your Cross-Fit habits onto the trails. It isn’t terribly compact, and it isn’t light. What it is is a borderline overbuilt 41 foot weatherproof antenna support.

The Spiderpole is overkill, a luxury, though a versatile luxury at that. It is a big, heavy telescoping mast and needs to be well secured at the base. It has more wind load than I guessed and exerts a lot of leverage on that base section, so you want it to be well secured while avoiding hard points where the fiberglass tube wall could fail under a sudden or heavy wind load. The upside is you get a 41′ vertical skyhook. Nice. It also shrinks the footprint compared to what you need for a sloper or inverted vee and allows you to work where there is no overhead support. I am surrounded by beaches, so something like this lets me operate from more locations and not be limited by the presence/absence of a large tree(s) and I create less of an attractive hazard for lookie-loos. It appears to be a law of physics that as soon as you put up an antenna some random mammal will walk directly into it within 5 minutes. All you can do is pad the odds in your favor.

Very Vertical

I was curious how this antenna would perform, especially compared to a 9:1 unit I had built and used on this same Spiderpole support. Mine is the basic trifilar design over a T200 core. The 9:1 works, but I always feel like I am working “up-hill” with it. That perception is based on ability to work stations I hear, and the signal reports I receive. There are worse options than a 9:1 into a chunk of wire sized to a convenient non-resonant length, but it feels very lossy in operation. When I first rigged the PAR I had my doubts. Rated at 25W SSB it isn’t much to look at. The matching unit is smaller than a fun-sized candy bar, the wire looks like overbuilt dental floss. Once I attached it to the Spiderpole and got it fully extended the ultralight wire It seemed out of balance being supported by “the beast”. Happily I was more than surprised at how well it performed. I observed much more parity with the stations I was hearing and working and logged several nice stretches of contacts on both FT8 and SSB. I was using it with both a Xiegu G90 and a Yaesu FT-991A, and aside from needing to watch the power output it did what it says on the tin. Three bands, no waiting. I don’t hesitate to set this up for a quick evening of casual operation since setup and take down require about 10 minutes each.

Here it is lashed to a deck railing in my back yard (or “garden”. You know who you are). If I was expecting gusty conditions I would have a 4-way support at the top rail and the base. In calm conditions the bongo ties hold up just fine. Just use as many as you dare. This thing puts a lot of stress on the support system.

When erected the matching unit sits about 3″ off the deck.

Technical Aside: These end-fed matching devices are indeed lossy. You don’t need to break out a calculator to know this. All you have to do is look at the designs for different power ratings. The size and number of the ferrite toroids (typically 43-Mix) need to be increased to withstand the increased field density of each higher power rating, and the heat that comes with it. A good portion, perhaps as much as 30%, of the power making it to the matching device gets siphoned off as resistive/heat losses. [tl/dr YOU ARE MAKING HEAT NOT ERP] But hey, you know the setup is a compromise going in. That compromise is lower overall efficiency in exchange for ease of setup and portability. I found that going from 5W to 10W output caused a sizeable step change in the contacts I was able to make, but that is to be expected, since my ERP was probably going from 3W to 7W. Certainly you can make a lot of contacts with this antenna, but you will probably be be several dB down from where you *might* be on a more efficient antenna system. The upside is that you can get on the air quickly with not much fuss, which translates to more time operating and less time reading long winded blog posts. But I digress.

A Phalanx of Bongo Ties and Clamps

One big question with “the beast” is how to support it, and one of those lightweight drive-on flagpole mounts is not likely to get it done. I currently use a phalanx of bongo ties, woodworker clamps, ratchet straps, and U-Bolts. None of them are perfect but I can lash it to a variety of improvised bases. I’m thinking a 36″ tubular support welded to a 2″ trailer hitch is about what it would take to have real peace of mind with this thing while operating car-portable.

Wrap Up: My feeling about this antenna has done nothing but improved each time I deploy it. I feel like this particular design gets overlooked. That’s a shame because it is a solid performer. It hears very well, is easy to tune, and I am always surprised at how well it works. We can hope all we want to have a low loss resonant radiator over a dense field of copper radials, or a big dipole/doublet/windom/curtain a half wave up on solid supports, but it seems that what many/most hams typically need is a way to get on the air under sub-optimal conditions. We also want to be able to actually operate once we get set up. What I would love to see is a 200W CW Rated version with the same 41′ design. Right now I guess I have to build one. Vibroplex has a potential two-fer on their hands if they can match a 41′ triband wire vertical to their affordable heavy-duty 12m Spiderpole. That opens it up to running CW or digital/RTTY at a full 100W and having a solid safety margin at the feedpoint.

I hope this was informative, or at least I hope you had a good nap. 73, N1QDQ

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