Looking back it has been April since my last post. A lot has happened during the intervening five months. As some of you may know, we lost my father-in-law in May. Prior to that we had been helping him deal with a number of health issues that consumed a majority of our time. Since his passing we have the inevitable task of now dealing with his estate. Fortunately it’s not a large or complex one, but the wheels of government turn slower than ever so we are in the waiting game while we work to get his home ready for sale.
Being a HAM operator, and a member of the local ARES group, I want to take a quick moment to remind everyone to keep our fellow hams in Florida and the Carolinas in our prayers as they deal with the issues brought about by hurricane Ian. The pictures and video coming out of south Florida show massive damage and disruption to what were once beautiful sea side resorts and destinations. If you are able to help in the relief and recovery efforts, please do. Fortunately, here in Virginia we are only likely to get a lot of rain and a little wind, though that could change. Interestingly enough, as I’m sitting here writing this post, my power just cycled, so who knows.
It does mean that I’m working from home today so maybe I’ll have some time to write a little more about some of the projects I’ve slowly been working on. One of those projects, that I have just been able to complete, is my new 150AH battery pack. I will be working on the write up and will have it out to the blog in the next week or so. Till then, be safe and keep building.
When we left GB Part 2, I talked about the fact that things didn’t always go as expected during either the GB1 or GB2 builds and that we would take a look at some of the specifics in this 3rd, and hopefully final, post for this series. I apologize ahead of time that there are no pictures in this installment, mainly due to these ideas having been thought of in hindsight and no pictures documented the failures. Also, though it might seem strange, I have no problem discussing issues and mistakes made during the development or building of any of my projects. As a nuclear engineer and process analyst by trade, it is my day job to objectively review trends and performance data looking for problems and looking for the lessons learned in them. So this is familiar territory, and any DIYer worth his or her salt should embrace learning lessons from failure, whether it’s theirs or someone else’s. I believe that it was Elenore Roosevelt who once said,
“Life’s not about expecting, hoping and wishing. It’s about doing, being and becoming. It’s about learning from the mistakes of others. You can’t live long enough to make them all yourself.”
I can’t agree more. If you never try anything you will never make a mistake, however, you’ll never get anything done either! So with those thoughts in mind, lets take a look at some of the issues I encountered in both of the GB builds.
Issue #1 – Weight
At the top of the list is weight. Although I have never weighed either GB I know that their initial versions were both very heavy. Lets take GB1 for instance:
In its initial version, GB1 had 3 metal shelves, a battery pack, and internal power supply. This made for a lot of extra weight and complicated the wiring. On further evaluation I had to resolve myself to the fact that something would need to be eliminated in order to achieve a reasonable level of portability. In the end I was able to reorganize the contents, shed the battery but keep the power supply, and generally simplify the power side wiring.
One thing that allowed me the ability to remove the battery without significant loss of capability was my adoption and building of external, portable battery packs. These will be covered in future posts. I was also able to sit back and do a “clean sheet” reconstruct of the box to make better use of the space available, but keep all four radios.
GB2 was also plagued by battery weight. The internal battery also had the added detractor of not having a significant amount of available power to justify its continued use. So in the version 2 rebuild I removed it and used that space to uncrowd the power and control wiring.
Lesson Learned #1 – Weight is a significant factor to address when you are building something that is intended to be portable, and by that I mean that you can move it yourself without a lot of assistance.
Issue #2 – Building Materials
In the quest to build GB2, I ran into issues of how to mount the equipment into the Apache 4800 case so they wouldn’t move around and become damaged. There was also the initial goal of having the case be somewhat weather tight. To be honest, these cases are great, for their price, but I would honestly never expect them to be watertight in any manner. That’s not a knock on the item or brand, just a simple expectation. If I really wanted watertight, I would spend the money on the Pelican brand, buy the related accessories for mounting the gear in one, and call it a day. But as I’ve said before, I’m cheap and this case met my needs.
But that still left me with the need to mount the gear. Enter, the drill and cap screws. Most everything inside that is heavy (like the radio bodies) is bolted into the case using cap screws, through holes drilled into the case. Really not a big deal, as long as you don’t make a mistake and drill a hole in the wrong location. I think I did that twice (remember the battery in version 1?). The repair, if you want to seal it up can either be a glue/epoxy of some sort, or heating up and sealing the hole with an old soldering iron. Honestly, I did neither. I fortunately was able to reuse those holes to mount the power distribution strip.
Another point here is that, in most cases, if you still need the case to be somewhat water tight, you can easily seal the screw holes with a sealant such as silicone. Also, by taking care to drill the holes slightly undersized in the plastic, they will almost self-seal due to having to virtually thread the screws into the holes.
Lesson Learned #2a – Take care when laying out holes to be drilled in GB cases. Though not usually a major issue or problem if you get it wrong, it does ding the look and our egos just a little.
In addition to the heavy gear, I also bolted 3/8″ aluminum angle around the perimeter of the case to allow for mounting the front panel holding the computer screen. I was able to drill and tap the aluminum for cap screws to hold the panel in place and allow for easy removal if required. That leads me to the next problem in this issue – brittleness.
One problem when working with build materials is the disparity of characteristics in a particular material. Take the front panel of GB2.
In version 1, this panel was cut from 1/4″ lauan plywood. A good strong material that cuts well and can be fabricated into most any part for a build such as this. However, it’s also flexible. So flexible, in fact, that I was afraid the flexing would result in a damaged screen. It also left sawdust residue where parts and cables rubbed against access holes. So in version 2 I opted for 1/4″ Lexan. This material is super strong, easily machined, and though flexible, not as much as the plywood within the dimensions of the box. All was great until the mounting hole in the upper left corner was drilled slightly out of alignment. In the struggle to get all of the screws to align and tighten down, this corner ended up cracking. Not the end of the world, but disappointing. Solution, epoxy the broken part back on, redrill the hole, and reinstall without the drama. Had this been the plywood panel, the flexibility would have allowed the misalignment with little grief.
Lesson Learned #2b – Make sure you understand and evaluate all of the characteristics of the materials you plan to use when building a project. Strength, flexibility, brittleness, UV resistance, to name a few, can all have an impact on the final project and its ability to meet your established goals.
Issue #3 – The Raspberry Pi In Portable Ops
It is no question that the Single Board Computer (SBC) has revolutionized the DIY/Maker landscape. Whether it’s an Arduino, Odroid, or Raspberry Pi, the fact that a significant amount of computing power can be housed on a small circuit board, smaller than the average cell phone, is amazing. The uses for SBCs include remote sensor and data gathering, robotics, automation, and of course portable computing. It’s in that vein that we employ a Raspberry Pi4 in GB1 and a Raspberry Pi400 in GB2.
In their basic form, each one uses a small Secure Digital, normally known as an SD card, to store not only the operating system, which is usually a smaller form of the linux operating system, but other files as well. These can include equipment manuals, emails, and documents. Add to this the available sizes of these small cards (128Gb+) and the capabilities begin to multiply significantly.
However, there is a drawback to this arrangement. SD cards have a limited number of writes and they are fragile if not handled properly. There is also the issue of wear and tear on the SD Card slot of the pi, and without a regular means of backing up the card, a bad card means total loss of your data and having to rebuild the operating system and programs from scratch. A process that can take upwards of 4-5 hours at least, depending on the number of programs installed and the data involved.
One solution or alternative that the generation 4 of Raspberry Pi readily supports is booting from an external USB or SS drive. This is a great solution and solves many of the problems presented by the little SD card. When coupled with the USB3 ports on the RPi4 series, the data throughput is not unlike that of a normal linux computer. Great! you might say. Problem solved! Well, maybe… It depends.
You see, there is a little dark secret associated with the USB3 port. I won’t get too far into the weeds on this here, but if you want to look into the gory details you can follow this link to an Intel article on the RFI issues that USB3 can cause. In a nutshell, USB3 is spread spectrum and causes significant interference in the 2.4Ghz band if the ports and cables are not properly shielded. You know, the band where wireless mice, keyboards, wifi, etc., operate? That can present a problem if you employ these devices in your build. It also interferes with GPS dongles that plug into USB, like the ones I use for obtaining grid square info in the Conky program. The solution I’ve implemented is that I purposely plug USB3 devices into the USB2 ports and non-USB3 devices into the USB3 ports. I know it seems counterintuitive but as long as the port doesn’t register a USB3 compatible device it won’t revert to spread spectrum, thus no RFI.
So in my GBs I still use a SD card in the GB1 pi and I use a 480Gb SSD in GB2. Overall both work great, and at some point I’ll break down and get a SSD for GB1 to keep from having to backup the SD card all the time.
Lesson Learned #3 – Understand the limitations and potential RFI issues related to SBCs, especially the Raspberry Pi 4 versions with USB3. Also, this is one area where spending a little money is likely a good plan when it comes to cables used with USB3 to insure they are properly built and shielded to minimize the RFI. If your plans do not include the use of wireless mice, keyboards, or GPS dongles, then the spread spectrum RFI from USB3 may not be an issue for you. Best advice, experiment and see how your system works and address the issues as you find them. However, do yourself a favor and do your testing at home so you’re prepared when you go portable with your GB.
Well the truth is I could go on for pages relating issues related to building these GBs but I think I’ve hit the highlights that I wanted to cover. As always, if you have a question about how these GBs were built or questions about an issue you’re experiencing drop me a line in the comments and I’ll get back to you as soon as I can.
Welcome back to my Go Box (GB) series. I’m not sure if you can really call two a series, but since this will likely go to three, I think we’re good, so here we go. In part one, we looked at what you might call a more traditional GB, similar to the majority of examples I saw online when I was doing my research to build my own. Now I don’t mean traditional in a negative sense. These rigs are functional, pretty sturdy, and can take a lot of abuse during transport and storage. I really like mine and it works extremely well for its intended purpose. However, I wanted to build one that was a little different and I took my inspiration from a REDDIT forum on cyberdecks that you can check out here. Also, in order to differentiate between the two go boxes I will continue the naming convention from Part 1 and refer to them as GB1 for the one we covered in the first part, and GB2 for the one we will be discussing here.
What is a CDK? It seems they originated in the online gaming world and essentially are custom, portable computing devices built to meet the needs of their users. Be that hacking, non-sanctioned access, etc. Not that I advocate any of those or related activities. Okay, so what does that have to do with ham radio? Well, as I was going down this rabbit hole of exploration, I got to thinking about my first go box build with the integration of a raspberry pi as a sort of system controller. Additionally, the usefulness of being able to have a lot of information at my fingertips in the form of manuals and radio support data has proven beneficial to support a prolonged deployment or extended time away from the benefit of the internet.
In fact that idea led me to several builds that were focused on what is nominally called a “Crash Recovery Device” or CRD (you can see an example here). This is a specific type of CDK that combines extreme nerdism, with an apocalyptic bent, to build a device that can contain a significant amount of data and human knowledge in case the world comes to an end and we have to try and survive from scratch. Should we really end up in a SHTF situation, the internet and all of our normal information sources may go the way of the dodo, or at least be unavailable for a long period of time. Okay not exactly an uplifting topic, but the geeky side really appeals to the DIY Ham! (Did you know that you can fit the totality of the English version of Wikipedia, including pictures, in less than 100Gb? That is absolutely cool!)
So I got to thinking, what if I built a CDK/CRD, that also had ham radio communications capability, and that fit in a single, self-contained, sealed case? After a lot of drawings, figuring, and much head scratching, GB2 was born. My initial goals for this were:
HF through UHF capability
Voice and Digital modes, to include packet, simultaneously
Raspberry Pi 4 or better
100G+ storage to store Wikipedia and anything else I might want when everything goes South
Built in screen, keyboard, and mouse/trackpad
Weather tight (this one had a few compromises due to the need for heat dissipation)
Self-powered (this one didn’t pan out either due to weight vs operating longevity and required a rebuild into the version 2 shown in this article)
Carry in one hand, since as a rack, GB1 really needs two hands to move around
With these goals in mind I set out to assemble the necessary gear on a limited budget.
I was never going to be able to justify buying new radios for this box so I waited until I could go to my next hamfest to see what deals I could swing. Well, as it so happened, our local hamfest organization finally was able to put on a limited event in the fall of 2021 (thank you COVID) and though it was a small event, I thought it was a great success. Of course I came away with a very high opinion because I scored two significant deals on the two used radios I eventually would put into GB2:
Even though I did have to replace the display in the 857, due to the dreaded zebra stripe syndrome, the overall cost was still significantly below what I would have had to pay on Ebay (if I could even find one there).
The next task was to locate a screen. As you saw in the first installment, I salvaged a screen from a dead laptop. If you followed the link to DIY Perks, you also learned that I would need to buy an interface card based on the model of the screen. In GB1, the screen is mounted inside the front cover along with the interface card and the control board. So for GB2, I decided to do something similar and happened to have another laptop that had given up the ghost, but had a good screen. So for GB2 the screen was mounted on the front plate and the interface card attached to the back side. With the screen element solved, I turned my attention to how I was going to mount it.
You see at about this time I was also looking for the case to house this build and had finally decided on a “Pelican Like” knock off case from Harbor Freight. If you’ve taken the time to follow the links above to any of the Youtube videos on CDKs/CRDs you likely noticed this type of case being used in their builds. However, since I was incorporating a laptop screen, which is bigger than the 7” pi screens most of them use, and I was installing mobile ham radios in the case, I needed something just a little bit bigger and settled on the Apache 4800 case.
After doing some modeling in Sketch-up I figured out that I could get all of this gear into the volume of the case, I just had to be creative about it. As shown in the CRD video, the bulk of the equipment is housed in the larger portion of the case, what would normally be the part facing up when open. That also means the “lid” is where the keyboard rests. This arrangement allows for a more comfortable operating position. This is how I chose to build mine as well.
Since I had great success using a Raspberry Pi 4 (RPi4) in GB1, I wanted to do the same in GB2. In version one of GB2 I stole the RPi4 from GB1 initially to evaluate mounting, case, etc. to determine what I would get as a final version for GB2. Well, things worked well and I was able to find a keyboard that fit the lid and also have a place to store the mouse and a few other items (like mics for the radios), but the RPi4 itself was buried inside the upper case and not really accessible for any type of maintenance or changes. Also the lid arrangement just seemed clunky and using the mouse was a headache because it had to be on its own pad outside the lid. Not to mention, the price of RPi4’s was steadily climbing. Enter the RPi400.
If you’ve not seen one of these little beauties, they are the cat’s meow. Basically it’s a RPi4/4Gb built into a keyboard. All the ports are on the back side and it has a massive heatsink that keeps it cool as a cucumber under the most strenuous loads. It’s also small enough to add a trackpad to the right of it, in the lid, so all of the control functions are contained within the confines of the box. This was the final arrangement I settled on.
Since we are talking about the lid section, lets cover what’s there. In addition to the RPi400 and trackpad, there are:
A pair of 2” speakers, one for the audio of each radio
Power switch for the RPi400
480Gb SSD plugged into the RPi400 that boots it and stores all files. There is no SD card. Also, this is plugged into a USB2 vice USB3 port. There is a specific reason for this, that I’ll cover in part 3, and has to do with the spurious RFI associated with USB3 and its impact on USB mice and GPS dongles
Support structure to elevate the pi and house the speakers and cabling
Adjustable thermostat for the internal case fans that keep the radio bodies cool during extended operations
Recesses for the mics to sit when packed away
Main/Upper Case – Front Cover Plate
The bulk of the gear is housed in the upper case. The front cover plate holds the following:
Salvaged Laptop Screen
Control panel for screen
FT-857D radio head
FTM-350 radio head
USB power jacks and 12v jack
HDMI extension jack (remember the pi has two ports, one goes to the built-in screen and the other is accessible here
USB extension ports (connects to an internal USB hub)
Power switches for the screen and accessory power
The front cover is ¼” thick lexan that has been drilled and painted to match the overall look of the build. It is suspended in the box with 3/8” aluminum angle drilled and tapped for black hex head cap screws to give it a military look.
Main/Upper Case – Inside
Inside the box is where all the fun is. In the initial version of GB2 I included an 8AH battery built from 38120 Headway cells. It worked great, but added significant weight to the case and with a limited operating envelope (limited power) I felt that it was better to have the power supply (battery or AC) housed outside the GB for more flexibility. The upside, other than the weight reduction, was that I had more room to spread a few things out and neaten up the arrangement and wiring. So here is the list of the internal items:
FT-857D radio body
FTM-350 radio body
CAT to USB cables for both radios
50Amp Anderson panel mount connector
Power distribution terminals
RF panel jacks (SO-239 pass throughs)
Main/Upper Case – Outside
The outside of the case, for the most part, doesn’t give much of a clue as to what’s contained inside. As we will see below, the initial goal of maintaining a weather tight package would be compromised by the need for ventilation in the upper case. As you can see in the picture to the right, I also chose to simply bolt straight through the case when mounting various items on the inside.
I have seen quite a few articles and videos that discuss the desire to maintain a storage case “water tight” or some such condition, and on a certain level, depending on your needs, that’s a valid concern. For me, with the operational goals I set for this box, that was not a significant concern.
In the left picture we see one of the ventilation fan grilles along with the 50amp Anderson Power Connector.
In the right picture we see the other vent fan and the antenna ports. The upper is for the FTM-350, the lower 2 lead to the FT-857D: Upper – VHF/UHF and lower – HF
Issues, Problems, Pitfalls, & a Part 3
As you might have gathered while reading these first two posts, not everything was peaches and cream during either of these builds. Rather than being discouragements, each has been a lesson learned and a challenge to overcome. To me, that is the fun of DIY. However, if I’m going to be a good host I think it best to at least give you a heads up on some of the issues I dealt with and how I dealt with them. But to be fair, this installment has already been a long read and so I’ll cover them in the 3rd and final post to give them the attention they deserve. So until next time….
Before you go, I thought I would give you a rundown of the parts I bought for GB1 and GB2 is case you’re interested for your own build. Where possible I’ve provided links to where I got the item. As noted on the home page, I’m an Amazon Associate and as such, I earn from qualifying purchases when that link leads to the Amazon store. It costs you nothing extra and I get a little bit that helps support the site. Thank you in advance.
The subject of go boxes is one that has many, varied opinions. I don’t think it would actually start a big argument, but like any other topic in ham radio, there are some strong viewpoints on the subject floating around. Sort of like the old AM vs SSB arguments of a few decades ago, or the newer, voice vs digital modes, that is popular today. And no, I’m not going to weigh in on either of those arguments because honestly, I don’t really care. I like what I like and the hobby is large enough for every viewpoint and area of enjoyment. I’m also not going to say that my perspectives on go boxes (or anything else in amateur radio for that matter) is or is not the best way to go about building one. I’m just going to show you my builds and hopefully give you a few ideas that might be useful in your version.
In this series I’m going to show you two go boxes that I’ve built and share my perspective on what went into each and why. Keep in mind these are my opinions and not gospel truth. The fact is, the definition of a great go box is one that:
fits your needs
works for your situation
falls within your budget (or what the xyl will let you spend)
and that’s it. No magic formulas or heady theory on this one. Also, most versions of a go box that I’ve seen online or in person have one thing in common; if you don’t like something, or find that your goals and needs have changed, you can revise or alter it! That’s the beauty of DIY!
Also, in my first box, all the radios were purchased new along with all of the support items, except the box itself and the screen. In Go Box #2 (covered in Part 2) the radios were purchased at a swap meet, with a new components added to round it out. The point is that you don’t have to break the bank to build a good go box, and depending on your design, it can be expanded as needs and budget allow.
So what is a go box? Well, for me it’s a box that’s preset with the equipment needed to communicate in a specific set of environments or situations. That’s a broad enough definition for most anyone’s need and leaves a lot of room for experimentation and innovation. I currently have two and both have been through more than one iteration as I’ve used them and refined them based on in-use assessments and, in both cases, some mistakes made in their first versions.
I would also like to take a moment to differentiate go boxes from go kits. At least for me, a go kit is a collection of items, including a radio (possibly more than one), that is packed in a bag, sack, backpack, etc., that can be transported to a location, unpacked, assembled, plugged in, turned on, and operated. Though very similar in nature, the go box is ready to go and only has to be opened up, plugged in, turned on, and operated. Little or no assembly required. I’m probably splitting hairs, and it’s my opinion so no hate mail.
I hope the example below gives you ideas for planning your own setup. So, without further ado, lets get into Go Box #1.
Go Box #1
To the right is Go Box #1, or GB1 for short. It’s my EM or Emergency Management response kit. GB1’s purpose to provide most every standard communication method/band that I might need to monitor in a disaster response. It’s built into a 6 space, shallow depth, 19″ equipment rack, normally used for av equipment. It has removable front and back covers, however the front is also hinged on one side so that it can swing out while still remaining attached to the rack.
There are four radios in this kit and they are:
Yaesu FT-891 (HF/6M) – Long distance communications with voice (SSB/AM) and digital modes
Yaesu FTM-7250/DR (VHF/UHF/Fusion) – Short distance communications with voice (FM/Fusion) on local repeaters and simplex if required
Leixen VV-898 (VHF/UHF/FRS/GMRS) – Just in case these modes are needed (see below)
Uniden Pro505XL (CB) – Keep track of what’s happening on the roads and in neighborhoods
This lineup allows me to monitor or establish communications with just about anyone in the civilian world. To me, this is an important capability in a disaster scenario. Now before anyone gets on their soapbox about needing a license to operate on GMRS, and that the VV-898 radio has too much power and no fixed antenna for FRS, you are absolutely correct! However, their purpose is to listen, and if absolutely necessary, could be used as an available means to get a message through in an emergency.
Please understand that I will never encourage anyone to knowingly or intentionally violate the law or FCC regulations!
That being said, there is absolutely nothing wrong with having a capability, just in case. I would rather have a capability and never use it, than not have it and need it in a crisis.
So, aside from the radios, what else is in the case? Well here is the rest of the equipment and usage in this application:
ATU-100 Automatic Antenna Tuner – used with the FT-891 and provides the capability to tune from 1.8 to 50Mhz and up to 100watts. Yes, I know it won’t tune 6M (as I reluctantly found out one evening on a local 6M net) but other than that it works great. I may replace this in a future change up if I find on that will fit the space.
Raspberry Pi 4B/2G in an Argon One V2 case – this is the literal brain of GB1 and allows remote control of the FT-891 for digital mode work and most any computer related need. It runs KM4ACK’s (Jason) Build-a-Pi software suite of ham radio applications. You can find his Youtube videos here.
SUPERNIGHT DC 12V 30A 360W Universal Regulated Switching Power Supply – Power for the rack.
Chunzehui F-1006 Low Loss Power Gate PWRpath Module – allows seamless switching between the internal power supply and an external battery plugged into the large 50Amp Anderson Plug in the lower left corner of the back of the rack. It will also charge the battery while on the power supply.
Chunzehui F-1005 9 Port 40A Power Splitter/Distributor, 1 Input and 8 Fused Outputs – distributes power from the Power Gate module to all of the equipment in the rack.
The switch panel has switches to control the RPi, Screen, USB Charger, 12V Socket, and blue LED strip light for night work.
Various cables, adapters, switches, etc., to connect everything and make it all work.
Oh, but wait, I almost forgot about the screen! Well this baby was one of my first DIY ham projects, from several years ago, as part of a previous attempt at a go box. The go box itself failed, but the screen was a success. In essence, it’s just a laptop screen from an old HP laptop I had that died, but still had a good screen. I’ll not go into detail here on how to make it when another DIYer (DIY Perks) on Youtube can explain it much better than I (Also, he has pictures, and I didn’t take any cause I never thought I would be doing this blogging thing). So check out his video here.
Well that’s GB1 in a nutshell. I hope this has been informative and gives you ideas for your own go box. If you have a question or comment please leave them in the comment block below. Please stay tuned for part two where I’ll describe GB2. This one is a little more unique and took some major noodling to get right. Also, I will include a detailed parts list for GB1 and GB2 in the next installment. So until next time, 73’s!
Like many of you, life here at the DIY Ham has been a challenge these last few years. When we started the DIY Ham it was our intent to be a little more timely with posting projects and various tidbits of info. Alas, that did not materialize. Every time we thought we might be getting ahead and would have time to get some content published, another pull from life would tug and we had to respond. But I think we are in a position to get back to it, so I thank those who have visited the site and provided generous comments. I only hope that our future posts will be useful to the community.
To that end I want to give you a preview of a couple of articles that we are currently working on:
Go Kits – A look at portable stations for various needs and situations. In this article we will address a number of concepts and questions that the ham needs to understand and answer to get the most from their investments of time and equipment. We will also look at various examples assembled by WA4OPE, and possibly others if we can persuade them to share.
3D Printing – Sometimes viewed as one of the holy grails of diy, it is a new frontier for the DIY Ham thanks to Christmas gift giving. This will be a basic overview and chronical of my learning curve with tidbits and links to resources that have been very helpful.
Portable Antennas – This will likely be a series that will look at the various options for antennas and will include: dipoles, end feeds, whips, and loops. Maybe I can get some of my acquaintances to contribute. We’ll see. 🙂
Well that’s it for now. More to follow, soon I hope.
Those of us who live on small, urban lots, or live under the auspices of HOAs or CCRs, routinely lament the frustrations of a limited ability to get on HF with a good antenna system. In recent decades an entire subculture of ham radio has sprung up in the area of stealth/invisible antennas that can be put up either hiding in plain site, camouflaged to blend in, or both. One of the most unique, to me, is the “Flagpole” antenna. This article describes my experience designing and building my version. Obviously this isn’t the only way to build one, and it certainly has shortcomings. However, it works surprisingly well.
Let me pause a moment up front to say that I didn’t get pictures of all parts of this build. Where necessary I’ve tried to provide more detail or create drawings to aide in understanding my logic and methods. Comments and questions are certainly welcome, as long as they are constructive and genuine. Finally, this post was created for information and entertainment purposes only. I make no claim that this project will meet your needs or work in your situation. You are also solely responsible for any attempt to recreate this project and I’m in no way liable for injury (from your own actions or those of your spouse against you) should it happen. So with all that out of the way, let’s begin!
Why a Flagpole?
“I pledge allegiance to the flag, of the United States of America, and to the republic for which it stands, one nation, under God, indivisible, with liberty and justice for all.”
United States Pledge of Allegiance
First off, I’ve always wanted a flagpole in my yard that will let me fly the American flag 24/7 (lighted of course) and show my love of this country. I happen to be proud of what it represents, and even though we have our issues as a nation, we are still the greatest country on earth, in my opinion. I personally think every home should display the flag, but that’s me. And, don’t get me started on those with no respect for it. That would be 3 or 4 posts at least and would likely result in my being booted from every social media platform in existence so we will leave that one alone.
Second, although I’m not subject to the issues associated with HOAs or CCRs, I do live in a 100+ year old historic home, in a historic district, on a very small, corner, urban lot. In fact, my back yard is literally a 5′ wide strip that runs between my house and the neighbor’s driveway. That’s not a lot of room for an antenna of any sort, so that leaves two “side” yards and the front. The side away from the corner, where my patio is, has the added issue of being surrounded by power and service lines so that a permanent antenna of any height is also a no-go. What remains is the front and corner side of the lot. Since I also need the cooperation and approval of my wife (and the included WAF – Wife Acceptance Factor) whatever I put up would need to look good and not be an eyesore to her or the neighbors. That being said, I do have an understanding wife who also happens to be licensed as a ham (technician) so that does help.
Third, I didn’t want to go to the effort of installing a bunch of radials in the grass that would inevitably find their way to the shaft of my lawnmower blade. I know the grass is supposed to grow up and pull them down (so they say) but I also know my yard and my lawnmower. Since it’s mostly weeds, that perspective is likely suspect. Enough said.
So being retired Navy, and of a patriotic nature, I began looking for a flagpole antenna design and that’s when I experienced the sticker shock of ready made commercial offerings. Now don’t get me wrong, the products I looked at appear to be well made antennas and I think they are worth the price being asked. The testimonials look genuine and likely based on sound engineering, practical designs, and experience. However, being limited in funds (remember that 100+ year old houses also require periodic work) I needed a different solution. I also like to build things (this is of course the DIY Ham) so this looked like an interesting challenge and an opportunity to solve two issues in one build. After a good deal of searching, I ran across this YouTube video by John Portune, W6NBC, describing his experience with DIY flagpole antennas. Based on the information presented in John’s video, and the realization that I already had some of the materials he had used on hand, I began doing targeted research and came up with a design that would fit my needs, and pass the all important WAF.
The Design & Odd Parts
If you take the time to watch John’s video, you will probably note that one of his first versions was built from the aluminum poles used by the military to hold up camouflage netting. These have been a staple offering at hamfests for years, and are relatively cheap to obtain. It also happened that I had 11 of these that were given to me by my neighbor (the one with the driveway 5′ from the back of my house) when her husband passed away a few years ago. Having used these to put up a 40′ dipole support mast at our last field day in 2019, I knew they were pretty strong, but could be wobbly due to the flexibility of the slip joints between the poles. I also found that they would just barely slide into 2″ schedule 40 PVC plumbing pipe. Looking further in my material pile, I found a 5′ length of 2″ aluminum tubing, also schedule 40, and a plan started to come together. Figure 1 shows the basic sketch of the antenna I came up with. For the most part it was followed, with a few minor tweaks along the way.
Basically, it’s an Off-Center Fed Vertical Dipole antenna. Based on John’s information and my own research, I knew that putting the feed point off-center would yield an impedance of around 50 ohms and feeding the coax up the center of the lower, aluminum tubing section, would keep it from looking odd and be more like a flagpole. Also, since the camo poles (the green section in Figure 1) fit inside of 2″ pvc pipe, the pipe could act as a radome of sorts for the upper portion, and create a consistent 2″ pole from bottom to top.
Here are the basic parts/materials needed to build a 20′ flagpole/antenna:
1 – 5′ section of 2″ schedule 40 aluminum tubing/conduit
2 – 10′ sections of 2″ schedule 40 pvc pipe
1 – 2″ pvc coupler
1 – 2″ pvc cap
1 – 5′ section of 1 1/2″ pvc pipe
1 – 48″ section of 1 1/2″ hardwood dowel
5 – aluminum camo net poles (approx 46″ in length)
30+ – 10-24 x 3/4″ stainless steel machine screws
8-10′ – RG8/LMR400 coax
1 – remote tuner
1 – 1:1 choke
1 – can of spray paint (in whatever color you desire, I used white)
1 – flagpole truck/pulley
1 – rope cleat
50′ – poly rope for use as the halyard
10″ – 3″ diameter heat shrink tubing
Figure 2 shows one of the camo net poles used to build my antenna. As you can see there is a joint collar at the bottom that is welded to the main tube and a tapered nipple at the top that fits neatly into the lower end of the next pole. They are also a butt ugly green, so hiding them inside the 2″ pvc will help the aesthetics as well. Those are the basics for the flagpole/antenna itself. Of course you will need some way to mount it and also a way to get the transmitter feed out to it. You will also need a selection of tools such as:
Drill (cordless or wired)
Drill bits (various sizes
Tap for stainless steel screws
Countersink bit for stainless steel screws
Handsaw or miter saw
Various other hand tools
Upper Section Build
The top section consists of the aluminum camo poles sleeved inside the 2″ pvc pipe. This is then capped by the 2″ cap after attaching the truck/pulley just below the line where the cap will seat itself. Start by assembling the camo poles as shown below:
Two sections should be held tightly together (and aligned straight) while drilling and tapping for the stainless steel screws (Figure 3). This will lock the two together and provide significant strength to the overall pole. Each screw must be countersunk below the level of the joint collar in order to clear the 2″ pvc later. Place two screws at each joint, 180 degrees apart. Also, the line of screws on each side of the assembly should form a straight line up opposite sides of the assembly. Although I didn’t do it in my assembly, you may want to add a product, such as Jet-Lube, to the joint to minimize corrosion and promote good electrical conductivity. Now would also be a good time to lightly sand the aluminum weld joints level with the joint collar. Continue this process with the remaining 4 poles and you will end up with a length of about 19′. Measure from the bottom (widest point of poles) up 16′, mark and trim using a hacksaw. This will give you the proper length for the upper section. Next you will need to sleeve the pole assembly with the 10′ sections of pvc pipe, starting at the bottom.
Begin with the first 10′ pvc pipe and before sliding it over the camo pole assembly, place it alongside with the bottom ends flush. Mark the pvc with either a sharpee or tape at each of the joint collars to allow additional fasteners to be used to connect the pvc to the assembly. Once the marks have been made, slide the pvc pipe over the camo pole assembly taking note of where the joint screws are in relation to the circumference of the collar and pipe. The bottom of the camo pole assembly and the bottom pvc pipe should be flush as shown in Figure 4. At each of the collar marks on the pvc, and at 90 degrees from the camo pole assembly screws, mark for another set of screws, 180 degrees apart, to lock the pvc to the internal poles. This will add more strength to the overall assembly and still remain flexible to sway gently with the breeze.
As discussed earlier, the joint collars are a tight fit, but as can be seen in Figure 5, there is a gap between the body of the poles and the pvc pipe. This is not an issue except at the point where the two pvc pipes come together and at the top of the last camo pole where you had to trim the length. You will need a spacer insert for these two places. Since the gap is approximately 1/8″, I was able to use the inner plastic ring I had saved from a kapton tape roll that was trimmed to fit. This makes up the gap and allows the two pvc pipes to be anchored at the transition point. A short section of pvc pipe with a section removed could also be used as long as the thickness is about 1/8″.
At the locations where you marked for the additional screws, drill, tap, countersink and install them. The depth of the countersink is not as critical for these screws, but should be somewhat even with the pvc pipe. Be sure to drill, tap, and countersink for screws at the transition ring as well leaving enough to engage the upper pvc pipe that is added next.
Once you complete the first 10′ section, measure from the top end of the pvc pipe to the top end of the inner camo pole assembly. This should be approximately 6′. To this measurement add an additional 6″. Use this total to mark and cut the upper pvc pipe before sliding it over the remaining camo pole assembly. The additional length is to allow for the installation of the truck/pulley assembly later on without making contact with the camo pole assembly. Once you have it cut, repeat the marking of the joint collars done for the lower section and then slide it into position. As you slide the two pvc pipe sections together, consider applying a small amount of sealant to the joint to keep water out of the interior of the antenna. Drill, tap, countersink, and install the holding screws, including through the lower transition ring and the upper shim ring between the top of the camo pole and the pvc pipe. Set the top section of the flagpole antenna aside for now.
Lower Section Build
The lower section of my antenna consists of a 4′ section of aluminum 2″ tubing cut from the 5′ piece listed in the materials list. The remaining 12″ will become the portion that mounts the overall assembly to the base. Since the antenna design is that of a vertical dipole, the upper and lower sections must remain electrically isolated from each other and the mount. To accomplish this the 4′ x 1 1/2″ hardwood dowel is cut into two equal pieces. One is used to connect the upper and lower antenna sections and the other to connect the lower section to the 12″ mounting tube. It turns out that the internal diameter of the camo poles is just over 1 1/2″ and with a couple of pieces of heat shrink tubing as shims, the dowel is a snug fit. For the 2″ aluminum tubing, a section of 1 1/2″ pvc pipe, with similar heat shrink shims makes up the difference for the dowel in that part (and the mount). The 5′ section of 1 1/2″ pvc should be cut into a 12″ section for the mounting tube, and the remaining 4′ for the lower antenna section.
Prior to installation, both dowel sections must be prepared by boring a hole through the center of the dowel between 13 and 14″ deep. This is then followed by a cross hole that intersects the end of the center hole to allow the coax to pass, up to the union between upper and lower sections and from the bottom of the lower assembly through to the upper dowel as shown in the details of Figure 6.
Once the interior holes have been drilled, feed the coax through both ends and slide into the 1 1/2″ pvc pipe and then into the aluminum tube. You should end up with 10-12″ of hardwood dowel protruding from both ends of the tube with coax extending out both as well. The lower end should be of sufficient length to reach the remote tuner output (12-24″) and the upper end should be trimmed and separated into the braid and center conductor. The braid will need to be connected to the lower tubing and the center conductor prepared to eventually connect to the upper section when the two are joined. The lower end will slide into the mounting tube with the 2″ pvc coupler used as an isolator between the two aluminum tubes. You will need to cut a slot in the upper part of the coupler to allow the coax to pass out. The hardwood dowels and pvc pipe will all need to be anchored in place using suitable screws. Take care, however, that you do not penetrate the drilled passages in the dowels that contain the coax to prevent damage. In my case I used screws commonly used to hang cement board (because that’s what I had on hand) and predrilled the aluminum tubing. The completed lower assembly should look something like Figure 7. Note the coax extending off to the right. (Incidentally, the other pvc item in the picture is the base of an experimental 6m center feed vertical dipole that happens to work very well and will likely be the subject of a future post.) At this point, all that remains is to assemble the upper and lower sections of the antenna, add the flagpole hardware, install it, connect it, and test it on the air.
Assembling the final flagpole/antenna begins with joining the upper and lower sections together. In my case, I left the center conductor bare and sticking up along side the hardwood dowel that would slide into the upper section to make contact with the inner portion of the lowest camo pole. This friction fit appears to be working well. I also ended up with a gap (on purpose) between the upper and lower sections to prevent electrical contact between the two. This was covered with a 10″ section of 3″ diameter heat shrink tubing and is the small skinny section a little less than 1/4 the way up the finished pole in the opening picture.
As you can see it’s barely noticeable at a distance, and once painted, barely visible. Figure 8 provides a close up view of the heat shrink after it has been painted white. A word of advice, to minimize frustration slide the 3″ heat shrink on to one of the sections prior to joining them. This will make it easier to simply slide it into place and shrink it with a heat gun. You may also want to fill the space with dielectric grease to ward off water intrusion.
Once the two sections have been put together, take the time to paint the entire assembly. Once dry, the truck/pulley must be attached at the top as shown in Figure 9 (leave room for the cap), and the halyard cleat, shown in Figure 10, added at a convenient height (about 3-4′ above ground). I also fitted the top of my flagpole with a 2″ ball (also shown in Figure 9) . I scavenged this from a Harbor Freight telescoping flagpole I use as a temporary mast for portable work. I simply through bolted it to the 2″ pvc cap and friction fit the cap to the top. This will allow me to change out or service the truck/pulley, should I ever need to do so.
The last step to putting the flagpole/antenna in the air is installing a suitable base mount, preferably one that will allow the pole to be lowered to the ground for servicing and to prevent damage in severe weather. I built my mount from salvaged aluminum channel and thick walled square tubing and is shown in Figure 11. I’m hesitant, due to the stresses involved at the ground for a 22′, 2″ mast, and the potential liabilities associated with it, to share details of my own solution. Although mine is robust (in my opinion) I do not want to potentially lead someone astray in this particular area. DX Engineering is one source for ground antenna mounts that will work well with this build at reasonable prices. I’m not saying you can’t build your own mount. I actually encourage you to do so, if you have the knowledge or know someone who does and can help you. That is what this site is all about, doing it ourselves. However, you need to do your homework and fully understand the physics and forces involved before attempting a DIY mount. You also need to understand the liabilities you assume when you undertake such a project. Okay, off my soap box. On with the show.
Hooking it Up & Getting on the Air
Obviously, the main purpose for this exercise is to end up with a usable antenna. In order to do that it needs to be connected to your transceiver or transmitter/receiver. For this type of antenna that will require the use of a remote tuner, and I also highly recommend using a 1:1 choke (not a balun as it is routinely and mistakenly called) between the tuner and the coax feeding the shack to keep common mode currents out of the shack.
The tuner I’m using is the LDG RT-100 with the RC-100 Controller as shown in Figure 12. The RT-100 is mounted at the base of the antenna (in my case inside a plastic container) and the RC-100 sits in the shack next to the radio providing power to the tuner over the coax. As recommended, I also have a DIY choke that is wound on a FT-240-31 toroid to cover 80-6m (9 turns of RG-8X) and placed in a project box with SO-239 connectors on either end as shown in Figure 13. Both the tuner and the choke are in the plastic container with the coax coming up through the base via buried conduit. The signal then exits via a bulkhead SO-239 on the side facing the flagpole. Attached to the outside end of the bulkhead connector is a lightening arrestor followed by the antenna coax. The arrestor, the tuner, and the flagpole base are all connected to an 8′ copper ground rod driven in next to the base. All of this is shown in Figure 14, and before I get the comments about no wrap on the exposed connectors let me say that I’ve held off on that until my initial testing is complete. I will get to that soon, I promise.
The tuner is in the bottom of the box, held down with double sided tape, with the choke sitting on top. Also shown in the box, are a 14 gauge electrical wire and a cat6 cable, both running with the coax through the conduit back to the shack. The wire is an extension of the shack and station grounds to the antenna grounding system and the cat6 is for future expansion/projects.
Once everything is set up and verified working, it helps to add a little bit of landscaping to make the project look good and more like a flagpole. Obviously, that part is my wife’s area of expertise (although I did have to haul the pine bark, and dirt, the landscape stones…) and I’m happy to let her handle that part since she enjoys it so much and it shows in Figure 15.
So, does it work? In a word, yes. Is it perfect? No, but I’ve made some decent contacts locally on 10m ssb and along the eastern seaboard (US) on 40m using FT8 and JS8Call. I’ll continue testing to see what the limits are, but it appears that it will work from 40m to 6m with about 1.6 tuned swr and 80m between 2 and 3 swr. I’ll update this post as I work more with it. Thank you for reading this far and please provide comments and feedback. We are always learning in this hobby, and we learn best when we share information and experience. God Bless.
WA4OPE – Dave Hewlett
Updates – Performance
Since I published this article I’ve been doing some testing and have also finally plotted the antenna in EZNEC (yes I know I probably should have done that first but, you know…).
Performance wise, the antenna tunes up on all bands from 80m up through 6m with no problem. I am considering adding the 4:1 balun back in to make it a little easier on the tuner. I’ve been able to make FT8 contacts through out a good portion of the US and the Caribbean on 80m, 40m, and 20m, and I’ve finally been able to check-in to Winlink Wednesday on HF for the first time. Overall, I’m pleased with the antenna and the flagpole as well.
Below are plots from EZNEC Demo v.6.0. The main reason I never plotted the antenna in the first place was the fact that I got a missing file error every time I tried to run, reload, etc. the program. After a little research, I determined that it was issues with the VB runtime module that had been installed last summer. After removing both and reinstalling the software, it finally works. So without further ado, here are the plots:
If you have any questions please let me know. Enjoy.
Where we celebrate the Do-It-Yourself spirit of Amateur Radio!
I know this is a little out of order, as far as introductions are concerned, but my first post about the patron saint of ham radio was just so interesting I couldn’t resist. Anyway, here we are. Welcome to my humble site where we hope to highlight various DIY projects that I’m working on, or have completed, and those of you, the reader, in the area of ham radio.
My name is Dave Hewlett, WA4OPE, and I’ve been a ham, on and off, since my teenage years in the late 1970’s. I was first licensed in Plant City Florida in Jr. High School at our radio club. My first Elmer, Brian Glenn (WB4SWS) taught many of us about the hobby of ham radio and introduced us to people from around the world at our school station (WB4DTH) in his classroom. The love of electronics has stayed with me these many years, and though I took a break from radio following high school and joining the Navy, I eventually came back to it in 2002 getting my Technician license, followed up in 2017 when I tested for General and Extra.
Since rejoining the community of ham radio I’ve been increasingly interested in building various aspects of my home, mobile, and portable stations, and that is the genesis of this website. It is my hope that many of you will join in sharing your projects, tips, thoughts, failures (yes we do learn from mistakes), and obviously successes. So welcome aboard.
Yes you read that right, SP3RN is considered the patron saint of amateur radio. You see SP3RN belonged to a Polish Conventual Franciscan Friar named Maximilian Kolbe who was arrested by the SS in WWII and sent to Auschwitz for, among other things, using his amateur station to report on the atrocities being perpetrated by the Nazis on the Polish people. He would later volunteer to be sent to starve to death in place of another prisoner. He would be canonized in 1982 as a martyr by Pope John Paul II. You can learn more about this amazing amateur at the links below.