Has it really been that long?
I didn’t realize it’s been over three years since the last time Off Grid Ham specifically addressed go boxes. If the internet discussions and on air chatter are any indicator, it’s a very popular way to operate. It’s way past time to revisit the humble ham radio go box and come up with some fresh ideas.
In the last three years I’ve noticed an uptick in ham radio go box deployment. There are even entire social media pages dedicated solely to go boxes (or bags or whatever your thing is). I think there are several reasons why. Many operators live under homeowners’ association rules that severely limit having a fixed antenna. Theses operators may have no choice but to hit the road. Others want something they can take camping, for SHTF purposes, or EMCOMM. The various special event stations from parks and other significant places may be driving the trend too. There’s also new equipment manufacturers offering low cost gear. This opened possibilities to people who could not otherwise afford a dedicated go box.
As before, this is not going to be a step-by-step how to on building a ham radio go box. There are too many variables and too many individual choices for me to come up with a plan that works for everyone. Instead, we’ll go over some concepts to consider and questions you’ll need to answer before you begin.
Defining priorities.
What is the Number One priority for your ham radio go box? It it portability? DX-capability? Data modes? Keeping the cost down? Before you can construct a go box, you have to decide what trait is the most important. From there you can work in secondary needs. As with everything, there will be compromises, and some things are mutually exclusive.
The main reason ham radio go boxes do not live up to expectations is because they were not built to expectations in the first place. Or possibly, what you thought was a Number One priority turned out to be not such an urgent issue after all. Years ago my first go box was a huge fail because my Number One priority, cost savings, meant giving up so many other smaller things that they made the cost savings not worth it.
The main parts of my new & improved, much lighter ham radio go box. Left is a 27 watt folding solar panel. Top is a DC power box which includes a 13 amp-hour lithium battery and the charge controller. Right is a random wire antenna. Not shown: Alpha Antenna FMJ.
I used an old Yaesu FT-757 GX II radio. I also dug up an inverter, a solar controller, an FT-2900 2-meter radio, a 100 watt solar panel, and some various plugs and connectors. All of this stuff I already had. I built a nice wood box to mount everything in. My out of pocket cost for the entire project was less than $100.00, and most of that was for a 35 amp hour SLA battery. It looked impressive. I felt like a boss!
Well guess what? I achieved my goal of keeping the cost down, but my ham radio go box was so clunky and heavy that I didn’t care. Between the battery, the wood box, and all the other stuff, I could barely move that beast by myself. There wasn’t much “go” in that go box, unless I invested in a forklift too. I thought saving money was my Number One priority but I gave up too many other attributes to make it worthwhile.
That was my lesson in not only defining priorities, but also considering what else I have to give up to attain that priority. I inadvertently buried the cost savings under all the other problems. I used that go box only once or twice, then dismantled it.
What comes next?
After admitting defeat in my first attempt at a ham radio go box, I reexamined my priorities. I decided that having something light and truly portable was what I really wanted. Not necessarily “backpack portable,” but at least nimble enough to be carried a reasonable distance (say, a mile or so) by one person and still have enough power and functionality to be a practical, working radio station. This criteria would also have to include the antenna and power source. And speaking of power sources, I wanted off grid battery charging capability.
The FT-757 all by itself weighs over 11 lbs./5.20 kg. It had to be jettisoned from the project, along with that 35 amp hour battery. On my second attempt, I traded transmit power for less weight by getting a Yaesu FT-817 QRP radio. I then matched the rig with a DC power pack and random wire antenna.
The entire package came to under 20 pounds/9.10 kg and fit in a backpack. My new ham radio go box (or go bag, if you will) worked beautifully! Earlier this year I invested in an Alpha Antenna HD-FMJ vertical and I upgraded the DC power pack to lithium batteries. The antenna added bulk and weight, but did not negate the spirit of the project. I was much happier and got better results than when I had the abominable ham radio go box from hell.
To each his (or her) own.
I’m not going to sit here and tell everyone about how my setup is the perfect ham radio go box because, well, it’s only perfect for me. And quite honestly, nothing is truly “perfect” anyway. You are your own person with your own needs, priorities, and budget. While it’s fun and informative to glean ideas from others, in the end you are the only one who has to live with your creation.
One priority that should be built into every ham radio go box –no matter what else is at the top of your wish list– is flexibility. It’s very likely your needs will change over time. Unless you are wealthy enough to start from scratch with all new equipment every time the whim hits you, it’s a good idea to make your box scalable and reconfigurable. As much as I like my current setup, I’m already plotting my next iteration of radio-to-go. I like to experiment and change things up, but I’m not rich, so I make my go boxes with the assumption I will be repurposing the gear at some point.
The goal of this mental exercise is to encourage amateurs to put a lot of serious thought into their ham radio go box before they start spending money and assembling everything. I made the mistake of only looking at the bottom line and because of that shortsightedness my first go box was a huge fail. Experience is a a good teacher; other’s experience is an even better teacher!
It’s all about compromises and deciding what you absolutely must have to do what you want to do. Everyone has different requirements. It’s a matter of changing one’s thinking from “what I’d like to have” to “what I absolutely need”. If I’d include everything I’d like to have, I could fill up a good sized steamer trunk. As it is, mine is probably overloaded. But then it’s my “I’m going fishing and I’m taking my radio stuff along in case I get bored” bag, and is intended to be lugged along in a vehicle, not carried long distances. So it has a fairly hefty AGM battery, the magloop antenna and it’s tripod and mast, the 818, VHF/UHF handheld, bits of wire, flashlight and spare batteries, a butane soldering pencil, a few essential tools, fire making stuff, first aid kit, paracord, tape. Still it’s better than when I was with ARES when I was lugging around enough junk in the back of the Jeep to equip a small repair shop because I knew someone at an exercise or event would burn up, blow up, or break something or forget something essential.
I still want to put together something much more portable that I can stuff into a backpack and take when I’m out on the trails with the bicycle. And I still want to put together an ultra compact RaspberryPi system for digital that would be backpackable.
What should go into a go box could be debated forever. At some point you just have to jump, hopefully after giving it some careful thought. I just finished a go box re-do and I’m already planning the next one.
I know people go on about quaterwave and similar verticls, but they are more or less usless for portable or bug out type comms because they are way way to ineficient due to what you do with the “other half” of the antenna.
By “other half” of an antenna people should realise that to get current to go up an antenna like a quater wave you have to suck in a coresponding quantity of current from somewhere else. This goes back down your feed line to your transmitter. Thus the Quater wave is realy a halfwave dipole that is “current fed” thus very very suceptable to any kind of impedence in the “other half”. Which is why on the higher HF bands you are much better of if you can mounting a halfwave dipole vertically.
When antennas are “electricaly short” via inductive or capacitive loading the impedence problem is even worse. Which is why HF mobile with 100W has a farfield strength of less than 1W from a vertical halfwave dipole, and any kind of corrosion will take it down to the very low milliwatt equivalent or less. The reason people tend not to notice is that with a properly set up halfwave dipole you can work the world with less than 50mW in CW and the other modern narrow band digital modes.
So going portable with 5W or less and a decent antenna will get you comms range but without the weight (oh and don’t forget some mobile rigs draw 4A in RX even the 817 draws more than 300mA, a portable DSP SSB SW receiver with a little tweeking can work down on 50mA or a lot less, so gives you atleast 6 times the RX life for the same battery than the 817 and 80 times that of those 100W mobile rigs).
So what to do about the antennas “other half”?
The simple fact is at any non fixed location you can not dig in the 16-128 radials that are cut to a specific length for each band. Even banging in long earth stakes does not help (more than 1-1.5ft in the ground does not improve anything for any given diameter, increasing the diameter or more correctly surface area does). But worse whilst you get told about good ground radials reflecting the signal up, –which is bad news often for local and DX work– generally ground radials work quite badly so all you do is “warm the ground”. Hence the old joke of “Quaterwave verticals work equally poorly in all directions”.
So are there better antennas to consider the simple answer is yes. One simple solution is to go from a current fed antenna to a voltage fed antenna which is high impedence thus ground immpedence becomes a lot less important. The End Fed Half Wave (EFHW) is one such antenna, and as long as you can push in a long tent stake and crock/alligator clip your ground from your 64:1 broadband matching transformer to it you will get out. If you inverse V mount it’s middle where all the radiating current is on a fishing pole etc you don’t need the feedline with it’s,weight or loss. Put up in a tree the thin wire you can use is nearly invisable even quite close. The problem with an EFHW is it needs to be cut fairly accurately for the frequency of operation, so it’s not an ideal antenna (the Zepp or Jpole are varients using a quaterwave transformer the W3EDP https://www.nonstopsystems.com/radio/pdf-ant/w3edp-4fba.pdf is a multiband varient)
If you pick the right length of wire (ie not a quaterwave or halfwave on the frequencies you use) you can use a 9:1 unun this is often called a “Random Wire” it needs better grounding or preferably a counterpoise that is raised about 4ft of the ground especially at the end. Due to it’s increased capacitance to ground the counterpoise can be quite a bit shorter than you might expect.
Both these antennas also have another issue which is their radiation pattern is not omnidirectional so you need to be able to tell which orientation you need to put them up in.
Another antenna similar to the vertical dipole is the vertical OCF antenna. Very approximately you feed 1/6th of the way into your halfwave dipole rather than at the center the other 5/6ths go up a tree or what ever is handy. This brings the feed point a lot closer to ground level which makes taking the feedline out at 90degrees much easier. Further you can use ladder line as the feed line which has a number of advantages. It is also multi-band in operation. I’ve used one with the 1/6th coming down of a 10meter pole at an angle of ~45degree with a short length of light weight feed line comming off back towards the base of the pole and the matching transformer on the back of the TX. The 5/6th then going of to a tree via fishing line.
So far none of these antennas require an ATU, just a matching transformer of some kind.
If we are going to use a vertical with an ATU we can get a much broader operating range from it but we still have the issue of radials and their inefficiencies which is just not on for portable use. So we need raised couterpoises supprisingly unlike radial you don’t need lots of them. One will actually work with a slight distortion in the radiation pattern, two help balance that out and three or four work about as well as you can expect on their own. Unfortunately they need to be the right length to get the best efficiency thus watts in the air.
There is a way to reduce the problem, one is to use a rollup tape measure or similar easily adjustable length for a counterpoise. The other is to have a second tuning unit, that tunes the counterpoise. Called a Ground Tuning Unit (GTU) they are in effect a series tuned circuit and RF ameter. You put the receiver into SSB/CW and tune the ATU for maximum noise, you then adjust the GTU to get a better signal. When you TX a carrier you adjust the ATU and GTU the ATU to give minimum SWR reading and the GTU to get maximum RF current into the counterpoise. A GTU also helps a lot if your TX is not at ground level.
The other thing you can do with a GTU is get rid of the counterpoise wires. In essence all you need is a conductive mat on the ground which can be only a couple of square feet and you tune for maximum current.
There are a couple of people up in the north of England that do this with those “granny bag” type shopping trollies that they take down to the foreshore at Blackpool and the like. They operate portable all the way around the world and chat to people in New Zeland. It only takes them a minute or to to “set up” on arrival and a lot less than that to “tear down” on depature, the longest time delay being getting the fiberglass fishing rod type poles down.
I would realy suggest people look into GTU’s if they are operating QRP Portable. VK3YE has a couple of websites and U-Tube channel you can watch to find more information on GTU’s and tuned counterpoises.
https://dailyantenna.blogspot.com/2019/03/tuned-counterpoises-for-hf-vertical.html
https://dailyantenna.blogspot.com/2019/10/two-ground-tuning-units-for-portable.html
https://www.vk5pas.com/uploads/1/3/9/8/13982788/-guide_to_building_a_portable_station_complete_with__gtu__1_.pdf
Hi Clive, I apologize for the delay in getting your reply posted. My anti-spam software allows comments to be posted right away unless they violate certain criteria, in this case the outbound links in your comment tripped the alarm. I am supposed to get an email when a comment requires manual review but for some reason that didn’t happen and I didn’t see your comment until now. So I apologize that you were an innocent bystander and for taking so long to release your remarks for publication. I do personally read every single comment and email sent to this blog.
Anyway, about your comment, thank you very much for the detailed reply. Your response itself could be an Off Grid Ham article. As you point out, there are a lot of compromises to be made with portable antennas. For my own use, have two antennas: A random wire with an unun and a counterpoise (yes there is an article about it here on OGH) and an Alpha Antenna FMJ. They both work very well but I favor the FMJ because it is easier to set up.
I will look at the links you provided and possibly use what I learn for another article. Most of the articles that appear on Off Grid Ham have their origins in reader feedback & suggestions, so thanks for adding to the knowledge base. I tell others that I don’t need to come up with ideas for articles…my readers provide the topics for me!
Any reason why my post failed moderation?
Any reason why my previous,comment failed moderation?