Your Pro Citizen Newsletter 68: HF Radio Antenna Fail; upcoming CM-7 release

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How did this happen?

I got this idea from a youtube video or two, the concept was intriguing. The concept is to use a chalk line (the reel component of it) to build an adjustable antenna that can be reeled in or out to resonate on any HF band. Sounded great! As many of you guys know I have a hate/hate relationship with radio, especially HF. The hobby component of lugging around a picnic table full of radio centric gear and octopus cables to call strangers with acerbic dispositions just to speed talk a string of verbiage and check off a journal entry is a root canal for me. But I damn sure understand and appreciate the capability it can bring to the readiness community. And I have utmost respect for the guys who understand radio. At a minimum those of us in the Pro Citizen community should have simple mid range HF radio capability. To accomplish this under our anticipated conditions we require a compact, easy to set up and tear down HF antenna system. I wanted something as small and versatile as I could get, this chalk line antenna setup looked like it would be not just “A” way, but a very good way. Gather around your Pro Citizen coffee cup my friend and I’ll tell you how it went.

But first - why HF?

I rarely write about radio stuff since it is not in my primary expertise wheelhouse. I have been a “General” ham ticket holder for a few years but the only thing that really means is I could study the questions for a test. I have a very basic understanding of how radio works, but I am an expert at using the capability radio provides to lead formations and operations. The technical side of ham radio HF I am average - but working to improve that. I wanted to give you an idea of my background and thinking on this, from this typical dude perspective. I am not our group’s RTO, nor do I ever want to be. But sometimes we can get pushed into a requirement where we will need the tools and knowledge to use them. As distasteful as it may be for you if you aren’t a “radio guy” you need to become one - at least to gain the surface level knowledge of how radio works. When supporting disaster response operations, the regional communications an HF system provides is invaluable. You and your group might be loading up in your truck soon to go help out a disaster six hours away. What capability are you really bringing to the event? I’ve said it before when it comes to disaster response - everybody has a chainsaw. You arrive with a chainsaw and an axe…it isn’t a big deal they are a dime a dozen. But if you show up with a comms platform (even a small one) you can make a real difference in short order. We saw this during the Helene response. There was limited comms in or out of the disaster area in the first few weeks; information was spotty at best. Just finding out what routes were open was painful. That disaster really gave the “that will never happen in today’s modern connected world!” folks a reality check. Infrastructure can be disrupted (or even destroyed) and eliminate the ability to communicate across a large area. There were radio operators who were able to help get the western NC folks help they needed, but there were not enough of them. If you are able to power it and know what you are doing an HF radio transmission can still get out when communication systems disappear. During events like Helene being able to talk to a station 100 miles outside the disaster zone is a lifesaver. That far station can receive radio traffic or digital files and then relay information on the unimpacted networks to get relief assets moving. HF can be the first link in this communications chain. The freebanded Baofeng handhelds the readiness community loves become even more limited when repeaters aren’t getting power (or the tower has disappeared altogether in a landslide). If the area has severely restricted radio lines of sight due to terrain or buildings the VHF/UHF capability is cut down still more. Even if you live in the flat parts of the desert southwest or the Kansas plains the higher band handheld systems are still anemic compared to the HF bands. Not to mention being able to push out actual data files.

The digital file pipeline is a foggy realm I haven’t walked into yet…but I will eventually. My radio guru is doing some heavy lifting to help me understand all this HF madness, please pray for him as he brings me into the world of FT8. I will write about that eventually, maybe I can even convince him to write the article up for us. In the meantime, go check out Wyoming Survival’s youtube channel and check out his HF comms content. If you are not a “ham guy” you may be surprised what can be sent without any communications infrastructure over an HF radio.

To be crystal clear (< - our three old school ham readers just laughed at this) I do not think our efforts should be focused on long range (DX) communications other than using it to learn radio capabilities. The sweet spot for us is regional and maybe (big maybe) reaching coast to coast. We should focus on reaching from just beyond VHF range to a couple of states over; sending a signal nearly vertical (NVIS) to bounce off the ionosphere and return to earth the next state over is what we want out of HF. Talking to a station on Howland Island in the Pacific may be mildly interesting, but for us it serves no practical purpose. We 100 percent need a low power consuming HF capability in our groups that lets us talk two states over. HTs are great and necessary, but I am of the opinion we must have both capabilities in our communities.

The Antenna

We need a compact, easy to set up antenna system. Our use case is not grandpa’s backyard ham shack where he sneaks out to drink PBR and hide from grandma. We need lean and mean, high speed, low drag setup. No poles, masts, rats’ nests of cables in our RTO’s ruck. The challenge is finding an antenna that works across multiple HF bands; a single antenna that works “good enough” across our group’s typical frequencies/bands. For us that is probably something that hits 20 to 80 meters. Just that statement alone warrants pages of explanation and technical details, but for our purposes we can just roll with the band assumption. Ham radio readers you guys just bite your lip and cool your keyboard for a second, this is written for average dudes who don’t have a lot of radio experience or are newer folks looking to build capabilities. We think we need 20 to 80 meter coverage in one antenna; something that is light and compact / manageable in the field - a good place to start. Some in the community will have higher power portable radios (100 watts) and have to account for that, but for my system I am in the 20 watt max category so I can use an antenna that somewhat less power sensitive.

The concept for the project was to use a chalk line reel with antenna wire and run it as an end fed half wave - adjusting the length to be resonant on the primary bands we think we will use (20,40, 80). The user could reel it out to the specified length for the desired resonant frequency and Shazam…talking to everybody. A quick overview for non ham / new radio folks: HF radio (all radio) frequencies have lengths associated with them; the length of the waves is how they are measured. One cycle measurement is a wavelength, and antennas are measured in full, half, quarter wave and so on. Your HT antenna is probably a quarter wave meaning the physical length of the antenna is 25 percent of the wavelength for the frequency it uses. Hang on my ham dudes, give me a minute to clarify, stop typing that email to me. This is always a compromise for antennas that cover full or multiple bands, that 70cm and 2m handheld radio has to find some middle ground. It has to be built so it covers as many frequencies as possible, a compromise as it were. We have to do that with the HF antenna as well, but the lengths are much greater (longer wavelengths compared to VHF and UHF). As an example, the 80 meter band has 80 meter long waves and 20 meter band’s are 20 meters long (plus or minus depending on specific frequency of course). This means a 20 meter full wave antenna is 20 meters long and a half wave (which we prefer for HF use) is 10 meters. Since we went to the moon and use imperial measurements let’s call 10 meters 32.808 feet. Same for 80 meters which equates to roughly 131 feet for a half wave piece of wire. There is math to find the center of the band and optimize for that frequency etc etc but I want to keep this simple for my own sanity this morning. So at 131 feet for 80 meters (lets call it 125 feet for center of the band) that is a heck of a section of wire to stuff in your rucksack. By the way if you can’t use the same antenna you also need another separate 32 foot piece of wire for 20 meters. And a 61 foot piece for 40 meters. You get the point. We need a way to get as much utility out of one piece of wire as we can. A quick aside there are ways of doing this by using a non-resonant antenna, tuners, and all kinds of other sorcery, but we will talk about that another time. The goal for this specific antenna is to have a resonant length for each desired band achieved by reeling in or out. For the readiness community the appeal of having an antenna cover multiple bands is not one of convenience, it is a necessity. This is all a gross oversimplification of how this works, but hopefully it paints the picture of what we need from an HF antenna system.

How I built it

The components for the build included a chalk reel, 30lb copper wire, coax feed line, an insulator, and a 9:1 UNUN (a transformer that matches an unbalanced antenna to a feedline). I won’t delve into the construction details for reasons you will read below. Bottom line is it would be a waste of time for me to write it up since it performed so poorly and is a non-solution (in my limited experience building it).

I knew I needed at least 131 feet to cover 80 meters (half wave) so the reel had to accommodate that length (it was not an issue). A quick browse through amazon and I had the components. I had a 9:1 leftover from an end fed I had built a while back, so I ended up using it. I purchased a 49:1 “kit” as well, but that was a disaster, so I just stuck with the one I had. Quick aside, those kits are great if you are a ham hobby guy, but don’t waste your time or money if not. They are an exercise in frustration. I even got called the “lowest common denominator” when I emailed the company for assistance with building it. And ham guys wonder why there is hesitance to partake in the hobby. Anyway…I got the reel assembled and all set up, off to measure and find out where the center of the 20, 40, 60, and 80m bands fell (physically first and then electronically with a meter). Resonance may not be exactly at the center frequency, but this was a big moving pieces kinda’ project. I was always taught to get 2 or lower on SWR for any antenna to protect the radio from damage, for resonant lengths that should be easily achievable even without a tuner. Here is where this fell apart.

Test Runs

Based on the videos I had seen of these and my (limited amateur) radio knowledge I knew I would have to get close to resonance (the point where the antenna physically matches the frequency) by physical measurement as I reeled it out to each band. I started with 20 meters or 29 ish feet to be roughly center of the 40 meter band at a half wave. Too easy. Set the length and confidently strolled back to check the SWR meter fully expecting a 1.5 or at worst a 2. 5.6? Wow. That is rough. I knew it should be a lot closer, but I also knew these setups were an exercise in making an educated best guess before getting them dialed in. Just like adjusting artillery fire I made a bold first adjustment, five feet longer to see what happened to SWR (it was flatlines across the entire band so I had no indication of which way to go). Run back to the meter with child like enthusiasm. Nope. Wrong way. Lets try10 feet shorter than that. Nope. Ok lets try another band. All the way out to 80 meter band (125 feet half wave roughly center band) for the same process. Longer sprint back to read the SWR meter this time but it was some additional Rule 1 training so all good. Same results, big honkin’ 5 plus SWR. Ok doggone it, let’s set the meter to check across all the bands from 20 to 60 meters and see how she looks. Check this out:

It is backwards from where it should be. The high SWR showing up where the antenna should have been resonant and a good SWR at 20 meters (the math doesn’t math for quarter/half/full either). This was a half wave for 60 meters (close to resonant measurement for 5.35MHz) should have been close to 1 or at least under 2. I chased this over two days and just couldn’t get it to dial in across any band. My radio mentor couldn’t figure it out either (he was at a disadvantage though only doing this via text messages and photos). Each time I tried it I would get a different result, and it was beyond unstable. I was able to get a 2:1 briefly on 20 and 40 but it was not repeatable and would be back up in the 4-5 range. Could a tuner overcome the SWR? Maybe. But this is an inherently compromised system as it is, I would not be confident due to the tolerance stacking on something like this. I’ve “seen” (youtube) guys make this work, but for me I just couldn’t get the result I wanted even when I tried to make it work on a single band. The thing I can compare it to was watching (and eventually correcting) dudes trying to zero a carbine with a bent front sight post. The group looks good, but the first adjustment throws it out of the black in a wild direction. This was the same idea, way too much chasing SWR and resonance for my purposes in this antenna. The antenna (not the tuner) is supposed to do the work for this antenna, and it just wouldn’t cooperate. Again, this is a sample size of 1 and an amateur making a run at it, so take it as such.

Summary. You may get this to work for you, this may an anomaly or operator error. I always want to show you guys the fails that come with the successes along the way so you know downside of a particular good idea. The requirement still stands to have a compact, easy to deploy 20-80 meter solution. But for me this ain’t it. I’m going back to a non-resonant EFHW for now, hopefully one of you guys can figure this one out for us. I’m going to give this setup to my radio mentor and let him pull his hair out over it. You guys watch, I bet he will dial it in with no problem…but I’m OK with that.

New release late May!

Meet the CM-7, the Minuteman Recon Handbook. The CM-7 bridges the information between the CM-2 Recon Manual and the CM-6 Citizen Ranger Handbook. The 7 is the essentially the Ranger Handbook for Recon, with everything adapted and tailored for the Pro Citizen community at the squad and small team level; the size of organizations most of us are part of. More details to follow, it will be finished in the next few weeks just in time for your team’s summer field training exercises (FTX).

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