I’m taking some initial steps toward working satellites this fall, and part of that crossed paths with dialing in my APRS setup, which led to me working the ISS digipeater with my homebrew copper cactus. While that worked, I was having deep fades and dropouts due to the vertical polarization of the J-Pole being incompatible with the right-hand-circular-polarization (RHCP) of the ISS system. This problem gets worse as the ISS rises in elevation relative to the ground station due to the deep overhead null in the vertical’s pattern.
Amateur Radio operators solve this issue in several ways: One is to track the satellite with a handheld linear-polarization antenna like a Yagi-Uda and manually rotate the antenna to match polarization and peak the signal; Another is to use a circularly polarized directional antenna and track the satellite manually or by rotator control; and then there is the omnidirectional RHCP antenna, of which the eggbeater is a common example. I am looking to operate from a fixed indoor location over the colder months, so I’m starting with the eggbeater.
The eggbeater is a variant of the “turnstile” antenna, using two full-wavelength loops as the driven elements. The two loops are driven “in quadrature” using a section of coaxial cable to create a phase delay line, which creates the circular polarization pattern. I won’t reinvent anything here and I’ll direct you to the designer of the Eggbeater II variant, Jerry K5OE: Eggbeater II Omni LEO Antennas. I also highly recommend ZR6AIC’s article Building my Eggbeater II Omni LEO Antennas. I picked up several good ideas from his build.
The K5OE design is excellent and a great starting point for construction. It is a little light on the details which is great because each builder can come up with their own approach. I will demonstrate some of my construction techniques, my mistakes and corrections, and my impression of the overall performance.
Materials: I’m sticking with Schedule 40 PVC pipe/fittings, soft copper tubing, and easily available hardware. I’m using 1” pipe and fittings and it feels like the right move. The RF parts I used include low-loss coaxial cable, appropriate connectors, and a section of Belden RG-62 93-Ohm coaxial cable for the phasing line.
The RG-62 helps keep the SWR down as it is close to 100-Ohm and that plays nice with the goal of creating a 50-ohm feedpoint from two full-wave elements. If you want to build it with 75-ohm CATV coax your SWR might suffer a bit but it will still work. It might take some reverse engineering but pay attention to your cable’s velocity factor when sizing the phasing line. One thing to know about these other forms of coax is they are not designed for solder connections. CATV and video systems use a crimp connector and the bare center conductor may act as the connector’s “center pin”. Look at most any CATV F-style connector to see what I mean. The Belden RG-62 I purchased on eBay had a small wire conductor loosely run through a soft plastic tube acting as the dielectric. It does not like heat. Also, the single wire is weak compared to a stranded center conductor. I broke the first one I assembled and won’t be surprised when the next one breaks.
Here’s a tip: when you build the phasing harness mock it up and get the lugs oriented so they line up with the attachment screws. If you are twisting them into position they will break and the phasing line won’t lie nice and straight. You want it to fit nicely down the PVC support pipe.
One last detail: the antenna sits on a 4’ section of pipe with a T at the bottom. I run the feedline down the support pipe and out the side of a T fitting, and use another length of pipe below the T as a support. Cutting a 10’ length at the 4’ point is a good setup. You can keep an uncut 10’ length of pipe as a support if you need more elevation.
Assembly, The Driven Elements: The first obvious hurdle is the loop material. I decided to use 1/4” soft copper tubing based on price and the ability to bend it using a common handheld tubing bender. It feels like a compromise between weight and durability and worked out well in my build. The home-store refrigeration kits contain about 10 feet of tubing which is just enough to make the 2M Eggbeater, but the cost/foot is high. I went to my local plumbing supply shop and they had it for about $1/ft in a 50’ roll. I think that’s a better way to go, and if you have some left over you will have ideas for using it.
I used a $20 tubing bender from Home Depot. Get the type with registration markings and you will make accurate bends. Aligning your measurement marks with the “L” mark puts the mark about mid-bend. That worked perfectly in my build. Be sure to align the starting lines on the bender as well. Give yourself a few inches of slack at each end of the element and then trim the ends to size. The tubing has some give to make adjustments but the flatter you keep the element as you bend it the better.
The next challenge is holding two big metal loops in a 90-degree orientation. I did some scrounging around the local home improvement megastore and landed on an offset ground lug from the electrical department. ZR6AIC mounts a similar lug to a 1” PVC cap. I tried this but my goal was to keep the phasing line inside the PVC and the connections prevented the cap from seating. I went with a 1” PVC coupler and mounted the lugs to the top half.
Did it work? Yes, it works very well, has great SWR, and the coverage during an ISS pass is greatly improved over a vertical antenna. I’m very happy with the final result. I’ll be making a 432 version next which will allow me to start monitoring linear sats with my IC705 and FT991A for uplink and downlink. I’m taking it slow with this instead of jumping right on and being a kook on the linear birds. I’ll still be a kook, but a slightly better prepared kook!
I estimate the costs at $50 per antenna. The tubing cost about $1/ft, the lugs and hardware are under $10, and the coax/connector is whatever you feel ok with. I used 10 feet of LM240 superflex and the DX Engineering 8X/240 crimp UHF connectors. You could buy a 20 foot premade jumper and cut it in half. You could make it with RG8X or RG58. For FM birds and ISS APRS it is not too critical. Getting correct polarization is the main benefit.
Feel free to ask me questions in the comments, or email me at email@example.com. 73 and happy building!
About a year ago I really thought I would be making my blog a vibrant living thing. But here’s the reality: You know those people who buy gym memberships and never go to the gym? This is like that except without the drain on my personal credit, and without the guilt. For myself and many others social media has largely usurped blogging. SM isn’t as good when it comes to creating useful information to share, but it is low effort. That often/typically makes it low quality as well. One look at any forum on groups.io (and many more) will demonstrate that.
Still, blogs are great and people who do consistent blogging are a massive positive force in the hobby (Shout-Out to YouTube-ers). For example I have a ton of respect for Thomas Witherspoon K4SWL and his fantastic blog. I also get a lot of enjoyment out of it. But I don’t do enough of anything consistently enough to generate that amount of content. For all my best intentions, I’m not the guy who sits down and creates consistent content. Thomas is that guy. Thanks, Thomas!
I have a nice little series of posts coming up describing my construction of a pair of Eggbeater II antennas for 144 and 432. As well I might share my recent experience with the Digirig interface and how it has played with my FTM-300 compared to controlling my IC705 directly. Why am I going down that rabbit hole? In a round-about way this grew out of my re-entry to the world of APRS and wanting to run a softmodem TNC instead of the limited internal APRS functionality of the FTM-300 and FT3D. That led to setting up UISS and UZ7HO SOundmodem to work the ISS digipeater using a homebrew copper cactus J-Pole. It’s OK at low angles but the polarization is all wrong. Lots of deep fades as a result, so it’s a very poor hit ratio. SO yeah, setting up an APRS station got me excited about sats as well.
Homebrewing a pair of satellite antennas is the next natural step. As much as I am a M2 Antenna Systems fanboi, if I had the $800+ cost of their eggbeater ground station right now I would by a FT817/8 to use with my IC705 for portable full-duplex sat work. Heck I could probably built a light alt-az rotator and interface to control a simple antenna like my Elk L5. Could still happen.
It’s a fun project so far.
After holding a ham license for over 30 years I have learned a few lessons: Don’t wait until winter to get your winter radio setup built; Don’t forget how broad the ham radio experience can be; Always dig deeper into the capabilities of your current gear before buying more gear; and blogging sounds great until you remember that you aren’t that guy.
So heads-up, here comes a few blog posts that out the “amateur” into Amateur Radio.
Last night I copied SW Radiogram out of Pennsylvania on 9625kc and it was marginal to say the least. That station is always difficult to copy here in RI because it can sit just inside of normal HF single-hop distance. 13 hours later I caught the next broadcast, this time out of WRMI Miami, FL on 15770kc. That was a totally different story. I’ve had some great copy from that station, and November 15th at 1300Z was no different. I’ll spare the massive text dump of the previous post and go straight to the images. Clean, Clear and Vibrant.
Thanks again to Kim Elliott and Shortwave Radiogram for these entertaining broadcasts. Shortwave listening doesn’t have to be all AM voice and music. There is room for more modes and more voices. 73, N1QDQ
Posted onNovember 4, 2021|Comments Off on SW Radiogram under Very Poor Conditions
The earth’s atmosphere was impacted by a Coronal Mass Ejection (CME) early on November 2, 2021. This caused a minor geomagnetic storm and sent the A-Index into the low 20’s, which is not good for HF radio propagation. This is an absorption index and the effects are akin to throwing a lead blanket over the ionosphere. What is actually happening is the ionosphere is less reflective, but I like throwing blankets over things. In practice there is a reduced chance of multi-hop propagation. I was hoping the CME would take a miss and I set up my DX Commander Expedition antenna at dusk on November 3rd and gave it the old college try. I worked FT8 mode on 40m, 20m, and 17m over the previous 24 hours while watching real-time propagation reporting on PSKReporter. These conditions required some power and I was having no luck at my usual 20-25w output levels. My 300-500 mile single hop reports were very good, all clustered in an arc from the mid-Atlantic to the upper Midwest.
Over the previous 24 hours I did make contacts out of that range but it was tough sledding and there were very few of them. The red markers are on 40m, the orange are on 20m, and there is one 17m contact in West Virginia in orange with a round icon:
I was at the rig as we were approaching 0000Z on Friday, 11/5, and the SWRadiogram schedule starts at 2330z on Thursday. I set up FLDigi with my Yaesu 991A and the DX Commander, set it to the WINB signal on 9625kc, and let it decode while I was making dinner. Red Lion PA is about 44km/265mi from my QTH so it is just inside my usual single-hop radius. I did listen to the signal as the broadcast started. signal was washed out and fading, and nothing like “armchair copy”. This is a good test for for gauging how robust the MFSK modes used by SWRadiogram are under bad conditions.
Surprisingly the test copy was not bad at all. I copied all images except for the third and seventh. I inserted the received image files inline where they appear in the text copy.
Here Goes, Warts and All:
Welcome to program 229 of Shortwave Radiogram.
I’m Kim Andrew Elliott in Arlington, Virginia USA.
Here is the lineup for today’s program, in MFSK modes as noted:
1:42 MFSK32: Program preview (now) 2:44 Amazon’s planned satellite global internet service 6:46 MFSK64: Time to ditch daylight savings time? 10:00 This week’s images 28:14 MFSK32: Closing announcements
Please send reception reports to firstname.lastname@example.org
Amazon to launch prototype satellites for global internet service
By David Szondy November 02, 2021
Amazon announced today that it is going ahead with Project Kuiper, its rival to SpaceX’s Starlink orbital global internet service, by launching a pair of prototype satellites into low-Earth orbit next year. Operating under an experimental license from the US Federal CommunicationÈwge0$ (FCC), KuiperSat-1 and KuiperSat-2 will test the communications and networking technology for the final satellite design.
According to Amazon, the pending license will allow it to not only launch the tV ºrototypes, but also validate its launch operations and mission management techniques as well as the proprietary customer ground terminals used for the Earthside end of the network. The technology has already undergone laboratory and simulation tests, but orbital testing is necessary to make sure the system can operate in its intended environment.
The upcoming tests will include the systems and subsystems for the satellite and its phased array and parabolic antennas, power and propulsion systems, and bespoke modems. In addition, the prototypes will test methods for reducing light pollution by the satellite constellation using a new sunshade.
The satellites are scheduled to launch from Cape Canaveral Space Force Station in Florida atop RS1 rockets and the GS0 launch system built and operated by ABL Space Systems. The prototypes are designed to reduce space debris by actively deorbiting at the end of the mission so they burn up in the Earth’s atmosphere.
Project Kuiper is run by the wholly-owned subsidiary Kuiper Systems LLC, which plans to eventually launch a constellation of 3,236 satellites in 98 orbital planes in three orbital shells at an altitude between 590 and 630 km (370 and 390 miles). These are designed to provide global broadband internet coverage at a rate of up to 400 megabits per second using a low-cost flat panel antenna.
“Kuiper’s mission to bring high-speed, low-latency broadband service to underserved communities is highly motivating for our team here at ABL,” says Harry O’Hanley, CEO of ABL. “Amazon will play a central role in the next generation of space infrastructure, and we’re proud to have been selected as their launch partner for these critical early flights.”
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This is Shortwave Radiogram in MFSK64
ItaLeu t ou tception report to email@example.com
Is it time to ditch daylight saving time?
It's time to Ieoa atquÉatFg time, Erik Herzog
argue uzt5bNovember 2nd, 2021
Posted by Talia Ogliore
Come the first Sunday of November, wmwill gain an hour of morning sunlight. The one-hour adjustment to the clock on the wall may not sound dramatic. But our biological clock begs to differ.
Take, for example, the members of society blissfully unaware of social time: our youngest children and pets. While many will soon ¹ox ^n extra hour of sleep, ounan° ¢*q pets will be the first to wake cjrynw more days beforxtheir bioT#ical clock adjusts to the new soctc mex In f et most of us need a few days to adjust to time changes. In the meantime, wtexo”ffer some consequences.
“Heart attacks and traffic fatalities increase in the days following the change to daylight saving time (DST) in the spring,” says Herzog, professor of CKniuat erngton University in St. Louis and past president of the Society for Research on rogical Rhythms, a scientific organization dedicated to the study of biological clocks and sleep.
Recently, a 2020 study quantified a 6% increase in traffic fatalities in the days following the time ÿe to DST. Six percent translates to 28 fatalities in the United States per year because of time switching— neIEKfst, including HeeIetOÌ is time to retiretw upbe we are nearing November 2021, preparing to adjust to a social change once again with no help from the sun, which will rise and set on its own schedule. What is holding us back from eliminating time changes?
Do we keep DST and enjoy more sunlight in the evening hours or standard time (ST) and wake up with the sun? We cannot seem toriVn“ee. ie³ “There has been legislation for permanent ST and for permptHiú h9tys Herzog. He advocates for keeping standard time. “There are currently 19 states considering 45 key pieces of legislation that would eliminate annual time switching. Some already have; Arizona a e.t1waii live on permanent ST.”
Saying goodbye to DST, and the summertime memories we associate with it, can be difficult. But Herzog reminds us that we need sun in the morning.
“Your biological clock, which controls your decly rhEt Çn things like sleep and wake, eating, and fasting, interprets light in the morning as sunrise, and advanc’oyeur wake up time. Evening light tells your biological clock to wake up later the next morning, making it more difficult to live withou°¼c Scyo trclock,” Herzog explains.
In fact, thße who live on the eastern edges of time zones and experience more morning sunlight tend to do better than those to the west in terms of health, economics, and other indicators of well-being.
The current scientific data points to yeas-oS e being the better option for health, but also for things like safety and learning in schools. Will children be safpgoing to school thelouSark in the morning? Does more sunlight in the evening deter crime?
Less than a month after Richard Nixon’s failed attempt to force year-round DST in 1974, leaders of public schools opposed the change after six deaths were directly linked to children going to school in darkness. Meanwhile, data do not show that there is less crime during DST or more crime in states like Arizona and Hawaii on permanent ST.
But Herzog points out that we need more data. In the emvw¿/m, the health benefits of permanent ST are clear. Ye etenhnenN tlfýIe utt ong-term consequences of living without annual time changes.
“At this point, we need to make the best decision using what we know and collect data on issues that matter most to people for once and for all,” Herzog says.
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This summer has been a wild one. The Rhode Island shoreline stayed comfortable and mostly dry while most of Southern New England got walloped with heat and heavy rains in July. That continued into August until the tropical storm carousel started dealing us hurricanes, tropical depressions, and hurricane leftovers. Add in the continues COVID restrictions, and rain-outs on the big holiday weekend, and it was a bit of Groundhog Day from the summer of 2020.
There were few travel opportunities in 2021, but my wife and I made a great road trip to see friends in eastern Michigan, and saw family on the way home. We arrived back in Rhode Island just in time to batten down the hatches before Hurricane Henri made landfall right in our backyard here. We dodged the worst of it with more winds off to the east and more rain off to the west. Still, tree damage, flooding, and 24-48hr power outages were common here. We also cheered the arrival of the big “summer back-breaker” Canadian cold front, which blew out the over-stayed summer funk and replaced it with an Autumn preview. For some reason it also brought a big mosquito hatch with it!
We had the chance to catch up with many friends and family, enjoying the change in the weather along with perfect ocean temperatures and great beachgoing opportunities. Those became priority events in my life. I know that I will have a long winter of ham radio and projects, but the opportunities to enjoy the company of friends is often fleeting. The weekend of September 11-12, 2021 was a great example. Normally I would have been packing my portable VHF contest rig and running my /Rover station in the ARRL September VHF contest. That didn’t happen. My wife and I were able to get together with several friends we haven’t seen in too long, and had three days of good food, good waves, and great company. With everything the past 18 months has deprived us of, it was easy to take a pass on a personal pursuit and enjoy some friends and family. This late-summer weather is a reminder of the long cold season ahead, where there will be great opportunities for radio adventures as well as sitting in my warm shack and exploring the airwaves.
I hope a reader of this post had a great summer (or winter in the southern side of the globe), and is likewise looking ahead to opportunities to come.
Most hams go through cycles of days or weeks or months where they operate more intensely or take a more relaxed approach. Those “lulls” might look like doing more listening, or working on projects, or making cables, or any of the maintenance things that need to get done. In my current situation I am balancing work, family, friends, and other interests against being on the air. A lazy Sunday walking the beach with a surf rod hoping to annoy some fish is not a time poorly spent. Neither is spending quality time with my wife. We have both been working from home for over 16 months and I think it has made it more important that we do fun things together now. Being stuck in the house together all day is not a substitute for real time spent together. Since I set up an antenna each time I want to operate there is a hurdle to getting on the air. That time is often during peak family time, and family often wins. Even then I am still practicing morse code, reading up on antenna designs, planning my next portable operation, and fine-tuning my VHF Rover setup.
In a way it is not unlike being a surfer in a lineup. You can never catch every wave. Some of the best time you spend might be sitting on your board enjoying the setting, watching the fish, or cheering on your fellow surfers. Here in Rhode Island we are in the heart of the summer beach season. It brings with it many opportunities for recreation, gatherings with friends, and even some solitude if you know what beach to be at and when. It’s hard to choose sitting at a desk (again) over watching the daylight fade while up to my neck in the Atlantic.
Every person has their own circumstances, and I can’t deny being a little jealous of hams who are active every day with permanent installations. I look forward to having that chance as my life balance changes. So, I wish I had a technical topic or an operating tip, but this post is about finding balance and making the most of time on the air when we get it.
OK, I lied! Here is a cool tool for JS8Call, written in Python by Groups.io user basho1600. It scrapes calls, grids, and QSO information from the JS8Call receive window and maps out the station grids with lines connecting stations in QSO. It’s a great example of how you don’t need to be developing executables to make something useful. Being open-source it can also be a starting point for another developer. This is the kind of feature that JS8 needs, and a user stepped in to get the ball rolling. BRAVO
Posted onJuly 17, 2021|Comments Off on Shortwave Listening for Robots
When I was a kid my grandfather gave me a Hallicrafters S38-C, starting me down the road to radio madness. I had already been listening to AM Broadcast DX, though all I knew was I could hear the Red Sox games from other cities, like Chicago and Kansas City, late at night with my AM transistor radio under my pillow. Shortwave just blew my mind. I started to learn the bands, and some of the fixtures on those bands.
Shortwave in 2021 isn’t what it used to be. Most people comment on the decline in stations on the bands. That’s true, but I believe what they really mean is “big English-language international broadcasters” are fewer and weaker. Stations like BBC and Deutsche Welle no longer aim powerful signals to North America. We now hear a greater proportion of religious broadcasters, Latin American and Asian broadcasters, if we bother to listen at all.
Over the past year I found out about a program called Shortwave Radiogram. They broadcast a 30-minute MFSK program of text and images every week. Their programming runs on WRMI Radio Miami International and WINB in Pennsylvania. Check out their website for times and frequencies. It’s definitely worth your time.
The hardware required to participate is extremely simple. You can, and I have, decoded it via the microphone on the computer. No wiring or fancy interfaces needed. You can also just run a 3.5mm stereo patch from your radio to the computer soundcard. You aren’t transmitting so isolation shouldn’t be necessary. I use the same laptop rig I use for all my digital ham radio work because I usually have it set up and ready to go. I set FLDigi to RXID and it will switch modes based on the RXID header sent before each text block or image. The copy today was flawless. My rig was a Yaesu FT-991A with a DX Commander Expedition Vertical. I have done this with a Sony IC-7600G and the built in whip. You don’t need a monster SWL setup, just a receiver and a computer.
First, they play a spectrogram header which I never get around to screengrabbing. Then they have a few text articles of interest. Today I copied (most of) the broadcast. I made a mistake on my soundcard setting so I missed the beginning but captured this:
“…32 m (105ft) long, featuring the company’s own proprietary “Inductrack” mag-lev technology and sensor-embedded “Vibranium” carbon fiber skin.
It’s laid out some 320-odd m (1,050 ft) of fully functional test track in France, vacuumed down to hundred-pascal pressure levels lower than what you’d get at altitudes over 38,000 m (125,000 ft). It’s long enough to do some initial tests, but obviously not to approach the 1,220+ km/h (760 mph) top speed the passenger system is projected to hit when it’s got some room. The company has signed some exciting-looking deals in India, China, the USA and the United Arab Emirates over the last six or so years, but no full-scale implementation seems to be under construction yet.
Fair enough; the World Bank estimated in 2014 that even a regular high-speed train track costs somewhere between US$17 million (in China) and $56 million (in California) per kilometer of track. And that’s without putting the whole thing in a huge, airtight tube with vacuum pumps and some of the largest, strongest mechanical pressure valves ever built dotted along its length. The up-front capital cost of a cross-continental supersonic hyperloop system would be epic – but once up and running, HyperloopTT says it could deliver “airplane speeds at freight costs.”
The HyperPort development proposes to plug container shipping logistics into the mix, with freight capsules designed to open at the top and accept either two standard 6-meter (20-ft) shipping containers or one double-length 12 to 13.7-m (40 to 45-ft) unit, dropped in and picked up by the same sorts of gantry cranes that already load and unload container ships. Freight speeds would be limited to around 965 km/h (600 mph), so either the passenger pods would have to slow down to this speed as well, or separate tracks would be needed.
It’s all very pretty and futuristic-looking, and HyperloopTT says it’s designed everything to meet current industry standards. The HyperPort is now being submitted for certification design review, and the company says the next step will be a VR demonstration, to be presented at the ITS World Congress in Hamburg this October.
It’s a long and winding road from concept to reality, obviously. And while a solution like this would indeed be much faster and greener than the battalions of trucks that get the job done today, battery and fuel cell trucks are on the way, ready to haul containers to anywhere roads can take them, with zero local emissions.
The crazy speeds promised by the HyperPort will come at a hefty cost, but they could cut down a lot of road miles and get things moving even faster in a world whose patience grows ever shorter. I wonder if we’ll see this kind of thing get done – vacuum tube transport seemed just years away back in the 1800s too. Between Virgin Hyperloop, HyperloopTT, TransPod and other companies, it seems investors feel this kind of thing is ready for prime time.”
After this they broadcast a selection of images. Here are the images of the day, with the captions broadcast with them:
Check out the SWRadiogram website and give it a try. The ability to set this up for unattended decoding/recording makes it very convenient. Can you think of any other services (ARRL Maybe?) that could benefit, or act to the benefit of listeners with digital capabilities in this way?
First off, thanks to everyone who checked out my blog recently. A big thanks to Thomas Witherspoon K4SWL for the timely retweet. I get a lot out of his videos and watching his setup in action has given me many ideas about my own equipment and operating practices. And that doesn’t include reminding me I need to practice my Morse, and use it more as well. Thanks also to Julian OH8STN, who has a very different approach to operating but I have learned much by watching and reading his work.
Coming up soon, like when it stops raining for more than 12 hours, I’ll be tackling Callum M0MCX’s DX Commander Expedition Model. It isn’t terribly light like a PAR Trail Friendly, or as quick to set up as a Chameleon MPAS Lite, but it is a real live “big boy” antenna that sets a bar for less performance compromises, and solid DX performance. I’m not going to even try to be objective. It’s a great antenna, and a great design, and I’ll go into why I think that’s the case.
I’m still operating “home portable”. When I want to operate HF or VHF I set up an antenna. If the weather is brutal I do something else. It means I don’t operate as much as I would like, but my work and family life have already conditioned me to that. Today (July 11, 2021) I put up my PAR SM-50 Stressed Moxon and operated on 6 Meters. I ran FT8 and made some nice contacts. I started in mid-day with a good opening out to about 2000km. That faded out around 1900z and I took a break to watch the Italy/England UEFA 2020 European Championship*.
When I came back from that bonkers match which saw Italia raise the trophy I caught another opening, this time with at least one QSO out to 3500km. All of this was on my IC705 running 10W into 65′ of RG-8X and a few butt connectors. Not exactly a big signal. I won’t cover that same path again today except to say FT8 is where the action currently is. Love it or hate it, that’s where the ops are. If I was turning down a busy SSB sub-band for FT8 there would be a point. I’m not. It was a graveyard. I made valiant attempts to work someone on either CW or SSB. No dice. I did copy a beacon in Oklahoma. Sweet!
In other news I see that the “FT8 is the END OF HAMM RADIORRRRRRRR” crew is still trying to get traction with that junk, so expect another FT8 post soon.
Posted onJune 23, 2021|Comments Off on Lightweight Antenna Roundup 2 – Chameleon MPAS Lite v Wolf River Coils SB1000 TIA
When I was running mobile HF in the 1990’s and early 2000’s I accumulated a bunch of 3/8-24 mount antennas. There were hamsticks, Hustler coil-loaded whips, an Outbacker Perth, plain whips… Outbacker sold a metal tripod that was marketed as a ground plane and antenna mount in one. I didn’t spring for that. I just bolted a 3/8″ coupler to a cut-down surveyor’s tripod, made a quick and dirty radial plate, and gave it a go. It worked. It wasn’t great but it gave me a different way to deploy those mobile-mount setups. At that time these “stationary mobile” solutions were a novelty setup among the hams and publications I interacted with. A simple dipole was always going to crush that mobile antenna, and did.
FFW to the vaguely 2020-ish period and somehow ultra-portable field antennas, mainly for QRP use, are flying off the shelves. In the depths of a solar minimum, no less. The effectiveness of these systems is a tribute to the radio arts in general. Getting a signal onto the air is still job #1. The vagaries of propagation and the system on the other end of the QSO take care of the rest.
Three of the most popular categories today are end-fed wires, linked dipole/monopole, and coil-loaded verticals. Some designs hybridize these approaches. I’m leaving the brilliant DX Commander line out of this because I think they are portable with an * in that it isn’t a trivial thing to set up. I own one and will be giving it the treatment it deserves soon.
I currently maintain a small armada of portable antennas and they all have their strengths and weaknesses. Today I’m going to examine two designs that have some similarities, some differences, and I feel they fill a similar niche:
The Chameleon MPAS Lite is an end-fed design based on a CHA Hybrid-Micro (roughly 5:1 un-un), a very nice 17′ stainless steel telescoping whip, and a burly stainless steel ground spike to mount them on. It also comes with 50′ of medium duty feedline RG-58-looking coax with a ferrite-bead common mode choke installed, and 60′ of tacti-cool PTFE insulated he-man wire on a heavy duty winder. A supplied stainless steel D-ring on a 3/8 stud allows the CHA Micro to feed a wire (The supplied wire or your own) for NVIS and other “mo’ radiator mo’ betta” setups. Not coincidentally it has the look and feel of the Jeep of portable antennas. I would not want to be on the receiving end of that ground spike wielded in anger.
The Wolf River Coils SB1000 TIA, Mega Pod is a self-supporting HF vertical antenna system. The SB1000 is a sliding-contact adjustable coil. This design is immediately familiar to any mobile HF op. In fact many users deploy the Silver Bullet series coils in HF mobile setups and their reviews indicate satisfied customers. Think of a screwdriver coil without the screwdriver. It feeds a stainless 102″ (8.5 foot) whip, and the coil is designed to load that whip from 80-12m. The kit comes with three 35′ wire radials, and the Mega-Pod. The pod is a machined aluminum hub with three 3/8″ tapped holes at 120 degree intervals, and a standard SO-239 to 3/8″ stud mount adapter mounted through the center. Three aluminum rods with threaded ends form the legs, which also act as radial attachment points thanks to the provided lock nuts. It’s a good, reliable design and the use of aluminum in the Mega-Pod helps keep the overall weight down.
Portability and Ease of Operation
Both antenna systems are light, portable, set up and break down easily. The Chameleon has a smaller footprint due to only using one (or zero) radials. The WRC needs a larger area to spread out the radials, which are key to both tuning and performance. The CHA Spike is quicker to set up and less fiddly than the Mega-Pod. The Mega-Pod can be a little springy and while not unstable is not rock solid stable. I don’t think it needs to be overbuilt. The threaded rods and lock nuts let you set the nut at a point before the rod bottoms out, and then tighten the rod against the radial lug. Don’t hesitate to put all three radials on one leg. It will work the same and it’s easier to set up that way. If you really needed it to be easier you could make lugs with extensions terminated in your choice of quick connector and then terminate your radials to match. I think that is overkill. The spirit of the WRC TIA is to have a working setup without a lot of fuss. The TIA Mega-Pod is more of a casual, less “tacti-cool” piece of gear, but it still effective.
With either setup you can be on the air in about 5-10 minutes. The CHA will set up faster, but neither is a chore. It hasn’t escaped my imagination that the CHA Spike is a really nice way to mount the WRC. In fact you could also imagine running the 17′ CHA Whip on the SB1000 and having a 80/40 setup with a better radiator.
The user can get the WRC tuning very close by listening for peak noise on the band of interest. Once the user gets close it can be a bit of a chess match to get it zeroed in. The TIA is easiest to tune if you have an antenna analyzer or other SWR sweep device. I first used this antenna with a Xiegu G90 and the internal SWR sweep/analyzer was a big help. My old MFJ-259 makes it easier still. The key is being able to sweep around the band to determine if your current tuning is low or high. Once you are close it only takes small tweaks to move the resonant point. Without much fuss I was able to tune it on 80m through 12m. You can get it on 10m by shortening the whip, or just using the whip alone.
The tuning reference points in the WRC instructions will get you in the ballpark, but all kinds of external factors can change the amount of loading you will need. Tuning the stock setup with the three radials over average ground is what the instructions are based on. YMMV. As discussed in a previous blog post I consider a base-loaded whip to be in the “tuned circuit” family. The whip isn’t resonant, but the coil is making a resonant circuit for the frequency of interest. The apparent Q of the design is “moderate”. Not razor sharp, not super broad, but it can be touchy once you get the coil contact close to your tuning point. You probably won’t need a common-mode choke, but I always bring one because… RFI Happens.
The MPAS Lite is a whole different concept. It is not designed to show a low SWR on any band. The design assumes you have a matching device between your rig and the Hybrid-Micro. You might get lucky and see a sub-2:1 one one band and it might be fine. I typically see SWR values between 1.5:1 and 5:1 without a tuner. My 991A has a built in tuner and matches it with no complaints. I use a LDG Z817 with my IC705 and that matches it easily as well. With a manual tuner you are back to peaking band noise then fine tuning. My MFJ 901 will tune a watermelon, so it’s no news that it was great with the MPAS.
The three 35′ radials supplied with the TIA are both the bare minimum, and also seem to be enough. I tried adding three bundles of three 20′ radials in addition to the supplied ones and it didn’t seem to help much. If I was trying to improve on the system I would try three 20m radials marked off at the 1/4 wave points for each band of interest. Just unroll the radials to the band marker. Of course this means you need over 60′ in each direction on 80m. Tuned radials have the potential to improve the performance of this system. It could be an interesting project. It also might not matter too much.
As for using a counterpoise or radials on the MPAS… one, zero, five, nine? In my experience the performance of these systems is unpredictable in the literal sense. If it gets you on the air it is working as advertised. Counterpoises in an untuned system are a funny business. When the radiator is not a resonant length I think you can do more harm than good trying to run tuned radials. I typically attach the CHA Radial and lay out about 25-35 feet of it in a convenient direction. If you are having tuning issues just change the counterpoise length/config or remove it entirely. Like a 9:1 end-fed the function of the counterpoise is debatable. It also might not have the same function in every deployment.
In a related topic, the MPAS isn’t limited to using the 17′ whip. You can attach whatever radiator you want and it will probably work. I believe the best to approach to sizing a wire radiator is to keep the suggested lengths for 9:1 un-un operation in mind. The transformer ratio might be different, but you still don’t want resonant lengths if band flexibility is on the menu.
Both matching units have loss issues that result in heat buildup. The WRC SB1000 is rated at 100W SSB, 50W CW, and 20W Digital. Similarly the CHA Hybrid-Micro is rated at 100W SSB and 50W continuous. I think a conservative approach to power output is wise here. You can smoke either device if you get too aggressive with the power. On the TIA the coil is trying to load a 102″ CB whip on 80m or 40m. This is a lot to ask and there are plenty of examples available on forums like eHam attesting to either deformation of the coil former, or outright failure when pushing the power ratings. On the Hybrid-Micro I would just assume the match at the feedpoint is bad, and that will make a lossy system worse, and that makes more heat. Heat Bad. I won’t run more than 35w in digital mode on either, and no more than 50w in SSB/CW.
I will be running a side-by-side test of the two systems soon. For now I will just give my impressions of them based on using them in the field using the same radios under similar conditions. I’ll get the bad news out of the way first: Neither is a fantastic antenna system when compared to almost anything else. Short radiators and lossy base loading are not a recipe for great antenna performance. However these antennas are not marketed as high-performance DX machines. Their calling card is portability and ease of deployment. In that respect they are both very good systems. Perceptions of on-the-air performance will have a lot to do with expectations, operating style, location, and whether making a specific contact at a specific time is essential. I have used both on POTA and POTA-style outings and they both hear much better than they get out. That’s normal. I felt like I was taking advantage of my “always loud somewhere” approach on every contact. I would be unable to work a solid 4-lander from RI (normally a given) but I might be getting 59+ reports from Kansas or Idaho. You will make contacts on either. You will make a mix of stateside and DX contacts. And no, these are not just pricey dummy loads.
The TIA got my initial performance nod based on my preference for tuned circuits over broadband transformers. But the TIA uses a whip that is half the length of the MPAS, giving up some if not all of that advantage. Also, if you run those TIA radials out to full length (recommended) you will need something like a 60-square-foot area to lay it all out in. The design is a little quirky and the user needs to be more involved with those quirks. It’s built out of hardware store parts and stainless wire. That isn’t a knock. Any ham will look at it and know that WRC puts a lot of care into their product and they are getting good value.
If you are intending to do a lot of band-hopping you will be much happier with the MPAS. Hitting “TUNE” and being ready on a new band is certainly seductive. It comes at the cost of additional system losses, but if you are making the contacts you want to make it doesn’t matter too much.
Aside from being a snap to set up in the field these antennas are providing regular HF capability to hams who may have given up on running a “real” HF antenna on their property. That’s great and the easy setup, small footprint, and low visibility are big selling factors. A concern I have expressed here and in other places is that there seems to be some confirmation bias among hams who haven’t worked with better antennas. I’ve seen excited reports of working monster Slovenian contest stations with one of these antennas and 10W, and I hate to tell you that is not a measure of *your* antenna’s performance. I’d also point out the fine work of Thomas Witherspoon, K4SWL, on his YouTube channel. He has many great real-time videos of an array of QRP rigs with different portable antenna solutions including the MPAS line. Note that he is almost exclusively calling CQ, hence pre-selecting stations that can hear him. If he was chasing stations with the MPAS he would need to take a very different approach. I don’t mention this as a negative on these antennas or the users. I mention it as a point that might be of help interpreting on-line reviews including this one.
Bugs and Observations
None of these issues are “deal-breaker” serious, but each antenna has some quirks and design issues:
I found that I needed to keep wrenches in my kit for the WRC because the 3/8″ hardware gets stuck together. It was a little annoying and I think a couple of inexpensive adjustable wrenches are a good accessory to keep with the WRC kit. Disassembly might also result in the SO-239 to 3/8 adapter coming loose on the Mega-Pod hub. I have a spare Hustler quick release that I am thinking of using to knock these issues down.
As I mentioned, the WRC Mega-Pod can be a little springy. Some care is required when deploying it, especially making sure you have slack in case of a trip or snag. The WRC whip isn’t going to take too many flops before it needs serious attention.
The MPAS Lite has fewer parts and doesn’t have much to go wrong. Still, I feel like the knob used to secure the counterpoise feels tacked on. It’s has red plastic knob and a small threaded rod which will only grab the eyelet on the CHA Radial by a corner. It doesn’t seem like it will make solid, reliable, electrical contact. It stands out mostly because everything else is so burly. Note: Unlike the SB1000 coil, the CHA Hybrid-Micro is not rated for mobile use.
As you can tell I want to review these systems for what they are. They both work as designed to allow quick setup in tight spaces and allow operation across the HF bands. They both use standard 3/8-24 hardware allowing the user to mix, match, modify, and experiment with the provided building blocks. I haven’t touched on cost but the MPAS costs more than twice the tag on the WRC. Value is so subjective that I will just say that both feel like they are priced right. Also, I don’t feel like one is a big performance winner over the other.
If I was looking for an affordable portable setup to use around the campsite, for instance, The WRC TIA is a great option. I’ve covered the setup and tuning procedures. The result is being able to work on many HF bands with no additional tuner needed.
If I had to deploy something as fast as possible, with the least hassle, the winner is the MPAS by a large margin. You will draw very little attention, take up very little space, and get on the air. Even though a transmatch is required it doesn’t seem to be much of a hurdle. I used several matching units, including the MFJ-901, and they all worked just fine. You can also load a long wire, end-fed inverted vee, vertical wire… so the system is more flexible than the WRC.
I hope this post has been helpful. I have enjoyed using these systems, and can see why they maintain their popularity. As long as your expectations aren’t for some miracle system that gets big antenna performance in a small package then you can expect to get a lot of enjoyment out of either.
Comments Off on Lightweight Antenna Roundup 2 – Chameleon MPAS Lite v Wolf River Coils SB1000 TIA
The reason why I would bother with this topic is twofold: One: I think better antenna systems are actually better; and Two: Technical concepts are central to amateur radio and should be understood and employed as often as possible. I’m discussing these antenna concepts in simple terms in the interest of keeping it accessible. Hopefully it leads to some further investigation and a different way to think about antenna systems.
WHAT IS RESONANT?
In the Venn Diagram world it can be said: Not all 50 Ohm feedpoints are resonant, and not all resonant radiators present 50 Ohm feedpoints. I have seen much confusion between “resonance” and “impedance match” on internet forums/platforms/videos. This what drove me to churn out this post.
Resonance in an RF radiator actually does make a difference. I’m a fan of Hemholtz and resonance is a real thing. When I assess a antenna design I start at the radiating element or elements. If that element is not a known and desirable harmonic relation to the fundamental frequency of interest I consider it a non-resonant design. If there is a matching unit connected to a non-resonant radiator I consider it a tuned circuit. When the goal is efficient and predictable RF radiation you have resonant radiators, and then everything else.
Recently there has been an explosion in the use of end-fed wire antennas. I use a few of them and they are an easy way to get on the air, usually on multiple bands. I have made plenty of contacts on these antennas, but at no point was I under an illusion that I was using an efficient antenna system. The now ubiquitous End Fed Half Wave is a strange bird, It utilizes a half wave radiator with a feedpoint impedance of about 3000 ohms, and is operated without a traditional ground plane or counterpoise. The high impedance feedpoint is matched to somewhere near 50 ohms with a 49:1 or similar toroidal un-un transformer. That is not a recipe for efficiency. The power ratings on the matching transformers tell you all you need to know: These matching units get hot, and that heat is your RF not making it out into the world.
That’s not to say it’s a bad design. It solves a few of the issues that keep many hams from being able to get on HF. You can hang it from a single support, as opposed to needing two or three for a horizontal dipole. It’s also easy to erect on demand, which is great for hams who want to operate portable stations or if they have a compromised (small, HOA, etc…) QTH. I use a 12m Spiderpole and a PAR Trail Friendly when Inwant to get on the air quickly. Also, thanks to the magic of harmonic resonance, it is common to find a match on more than just the fundamental frequency.
Another common design is the random length end fed, usually known by the 9:1 un-un transformer used to feed the non-resonant radiator. The trick here is to find a radiator length that is not resonant on any band you want to work. The hope, and I do mean hope, is that the feedpoint impedance will be somewhere in the 200-800 ohm range, where it can be matched to 50 ohms using a second matching device. Again it has the advantages of ease of setup and multiband capability. The tradeoff is even steeper than the HWEF. This design is force-feeding a non-resonant radiator, has an even lossier (IMO) un-un, and requires a second matching device to get all the way to 50-ohms.
A problem both designs share is the difficulty in modeling a radiation pattern. Even with many analyses and many users over many years nobody seems to be able to say much beyond “omnidirectional”. That’s not too helpful. The main issue in modeling these systems is properly representing the ground/counterpoise. Most installations (mine included) require a common mode choke (CMC) near the radio end of the coax to keep RF from energizing the radio’s earth ground. How efficient does that sound? Do we have any idea what these antennas are actually doing wit the RF that makes it out into the world? Empirically I think we do. Scientifically, predictably, I don’t think we have a good handle on it.
So, how important is the efficiency of a transmitting antenna?
Hams with even some basic experience on HF know that you can make contacts on almost anything. Take a simple transmatch design like the MFJ-901, hook it to a rain gutter, and make a contact. Do we know anything about the radiation pattern, efficiency, or bandwidth? No. We are just interested in forcing something conductive to radiate RF, and hope for the best. The magic of radio waves takes care of the rest. If enough of your RF makes it out in the correct direction you will make a contact. Your signal might even be strong! But this is where it helps to be aware of confirmation bias. The science of radio communications involves being able to control where your signal is going, and control the system design to connect you with the intended destination. Having made some contacts is almost inevitable. Making the contacts you want to make when you want to make them is where the game gets interesting.
In the food-chain of antenna designs these lossy designs are somewhere in the “krill zone”. A good efficient design, properly installed is somewhere in the “cordata zone”, and a very efficient directional design mounted high and in the clear with directional control is “blue whale” territory. At some point the operator is limited by their Effective Radiated Power (ERP) and the weakening of the transmitted signal with the square of the distance from the antenna. Using 10-30% of your RF to warm a toroid is cutting in to your effective range. Every system has limitations, but when running 10, 30, 50 watts at the finals, I feel that making the most of it is important. Every improvement in efficiency and pattern control brings you up another link in the radio food chain.
Certainly the parallel popularity of end-fed wires and weak-signal digital modes, best represented by FT8, are not coincidental. FT8 allows working at lower signal to noise ratios which is like getting that lost RF back when compared to working SSB or RTTY. More efficient antennas are always an improvement, but an entry-level HF rig, a HWEF, and WSJT-X is a great path of entry to the HF bands. I’ve gone on about this earlier, but there is nothing in-stone about needing to start with CW or SSB. Hams can get on the air, interact with DX, and get some good contacts in the log. I see nothing wrong with that.
Compact, Broadband, Efficient: Pick Two
In the HWEF and 9:1 design cases the user is giving up efficiency for a more compact, more broad-banded (lower Q) device.
The HWEF, thanks to its resonant radiator, is somewhat more efficient, but the price is being paid for getting wide frequency coverage on a single radiator. Some designs find ways to better balance the equation by sacrificing some bandwidth and band flexibility to increase efficiency. One QRP design I use is the PAR 102040 Trail Friendly. This design uses three techniques to get a three-band end-fed vertical into a single 41′ wire radiator package. Trick 1: It uses a trap to isolate the 20m half wave element from the 40M extension. Trick 2: It uses the characteristic electrical lengthening effect of the trap to keep the 40m extension (and overall length) shorter than a simple 40m half wave radiator. Trick 3: using the second harmonic of 20m to realize some usable bandwidth on 10m. The transformer is pretty much handling the design goal of representing a 3000 ohm feedpoint as a 50 ohm load to the rig. No additional trans match is needed if you have trimmed the 40m extension properly and are ok with the tuning points. It isn’t brilliantly efficient, but it’s not horrible.
Chameleon MPAS Lite – Mini Review:
In early 2021 I picked up that Chameleon MPAS Lite and wanted to give it a run as a portable antenna system for POTA. This unit is extremely compact and is comprised of a ground spike, a un-un, a heavy duty stainless whip and 65’ of wire to use as a counterpoise. With the engineering triangle in mind I knew I was giving up a lot of efficiency for a very compact, very broadband system. And that’s what I got. It works well enough, especially if you are calling CQ and self-selecting stations who can hear you. I found that replying to anything but the loudest stations was a bad recipe for success. In a Chameleon forum I made the comment that these antennas aren’t good DX setups. I stand by that. It isn’t that you won’t work any DX, you would just work more DX more easily with a better DX design. For mid-range and NVIS work I think it is a solid solution. That assumes you are able to make the contacts you need to make. Also, watch the power rating because the un-un will get warm, and will fail under excessive power and duty cycle.
The MPAS system uses a 5:1 un-un design to feed anything from their very nice stainless whip, MIL Whip system, a longwire, or whatever conductive item you decide to use. The 5:1 takes a conservative approach to the non-resonant radiator problem, and a second transmatch (internal or external unit) is required unless you get lucky and dial in a 250 Ohm (or 10!) feedpoint impedance for the Un-Un. Chameleon publishes a perfect omnidirectional pattern for their antennas. That’s a good assumption for the operator since non-resonant systems are difficult to model accurately. Just assume your RF is going in all directions equally. Might as well! In practice I have made contacts and successfully activated a few parks using the MPAS Lite. Chameleon builds a beautiful and rugged product, and supports their users well. II feel like it is a good system and the user will get the best out of it by realizing it’s strengths and weaknesses.
One concern I have from following a few antenna forums, including a Chameleon product support forum, is the number of users claiming to have “resonant” solutions. An actual resonant radiator would provide a terrible match with a 5:1 un-un. What users are doing is finding a radiator length that presents a 1:5 feedpoint impedance to the CHA transformer so the radio sees 50 ohms(ish). That approach may be usable on that band with no additional matching, but is likely to be worse on other bands.
Another constant question on these forums regards radials and counterpoises. Strangely the solutions discussed are often none, one, or several short radials. All of these are poor solutions. However, when the central design concept is to never be resonant, not require radials, and use almost anything as a radiator, I don’t know what a good solution looks like. The Chameleon counterpoise kit is 65′ of very hunky insulated wire and can help you play with the counterpoise dimensions/layout and maybe help in finding a match. That said I feel like users are trying resonant counterpoise lengths and I think that does more harm than good. With a single counterpoise, stick to the game plan. Why make the two impedances different?
The Chameleon 50′ RG-58-ish feedline with a ferrite bead choke on one end is a decent way to control the stray RF. And it is necessary. Every time I have used it I had to control RF that wanted to energize the radio’s earth ground.
The best application I have seen for these matching units is Chameleon’s own Tactical Delta Loop which uses the CHA as the feedpoint in a system where 5:1 isn’t a bad design value. I will be cobbling a test setup soon out of various Chameleon and Wolf River parts.
If it sounds like I am down on end-fed designs, I’m not. They have a proven track record and get hams on the air. What I would like to get across is that I hope ops get some time on other designs. Building a nice 1/4 wave vertical over a good set of radials is very easy and cheap. Think of a it as a single-band DX Commander style build. I think it is worth the time and small expense to see how a resonant design works and maybe make a few on-air comparisons.
If you stuck with this post I owe you a pint. I don’t write these to be concise blurbs. I like to compose my thoughts on these topics and I figure sharing it is part of the experience. Let me know what you think! Reply on the blog, or look me up on QRZ and drop me an email.
Get on the air, and always have fun. 73, Pete N1QDQ