CHAMELEON (MPAS) PORTABLE ANTENNA REVIEW-ZL3GAV
(5,350 FT8 contacts, 156 DXCC entities worked over 5 months)
After 35 years I finally made an effort to obtain my amateur radio licence in January 2018. While my focus is with satellites, I was interested in HF, but more for listening and casual contacts. I intend to relocate, so a permanent HF antenna installation is not currently feasible.
With this compromise in mind, I researched portable vertical antennas that could easily be assembled and disassembled, and provide wide band coverage with reasonable performance. After navigating through the myriad of products available, including several where you use tuning accessories with alligator clips etc. to find resonant points, they were too convoluted for my requirements. Suffice to say, there are plenty of options, and many opinions available; ultimately you should make a choice that is best for your circumstances.
With no real desire to work HF voice, only using it infrequently my interest is the digital modes of WSJTx (current version 2.0.0), partly because of their passive operating nature. I mostly work from home, with FT8 running in the background and interacting with the software/radio without the distraction that voice modes would create is important for me. I believe we should embrace Digital modes enthusiastically, if we are to encourage newcomers to the hobby and keep them motivated. It is a similar analogy to the halcyon days when AM emerged, and CW was then the only available mode; subsequently came SSB etc. These popular new digital modes represent great opportunities, not a threat. No doubt within the next five years the levels of encryption and weak signal reception capability will have taken a further leap. At the bottom of the current solar cycle #24, FT8 has provided astounding DX results, and much fun for many living in high noise environments, that make other modes unusable. I don’t regard amateur radio is well served by the detractors of digital modes, there is enough scope for everyone to enjoy whatever niche they like. Digital modes such as WSJTx is about experimentation and innovation, much like the early days of amateur radio.
The transceiver I use is the popular Yaesu FT-991A, a “shack in a box” with HF 160m to 6m and VHF/UHF capability. The Yaesu has a built-in antenna tuner designed to match impedances within the range of 16.7 Ohms to 150 Ohms, corresponding to an SWR of 3:1 or less. (The Chameleon CHA HYBRID-MINI base has a 5:1 transformer, so the Yaesu will tune from 1.8 to 54MHz in the desired configuration.)
GETTING THE CHAMELEON ANTENNA:
I found the Chameleon antenna online via Google and read reviews that were mostly complimentary. I liked the simplicity of the www.chameleonantenna.com website with plenty of useful product information and technical resources without the hard sell. With the modular design, you pick and mix the components you require, some of the discretionary items such as counterpoises are optional, but I would recommend as essential to maximising performance.
What is problematical living in New Zealand is the exorbitant freight charges often incurred to get stuff from the USA to here. Some companies like DX Engineering and MPD Digital have an enlightened approach with tracked UPS or DHL couriers at a reasonable cost. Other vendors seem not interested in international customers where the quoted freight charge can be more than three times the cost of the actual product; this is crazy. It was refreshing that in corresponding with Carl Lavoie, the owner of Chameleon who always answered quickly they would ship freight free to New Zealand. Upon deciding the required configuration and paying via the secure PayPal credit card portal, the antenna arrived within a week.
The configuration I bought as per the Chameleon Product codes were as follows. (The website exhaustively covers antenna design, propagation and detailed product specification. so I have not reiterated these here.)
CHA MPAS + CHA MIL EXT + CHA CAP HAT + CHA-COUNTERPOISE KIT + CHA 50’ COAX WITH INTEGRATED RFI CHOKE + CHA PIKE MOUNT
The build quality is superb; it can all be put together in less than 5 minutes. The only finicky part is assembling the CHA CAP HAT, but this is one off, as I have no intention of dissembling it. The antenna is mounted on an inexpensive speaker tripod on the backyard lawn. (Yes, every week it has to be dismantled to mow the lawns.) The CHA SPIKE is used to anchor the tripod, and the three legs are drilled with tent pegs inserted also used to further secure the tripod. I run an earth wire from the top segment of the tripod to the bottom, so the whole “structure” is in theory earthed. The entire whip is 5.3m (17.4’), and the tripod at 1.8m (6’) takes the antenna to 7m (23’) in height. From the “dancing chameleon’ video, the whip always returns to the upright position, this jiggling about in the wind does not seem to adversely SWR.
The antenna was commissioned 24 July 2018 and has not been dismantled. (sans lawn mowing duties.) It has withstood 90Km/h (56 mph) winds and temperature extremes from -6C (21F) to 35C (95F). The documentation refers to the CHA MIL EXT not being weather resistant, stating “for temporary installation only…” There is so far; no deterioration other than some light rust on the spring of the jawmount clamp. With the collapsible telescopic sections, I use Permatex Aluminium anti-seize lubricant. This was $NZD5 ($USD3.40) a tube which will last a long time. The four counterpoise wires, plus the 30-foot antenna wire are spread equidistant across the lawn/garden in a star pattern and anchored with tent pegs. These are kept taut to avoid being a trip hazard and possible damage to the antenna. The low tech solution of a clothes peg with a piece of string is used to set the same distance of the counterpoises from the tripod during weekly lawn mowing duty. All of the bits I need in the event I want to take portable at some later date are stored in a plastic Tupperware bucket. In all it is compact and lightweight solution, and unlikely to get much attention on airline travel as checked luggage.
The only minor critique is the PL259 connectors on the 50’ RG58C/U coaxial cable which are crimped are not robust and they were replaced. (The current image on the Chameleon website seems to show improved connectors.) I know we are buying American, and are old enough to comprehend imperial measurements, but the use of dual metric descriptors in the documentation would be helpful for international customers, which I suspect there are a growing number.
From 160m to 6m with the Yaesu FT-991A internal tuner, all bands will tune to a perfect 1:1 VSWR. The non tuned SWR readings are better than the Chameleon published test results.
The SWR readings without the internal ATU are:
With the “star” counterpoise configuration, using the extra leg from the antenna wire supplied, given propagation variabilities, there is no scientific way of determining the results with, or without the extra counterpoise, or whether the Capacitance Hat (CHA CAP HAT) makes a difference? I would be interested in adding another set of counterpoise radials; I think the more used possibly, the better as this would be consistent with vertical antenna design theory.
Initially, I noticed specifically on bands from 40m downwards the SWR would deteriorate after moderate use. It transpired that the CHA HYBRID MICRO balun/transformer was overheating. Given the nature of FT8 modulation, according to the published specifications is 50-watt continuous duty cycle (CW, AM, FM, RTTY), 100 - watts intermittent duty cycle (SSB and SSB based digital modes). With FT8 the transmission sequence is 12.9 seconds of the 15 second transmit cycle, then 15 seconds receive cycle and so on repeated. It was noticeable the latent heat was building up when operating on the lower bands where the antenna is not as efficient, resulting in the transformer getting hot. Dropping power to 50 – 60 watts would see the 1:1 SWR restored as the heat dissipated.
I replaced the CHA HYBRID MICRO unit with the CHA HYBRID MINI balun/transformer which is larger and rated at 250-watt continuous duty cycle (CW, AM, FM, RTTY), 800-watts intermittent duty cycle (SSB and SSB based digital modes). I wish I had looked at the specifications more closely as the CHA HYBRID MICRO was always going to marginal for my intended operation so, this was a costly mistake. With us at the ‘bottom of the world’ I prefer to run 100 watts on FT8, it is a low signal mode, not a low power mode.
From Day One I was amazed at the signals being received on FT8. From my location in Christchurch New Zealand for the period from 24 July 2018 to 31 December 2018, 5,350 FT8 contacts were made from 156 DXCC countries with all 50 US states worked (WAS). I am not actively into awards, setting my own challenges but it has been a fun journey. (In LoTW DXCC and WAS criteria met and also on the specific 30m and 20m bands over 100 DXCC has been gained.) I thought I had a good grasp of geography but some countries worked had me reaching for an atlas. With my late entry into the hobby the chance of working these countries in a non digital mode are zero. FT8 is a great way to understand and put propagation theory into practical use.
Using the omnidirectional Chameleon vertical, I don’t need to worry about which way to point, so I see it all. There are times when I receive signals that local users on more sophisticated directional antenna systems don’t see, other times I am smashed to oblivion. The sweet spot performance bands are 30m, 17m, 15m and 10m where most stations called will respond. 40m is a “zoo” most evenings here, so I don’t persevere with it too much. On 80m and 160m the antenna is good for Australia, New Zealand and South Pacific and have worked Alaska on 80m. The documentation mentions about limited skywave performance on these bands, but on the higher bands I think the results are exemplary, the proof is evident with the stations worked. Over the 2018/2019 Summer season, so far, 100 plus FT8 contacts have been made on 6m to Australia, New Zealand and Fiji. With FT8 it is the distant skywave propagation that is useful. Near Vertical Incidence Skywave (NVIS) propagation is intended with the antenna use on 160m and 80m. I have tested NVIS on these bands on SSB voice and the antenna worked well. SSB voice is not of great interest to me (as you would have gathered by now) I have worked Australia/New Zealand on all bands and France on 17m without actively pursuing voice QSOs.
In summary, I could not be happier with the Chameleon MPAS antenna system. I had set myself a personal target on FT8 initially of 50 countries and 3,000 QSO’s in 2018, so that was soon eclipsed. This antenna system represents great value and the versatility of portability. Chameleon Antennas produce a number of other interesting products I will look at in the future.
(I don’t seek QSL cards, but all of my contacts are uploaded in real time LoTW, eQSL, Clublog, HRDnet log and QRZ.com. You can check whether you are in the log on the ZL3GAV.com homepage. I also try to regularly (but could do better) update @ZL3GAV on twitter, so please follow me. I can be emailed at firstname.lastname@example.org.)
The following is a snapshot of my HRDLog.net DXCC summary as at 1 January 2019; the green ticks denote a DXCC entity matched and confirmed by LoTW.
(This website is kindly curated and sponsored by Move37 Consulting, Independent Information Technology Consultants www.move37consulting.com)
version 1.4 ZL3GAV May 2019 - (all trademarks acknowledged)