What does MARS have to do with Amateur Radio?

Foundations of Amateur Radio

In my travels along the highways and byways of the Internet I came across several references to MARS in relation to Amateur Radio. Being the curious soul that I am, my interest was sparked. I must warn you, today there is a lot to cover.

First up before I tell you anything, let me start by pointing out that what I'm talking about has different levels of application depending on where you are on the planet. I also need to inform you that in some parts of the globe this is considered illegal, where in other parts of the same globe, it's perfectly fine.

So, MARS, or MARS/CAP if you want to get more precise. What is it, how does it work and what do you need to know about it?

MARS is an acronym for Military Auxiliary Radio System and CAP is an acronym for Civil Air Patrol.

Given that we don't have such things in Australia, this phenomenon relates to the United States of America where MARS/CAP is used to coordinate search activities and relay messages on HF and VHF frequencies near Amateur Bands. As an interested party you can join up, do training and participate.

That aside, the term MARS/CAP is more widely referred to as a way of modifying your radio to allow it to access to frequencies outside the Amateur Bands. Now at this point if you're a licensed Amateur your ears should have pricked up when you heard the words "modifying your radio" and "outside the Amateur Bands". This is as I already said, legal in some parts of the globe and not in other parts.

So, a MARS/CAP modification extends the frequency coverage of your radio. Some modifications involve extending what frequencies you can receive, others extend the transmit frequencies. Often these changes are separate, but not always, so make yourself aware of what you're doing before you do anything.

Now why am I telling you about something that some might consider shady or illegal? First of all, I've not actually told you what to do or how to do it. Second, if you're trawling through the Internet and you come across such a thing, how would you know what it means in your situation, other than a list of instructions shown on some random website?

There are several different aspects to this. As I mentioned, the legal aspect which I'll discuss a little more later. There's also the technical, performance and warranty aspects to consider. Not to mention, emergencies and other exceptions.

From a technical perspective, there are generally two types of MARS/CAP modifications. There are hardware ones where you pull out your soldering iron and modify the circuit on your radio by adding or removing something. There are also software modifications where updating the version of the software on your radio, or changing a flag, or setting a memory will make the modification. The hardware changes are generally pretty permanent, the software ones are often able to be reverted back to normal, but not always.

While I'm warning you, some radios when opened up reset their memories, so you may need to reprogram all those channels when you put it back together again.

Now, your Amateur Radio is a finely tuned animal. It's specifically configured to work within the specifications of the Amateur Bands and regulations and as you should know, there isn't a single piece of hardware that exists that isn't subject to the variation of its components. This means that if you compare two identical radios, the same batch, the same builder, they still are not identical. If you put them on a testing bench, you'll notice subtle differences. They'll be close, but not the same. Each one is specifically set with preferences, variable capacitors, inductors and resistors to respond just so, and meddling with the hardware or software can - and likely will - change this finely balanced piece of gear. If you're fiddling to fiddle, be aware that you might never get your radio back to the way it was before you changed it.

If you let the magic black smoke out of your radio and return it to the manufacturer for a warranty repair, be prepared for a rejection letter or a hefty bill if you make any modifications.

So, on the no side, there are lots of things to consider.

On the yes side, there are others.

In the case of an emergency all is forgiven. If you need to call an emergency on some random frequency, then that's fine, but make sure it's a real life threatening one. If that's the case, does that mean that you need to carry a soldering iron around or a computer with a piece of software to reprogram you radio when that emergency hits?

Another thing is that many Amateur Radios, including the one sitting on my go-kit, a Yaesu VX-7R has a receive range of 500 kHz to 1 GHz with a few little gaps to exclude some mobile phone frequencies. There is no need to do any modifications to receive anything, just to transmit.

There are many websites dedicated to MARS/CAP modifications and for some people these are perfectly fine, but you won't find much in the way of disclaimers on those sites, nor will you see much in the way of warnings. You might have just modified your radio because you're curious, or you might have thought about doing so. Now you know a little more about the implications.

I did say that I'd come back to the legal side before I finished.

Here's a curious thing.

Essentially for commercial radios, the radio is licensed and for Amateur Radio, it's the person. In Australia, if I have a commercial radio that is approved for use on specific commercial frequencies, it's perfectly legal to modify that radio to use it on Amateur frequencies. But if I have an Amateur radio, it's not legal to make it work on commercial frequencies.

If that doesn't make your head explode, here's another passing thought. If you have an entirely Software Defined Radio that's approved for use on commercial frequencies, then what's the difference between that and the same radio approved for Amateur radio use, if the only difference is limits on the user screen access?

My point is that the law hasn't yet caught up with radios that work on any frequency. When it does, it's likely that the almost arbitrary distinction between commercial radios and amateur radios will disappear and your Amateur License will determine what is allowed and what is not.

A burning question you might be left with is: "So, Onno, did you modify your radio?" and my answer to that is: "Nope". I don't know enough about what these changes will do to the actual performance of my radio, if it introduces crazy harmonics and how I'd test for that, nor do I know what the precise legal implications are for me personally.

What I do know is that much of this is never talked about, let alone debated with any level of professionalism and frankly I don't think that's good enough.

These modifications exist, sometimes they're trivial to do, but the community pushes the implications under the rug and says: "Don't look here, there be dragons."

I for one think that Amateur Radio should be leading the way in this discussion, not hiding from it.

I'm Onno VK6FLAB