MARS/CAP mods

[AK9R]

Since we seem to have several posts about doing "MARS/CAP" mods to various pieces of amateur radio equipment, let's address the general usefulness of these mods by discussing what radios are acceptable to MARS and CAP. Maybe this will help people make educated decisions about these mods.

CAP

The Civil Air Patrol has switched to narrow bandwidth, and mostly P25, for VHF communications and it seems that they require a high level of frequency stability for HF radios. CAP Headquarters publishes a list of approved radios for HF , VHF narrowband FM , and VHF P25. If the radio you are considering isn't on one of these lists, then it's not acceptable for use in CAP no matter how many mods you do to the radio.

This page has links to important documents, such as the NTIA Redbook, which covers radio usage on federal frequencies and links so you can search the CAP's determination about various types and brands of radios.

MARS

I ran into some roadblocks finding information about MARS radios and I welcome MARS members to reply with information about what radios are acceptable for MARS. I also welcome information about what bands and modes are typically used for MARS.

Finally, if you want to do the "MARS/CAP" mod to your radio just so you can transmit outside of the amateur radio bands, understand that your amateur radio license gives you no authorization to do so and you may be violating FCC rules by doing so with your modified equipment.

 

[K4EET]

Since we seem to have several posts about doing "MARS/CAP" mods to various pieces of amateur radio equipment, let's address the general usefulness of these mods by discussing what radios are acceptable to MARS and CAP. Maybe this will help people make educated decisions about these mods. <snip>

MARS

I ran into some roadblocks finding information about MARS radios and I welcome MARS members to reply with information about what radios are acceptable for MARS. <snip>

As a member of the Air Force Military Auxiliary Radio System (AFMARS) although currently on Leave of Absence (LoA), I can definitively say that we are a very disciplined organization. Hearing you say that "I ran into some roadblocks finding information about MARS radios" indicates to me that the training we receive when we first join AFMARS and the ongoing training that we receive throughout our volunteer service to AFMARS is working quite well as should be expected. AFMARS prides itself on operational readiness in all aspects.

I also welcome information about what bands and modes are typically used for MARS.

Again, as a member with AFMARS, our main website can be found at https://mars.af.mil on the Internet. There is a document under REFERENCE and then MARS GUIDE TO NEW MEMBERSHIP that briefly covers radio requirements on the right side of the homepage. See:

1.2.1.4 Station Requirements.​

1.2.2 VHF Requirements.​

While those two sections are very general, I would encourage anyone that is genuinely interested in joining AFMARS to reach out to the staff via the QUICK LINKS at the bottom of the homepage using the hypertext Contact Us. You will be put in contact with somebody that can answer your questions.

What I will say is this, there are quite a few pieces of Amateur Radio equipment that can be modified by firmware and/or hardware to operate on AFMARS frequencies. Likewise, many modes that AFMARS utilizes will also be compatible with existing amateur radio station equipment.

73, Dave

 

[AK9R]

Thanks, Dave.

A few key points from the document you referenced:

"...all HF radio equipment must have a frequency stability and tolerance of +/- 20 Hz as set by the NTIA"

"Unless specifically exempted from the NTIA requirement, all VHF equipment must not exceed a frequency deviation of +/- 2.5 kHz, and have a channel spacing of 12.5 kHz (or less)."

 

[W5lz]

I was in a different branch of MARS but the general requirements are exactly that, general. There are different requirements in each branch too. From what little was outlined here, those requirements have pretty well held constant, no big changes.

 

[jhooten]

Unless things have changed the various MARS branches do not set equipment requirements. They are bound by NTIA standards.

 

[Hit_Factor]

I think there is a large group of radio enthusiast who refer to the 'MARS/CAP Mod' simply to mean removing limits of the TX range set in the radio. Sometimes this involves de-soldering a component, installing a jumper, changing firmware settings, or installing 3rd party firmware. There may be other methods.

I might know many people who have opened up their radio TX. Maybe for GMRS, MURS, Marine, or LMR. I don't know anyone who is in MARS or CAP.

 

[W5lz]

"Opening up" a transmitter isn't illegal until you transmit, at least in this country.

 

[ecps92]

Depends on whose rules you read/follow.

For years anyone working on [Non Amateur Frequency] transceiver equipment needed to maintain a license [have not kept up with those rules, others will likely chime in] - so "Openning up" could violate rules as it is no longer just an Amateur Radio - but then we can go round n round on this and other topics 24/7

"Opening up" a transmitter isn't illegal until you transmit, at least in this country.

 

[mmckenna]

Depends on whose rules you read/follow.

For years anyone working on [Non Amateur Frequency] transceiver equipment needed to maintain a license [have not kept up with those rules, others will likely chime in] - so "Openning up" could violate rules as it is no longer just an Amateur Radio - but then we can go round n round on this and other topics 24/7

GROL for some things.

And then there's the "modification" of the radio that would void the Part 15 rules that mass produced amateur radios are certified under.

In other words, many assume that they are magically exempt from the rules, yet everyone else is required to toe the line.

 

[N4KVE]

Years ago ham radios would only TX, & RX in the ham band. If we wanted to listen to the commercial, or cellular freq‘s, we had to do the mod. But with radios now receiving from DC, to daylight, there’s no reason for the mars/cap mod.

 

[nd5y]

Who needs a commercial operator license?
See

Commercial Radio Operator License Program

Rule Part 47 C.F.R, Parts 13

www.fcc.gov

 

[mmckenna]

Who needs a commercial operator license?
See

Yeah, the commercial license is no longer required for most stuff.

 

[buddrousa]

I remember when I passed my 2nd class General in the late 70's it was a big thing I had to pass the 3rd Class (Radio DJ) first.

 

[cavmedic]

Out of curiosity, how has any of this actually affected your quality of life, or had a personal impact on you? Secondly, how do you know what frequency they are transmitting on, as they could very well have commercial frequencies licensed to them, and or be authorized to be there?

Are you one of those guys who yell at people who arent wearing a mask when you don't know if they have a medical condition that prevents them from wearing one ?

 

[AK9R]

Secondly, how do you know what frequency they are transmitting on, as they could very well have commercial frequencies licensed to them, and or be authorized to be there?

Unless the radio is FCC certified for operation on "commercial frequencies", it would be illegal to transmit on those frequencies whether the user is "authorized" or not.

A rather well-known online amateur radio dealer charges $35-50 to perform "MARS mods" on brand new radios before they ship them. I'm not saying they are doing anything illegal. But, they are extracting additional funds for a useless service. Useless in that the radio can't be legally used to transmit out of the amateur radio bands and isn't accepted for use on MARS or CAP.

 

[cavmedic]

Unless the radio is FCC certified for operation on "commercial frequencies", it would be illegal to transmit on those frequencies whether the user is "authorized" or not.

A rather well-known online amateur radio dealer charges $35-50 to perform "MARS mods" on brand new radios before they ship them. I'm not saying they are doing anything illegal. But, they are extracting additional funds for a useless service. Useless in that the radio can't be legally used to transmit out of the amateur radio bands and isn't accepted for use on MARS or CAP.

And this affects you how? Seriously question.

 

[buddrousa]

No different than pretending to be a PARAMEDIC ethics.

 

[cavmedic]

No different than pretending to be a PARAMEDIC ethics.

Well I don’t PRETEND to be a medic, I was a medic in the Army and my modified radio is part
90 AND and I have licensed frequencies , so no ethic issues here , if that’s what you are attempting to say. But if I wasn’t , how would that affect you other than you interjecting yourself into something

 

[buddrousa]

Because I am a ham/EMT-B nothing said about you. I also am against MODDED RADIOS on Public Service.

 

[mmckenna]

And this affects you how? Seriously question.

And it's a good question, and it deserves an answer.

First, allow me to point out that the burden isn't on everyone else to prove that someone ignoring the rules is causing issues. The FCC rules were established for some good reasons, and understanding what those reasons are would be good reading for any one using any radio service, including amateur radio, CB, GMRS, FRS, etc. The FCC has rules in each of those sections (as well as others that apply (Part 2, Part 15) that require radios to not cause harmful interference.

So, to answer your initial question...
Modifying a radio to work outside it's designed specifications runs the risk of spurious emissions generated by the transmitter from getting past filtering that is designed to suppress them. Those unwanted emissions can cause interference to other licensed users, and not just hams.
Adjusting the transmitter incorrectly can cause issues, too. Case in point:
There is a popular line of Motorola radios that hams like to use. They are pretty well known to be good radios, however if you turn the RF power down too low, they suddenly start acting erratic and generating signals outside where they are supposed to. Most would think that turning the RF power down would be a good thing. In this case, without the right equipment, a radio can easily cause interference to other users, including public safety users.
I've heard more than one, "No one is complaining, so it's OK!". Problem is, it's not. Just because someone isn't complaining about a crappy signal coming out of your radio may just mean they haven't tracked you down yet.

I had to spend quite a bit of time earlier this year chasing down a transmitter that was interfering with one of our repeater inputs. It took a lot of time, effort and -taxpayer dollars-. The guys running the radio just assumed everything was OK, until I had to go talk to them. They'd be running along for months assuming all was OK. Meantime, they were wiping out one of our repeater inputs and I was driving all over trying to DF them.

So, that instance, it -DID- affect me. '

And this isn't an isolated case. I'm sure there are others on here that have gone through the same thing. The FCC has lots of documented cases of this, including stupid things like non-type accepted LED signs that were killing public safety radio coverage. You can look those up on the FCC enforcement bureau page.

So, this is why the FCC rules exist. Problem is there are those that think the rules are just a joke and don't apply to them. Yeah, often people get away with it and don't have any issues, but it doesn't mean it's NOT causing issues for someone.