Trying to better understand modified/homebrew/out of band/etc

Yes, I know...beat to death...search...all that. I did, and I'm likely just not searching with the correct terms.

Also, I'm NOT ARGUING the point, just trying to get a better understanding

From the "out of band" sticky -

The reason that radios need to be certified for Part 90 for public service bands is to be sure the radio does not put out spurious emissions. Ham radio gear is designed by the manufacturer to only be used in the ham bands. The circuits and final output is designed to only be used within a certain spread of frequencies. When you start using frequencies that the radio isn't designed for there are unknown issues. Out of band, spurious emissions can come from the radio on frequencies other than the one you're transmitting on. Your radio display may say 155.000 MHz but you could be putting out several watts of power on 158.000 MHz, or 138.000 or 154.500, or anywhere else, which could cause intereference to other users and services. The Part 90 certification ensures that the radio is up to specs within the designed frequencies and ensures that the radio isn't causing harmful interference.

The Wouxun and Baofeng radios are technically Part 90 radios that are also marketed as ham rigs. No other ham gear (that I know of) has Part 90 or Part 95 acceptance.

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I 100%, completely, understand the technical aspect of spurious emissions and the like when going outside of the band the radio was designed for. I 100% understand the Part X acceptances, and why the non ham radios need to have Part X acceptance for use on their intended bands. I understand that ham radios aren't Part X accepted, and that we can home brew equipment. Or...maybe I don't understand them at all, and that's my problem

I believe I understand that if I take, say, a random Yaesu 2 meter radio and modify it for use on the public service band around 150Mhz, it may cause undesired interference on that band, potentially the 2 meter band, and even bands that aren't even close to those frequencies, and that's why I can't modify ham radios to work on non ham bands. Makes perfect sense.

Where I believe my failure to understand is that isn't that the same deal if I home brew a 2 meter radio, and use it on 2 meters? After all, we are "amateurs" here, not necessarily professionals. If I don't fully understand what I'm doing when designing/building/tuning a radio I built from scratch, aren't I still potentially going to cause that same undesired interference on 150 or 138 or whatever, despite being "legal" in what I'm doing?

Again, I'm not trying to argue that I/we should be able to use modified ham gear on other bands, but rather just trying to better understand the why of the regulations.

That's a valid question, and I'm replying mostly so I can read what I'm sure will be a lot of interesting comments.

Here's the part from Part 97 (Amateur rules) that would sort of apply:

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§97.101 General standards.
(a) In all respects not specifically covered by FCC Rules each amateur station must be operated in accordance with good engineering and good amateur practice.

(b) Each station licensee and each control operator must cooperate in selecting transmitting channels and in making the most effective use of the amateur service frequencies. No frequency will be assigned for the exclusive use of any station.

(c) At all times and on all frequencies, each control operator must give priority to stations providing emergency communications, except to stations transmitting communications for training drills and tests in RACES.

(d) No amateur operator shall willfully or maliciously interfere with or cause interference to any radio communication or signal.
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"Good amateur practice" would suggest that an amateur should know enough to do things correctly. That would include designing and building their own equipment with enough forethought to not cause undue interference outside the amateur bands.

"(d) No amateur operator shall willfully or maliciously interfere with or cause interference to any radio communication or signal."

Willfully or maliciously interfere. That would suggest that modifying a radio knowing it can cause interference would be wrong, as in willfully doing it knowing amateurs are not supposed to. Obviously there are some catches here, like those that modified radios to access the 60M band.

Some other rules that could apply. I'll avoid cut-n-pasting the crap out of them and let you look them up for yourself:
§97.121 Restricted operation.
§97.307 Emission standards. -- very appropriate for the question you are asking --


The important thing to remember is that while this is considered an "amateur" service, it does not absolve a licensee from any responsibility. Willfully modifying a radio against the FCC rules and violating it's type certification is documented as against the rules. Knowingly doing this would put your license in jeopardy. Building your own radio and taking the necessary steps to reduce out of band emissions is a requirement. If you didn't, the rules say they can shut you down.
The privilege comes with responsibilities.

mmckenna said:

The important thing to remember is that while this is considered an "amateur" service, it does not absolve a licensee from any responsibility. Willfully modifying a radio against the FCC rules and violating it's type certification is documented as against the rules. Knowingly doing this would put your license in jeopardy. Building your own radio and taking the necessary steps to reduce out of band emissions is a requirement. If you didn't, the rules say they can shut you down.
The privilege comes with responsibilities.

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Very true, and this is one of the biggest reasons I've shyed away from modifying non ham radios for use on the ham bands. Years prior I played with adjusting a couple Bendix-King VHF radios for use on 2 meters, and while I got them to the point of being able to transmit on 146.xxx, I always felt like I more or less just got lucky on the tuning pots, but didn't have the test equipment or the knowledge to being able to say 100% that I wasn't causing an issue somewhere else. But from my understanding of the rules, I was still "legal" in what I was doing, and would be OK with using it on the ham bands as is.

Another example of this would also be the poster I saw playing with the spark-gap transmitter. While his neighbors may not appreciate what he was doing, it seems as if he's "legal" in doing so.

62Scout said:

Very true, and this is one of the biggest reasons I've shyed away from modifying non ham radios for use on the ham bands. Years prior I played with adjusting a couple Bendix-King VHF radios for use on 2 meters, and while I got them to the point of being able to transmit on 146.xxx, I always felt like I more or less just got lucky on the tuning pots, but didn't have the test equipment or the knowledge to being able to say 100% that I wasn't causing an issue somewhere else. But from my understanding of the rules, I was still "legal" in what I was doing, and would be OK with using it on the ham bands as is.

Another example of this would also be the poster I saw playing with the spark-gap transmitter. While his neighbors may not appreciate what he was doing, it seems as if he's "legal" in doing so.

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Exactly. Since amateurs do not require type acceptance on the transmitters, it's OK to do that. Same with receivers, but often/usually/always you might see that the receiver portion of many amateur radios -do- have a part 15 certification.
Lots of us using commercial gear on amateur. Most repeaters are probably running commercial gear. None the less, modifying the commercial gear to work outside it's designed coverage would technically be modifying the radio and void it's Part 90 type certification, so using it outside the amateur bands would seem to be against the rules -after- the modification. Good news is that a lot of the newer commercial VHF gear covers 2 meters pretty well out of the box.

Yeah, spark gap transmitters, not a way to make lots of friends. Although I will add that my grandfather lived across the street from a park. Back in the early 70's a lot of young kids would hang out at the park with their AM radios blasting. My grandfather chose to build himself a small spark gap transmitter from and old automotive ignition coil. He'd hook up to a ground and the rain gutters and wipe out broadcast AM radio for a few block radius just long enough to run the kids off. Totally illegal, totally against the rules and I'm sure annoyed a fair number of neighbors, still funny to watch.

I will copy and past 97.307 because it is very relevant to this conversation.

§97.307 Emission standards.

(b) Emissions resulting from modulation must be confined to the band or segment available to the control operator. Emissions outside the necessary bandwidth must not cause splatter or keyclick interference to operations on adjacent frequencies.

(c) All spurious emissions from a station transmitter must be reduced to the greatest extent practicable. If any spurious emission, including chassis or power line radiation, causes harmful interference to the reception of another radio station, the licensee of the interfering amateur station is required to take steps to eliminate the interference, in accordance with good engineering practice.

(d) For transmitters installed after January 1, 2003, the mean power of any spurious emission from a station transmitter or external RF power amplifier transmitting on a frequency below 30 MHz must be at least 43 dB below the mean power of the fundamental emission. For transmitters installed on or before January 1, 2003, the mean power of any spurious emission from a station transmitter or external RF power amplifier transmitting on a frequency below 30 MHz must not exceed 50 mW and must be at least 40 dB below the mean power of the fundamental emission. For a transmitter of mean power less than 5 W installed on or before January 1, 2003, the attenuation must be at least 30 dB. A transmitter built before April 15, 1977, or first marketed before January 1, 1978, is exempt from this requirement.

(e) The mean power of any spurious emission from a station transmitter or external RF power amplifier transmitting on a frequency between 30-225 MHz must be at least 60 dB below the mean power of the fundamental. For a transmitter having a mean power of 25 W or less, the mean power of any spurious emission supplied to the antenna transmission line must not exceed 25 µW and must be at least 40 dB below the mean power of the fundamental emission, but need not be reduced below the power of 10 µW. A transmitter built before April 15, 1977, or first marketed before January 1, 1978, is exempt from this requirement.

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Yes, you are allowed to home-brew your radio for the Amateur Radio Service. But, even if you home-brew, your radio still must comply with the technical standards contained in Part 97.

If you go back to the November 2015 issue of QST, you'll find an article where the ARRL tech editors raise the issue of certain commercially-sold radios that have been found to violate 97.307.

So basically, it would appear that I did not, in fact, fully understand the Part acceptances. Particularly where it would involve the modification or building home made radios, in that I hadn't yet seen the parts that involved specific limits on emissions standards. I did know that it was on me to take reasonable steps to eliminate, or at least reduce as much as possible, unintended interference, but didn't realize the specific limits noted above.

Somewhat related, I'm now also beginning to get a better understanding of why some of the long term ham guys are less than pleased with the "dumbing down" of the FCC test to become licensed amateurs. Not that I'm saying I agree, or disagree, with it, but it does seem like this is the kind of thing that should have been covered even in the tech license requirements....which is an odd feeling, given that I passed the tech exam with flying colors, yet wasn't aware of this stuff until today...

Yeah, that's a good point. I got my amateur license back in the late 80's early 90's. The test seemed harder back then than it is now. I could be wrong. I know I had to do a lot of studying to learn all the subject material. Back then there were still vacuum tube related questions on the test, but I'm sure there are amateurs that have been licensed longer that could put that to shame. I work with a guy who's been an amateur long enough that when he originally took his test he had to do it at the FCC office.

On the flip side, my wife did a one day "Ham Cram" session where she basically walked in knowing little about radio and walk out with her certificate of completion. Total of about 6 hours. She learned how to regurgitate answers, not really know anything about radio. Still, she has her license.

Probably the way to look at it is that the license gives you the permission to get on the bands and continue learning. I think what the old timers actually resent is those that pass the test then think that's it. Like most things, it's an ongoing learning process.

Also, I think the FCC rules should play more into the testing process. Not just Part 97, but Part 2, Part 15, etc. I see too many issues where it's obvious the licensee knows little or nothing about the rules they are operating under.

mmckenna said:

Also, I think the FCC rules should play more into the testing process. Not just Part 97, but Part 2, Part 15, etc. I see too many issues where it's obvious the licensee knows little or nothing about the rules they are operating under.

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Heck, I think it could be successfully argued that _I_ am one of those people now...perhaps that's why I've also felt like I was taking a heck of a backlash when I was asking other questions on trying to understand situations better...it could have been seen as things that I should have already known as a licensed radio operator....(in my post history there will be a question on trying to better understand why my 11meter antenna wasn't measuring the way I expected it to, and the responses I got from a local ham forum nearly caused me to lose interest in ham radio altogether).

I definitely have some more studying to do

62Scout said:

(in my post history there will be a question on trying to better understand why my 11meter antenna wasn't measuring the way I expected it to, and the responses I got from a local ham forum nearly caused me to lose interest in ham radio altogether).

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My own limited opinion is that Amateur radio operators are the biggest problem with Amateur radio. Elitist attitudes, poor social skills, bad manners. It's not a widespread issue, but unfortunately those that have this problem are often the loudest.

A great resource:
https://www.fcc.gov/general/rules-regulations-title-47
It's not written in easy to understand words. Some of it is disjointed and contradicting in certain places. Some sections of the FCC rules are in dire need of a rewrite. None the less, it's what we've got to work with.
Part 97, in it's entirety would be a good read.
Part 95, applying to CB, FRS, GMRS, MURS and a few others would be a useful bunch of knowledge.
Part 2 should be read well, it applies to all services, including amateur.

If you aren't asleep yet after reading all that, Part 90 can be helpful, especially those in the scanner community.

This is one reason I run commercial (Motorola) gear. It's also all newer radio. I also own calibrated test equipment (Motorola service monitor) so I can know that my equipment is working how its supposed to be.

I also use Part 90 frequencies. So I need radios that will play there legally. Some of the stuff I do is on trunking so that's another reason why I need radios from mother M.

To me the cost of the commercial radios and their abilities, even on the ham bands, is worth the cost. They work great in the ham bands and work great in Part 90 land.

To go back to your question, as others have said, if you modify/build equipment it's up to you to make sure its staying within the rules.

The situation reminds me of the snake eating its own tail. Ham A, who feels he is still fairly ignorant with respect to some aspect of radio, decides to ask other hams about it. Ham B, equally ignorant but highly opinionated, provides answers to Ham A, who now knows just as little as he did before, but believes otherwise.

62Scout said:

So basically, it would appear that I did not, in fact, fully understand the Part acceptances. Particularly where it would involve the modification or building home made radios, in that I hadn't yet seen the parts that involved specific limits on emissions standards. I did know that it was on me to take reasonable steps to eliminate, or at least reduce as much as possible, unintended interference, but didn't realize the specific limits noted above.

Somewhat related, I'm now also beginning to get a better understanding of why some of the long term ham guys are less than pleased with the "dumbing down" of the FCC test to become licensed amateurs. Not that I'm saying I agree, or disagree, with it, but it does seem like this is the kind of thing that should have been covered even in the tech license requirements....which is an odd feeling, given that I passed the tech exam with flying colors, yet wasn't aware of this stuff until today...

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This s why it is important to learn in a classroom setting from hams who have been in the service for a while. Rather than from online resources.
All good answers have been given in this thread. But, realizing that you don't know much about amateur radio, is a good reason to find a local club and learn by listening and asking questions.
The interaction with those who are in your community is also rewarding
Larry

One point I didn't see mentioned with regard to the question posed:

The amateur bands aren't normally considered "mission critical". If a HAM builds or modifies a radio and it transmits garbage, he's bound to tick off his fellow HAMS around the band. Assuming he is conscientious and astute enough, he'll be called out soon enough and will stop transmitting as soon as he is told he's causing trouble.

In the other license classes, where the user is theoretically less radio savvy, a better quality radio is needed to make up for the user's deficiencies. Furthermore, especially were public safety (and operator safety) is concerned, there is an even greater requirement for a radio that meets the highest of standards.

bharvey2 said:

One point I didn't see mentioned with regard to the question posed:

The amateur bands aren't normally considered "mission critical". If a HAM builds or modifies a radio and it transmits garbage, he's bound to tick off his fellow HAMS around the band. Assuming he is conscientious and astute enough, he'll be called out soon enough and will stop transmitting as soon as he is told he's causing trouble.

In the other license classes, where the user is theoretically less radio savvy, a better quality radio is needed to make up for the user's deficiencies. Furthermore, especially were public safety (and operator safety) is concerned, there is an even greater requirement for a radio that meets the highest of standards.

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Yeah, that's partially true, however there isn't anything to keep rf energy neatly confined to the amateur radio bands. Often intermod, and a number of other issues can spread crap around well outside the ham bands.

Very true. The case in point was your grandfather's use of a spark gap transmitter for crowd control or CB hash on the TV bands. The FCC regulations can only go so far though.

62Scout said:

Heck, I think it could be successfully argued that _I_ am one of those people now...perhaps that's why I've also felt like I was taking a heck of a backlash when I was asking other questions on trying to understand situations better...it could have been seen as things that I should have already known as a licensed radio operator....(in my post history there will be a question on trying to better understand why my 11meter antenna wasn't measuring the way I expected it to, and the responses I got from a local ham forum nearly caused me to lose interest in ham radio altogether).

I definitely have some more studying to do

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N8IAA said:

This s why it is important to learn in a classroom setting from hams who have been in the service for a while. Rather than from online resources.
All good answers have been given in this thread. But, realizing that you don't know much about amateur radio, is a good reason to find a local club and learn by listening and asking questions.
The interaction with those who are in your community is also rewarding
Larry

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Could not agree more! Identifying and MEETING with local hams has helped me immensely in understanding all that I have studied about so far.

For me identifying my nearest club and ARES group, checking into nets and putting my call out there, so folks can start becoming familiar with me are good things I did that helped me meet local hams. I even went so far as identifying a local ham and calling him on the phone cold turkey and introducing myself to him. Worked out great, attended my county's ARES meeting which he is the head of and we will be attending our nearest radio club meeting together in a few weeks.

As far as further knowledge, I personally have decided I will be trying to identify an Extra classroom course when I am ready to earn my upgrade. The books and the online stuff has gotten me this far, but to be honest, I feel as I have learned the bare minimum to operate and actually consider myself to be clueless in much of the very aspects I am licensed for.

As far as new hams in general and what not, it seems to me everyone gets into the hobby for different reasons. But the ones that perplex me are the guys that get licensed and do not seek contact with other hams....whether its on the air or through meetings. For example, there was one guy on here awhile back that stated he had his ticket for several years and had yet to key a mic.....

Scout, don't be shy about asking questions, I am right there with you in having a lot of studying to do. I just plan on using actual people to learn and study from, instead of just books and the internet from this point forward.

Good luck!

KE0GXN said:

As far as new hams in general and what not, it seems to me everyone gets into the hobby for different reasons. But the ones that perplex me are the guys that get licensed and do not seek contact with other hams....whether its on the air or through meetings. For example, there was one guy on here awhile back that stated he had his ticket for several years and had yet to key a mic.....

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I've got a guy that works for me like that. Many years ago he was going to buy a scanner to listen in on the races at Laguna Seca. He was pricing out scanners and noticed he could buy a basic dual band amateur transceiver for about the same price as a new scanner. Myself and another guy here in the office are amateurs, so we got talking about it. He decided to take his tech test, passed, bought the radio for listening in on the races and has never once keyed up. Not sure if he even remembers his call sign.

mmckenna said:

I've got a guy that works for me like that. Many years ago he was going to buy a scanner to listen in on the races at Laguna Seca. He was pricing out scanners and noticed he could buy a basic dual band amateur transceiver for about the same price as a new scanner. Myself and another guy here in the office are amateurs, so we got talking about it. He decided to take his tech test, passed, bought the radio for listening in on the races and has never once keyed up. Not sure if he even remembers his call sign.

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. There are many people who simply want the license " under their belt" in case they feel the need to transmit. I have some neighbors who are railfans and only talk on murs, yet they are licensed hams. I've been licensed for years, but you'll only hear me on 2 meter simplex, 220 or 440mhz. since I don't care for hf. We all have our preferences ... :wink: 73,n9zas

mmckenna said:

I've got a guy that works for me like that. Many years ago he was going to buy a scanner to listen in on the races at Laguna Seca. He was pricing out scanners and noticed he could buy a basic dual band amateur transceiver for about the same price as a new scanner. Myself and another guy here in the office are amateurs, so we got talking about it. He decided to take his tech test, passed, bought the radio for listening in on the races and has never once keyed up. Not sure if he even remembers his call sign.

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I can understand the guys that just get a Tech ticket and talk on that and are happy with that. The ones that get a ticket and never press the PTT button or send a CW signal out are the ones that confuse me.

Sounds like your friend just needed to get the scanner instead....

One interesting point I would like to point out that most of the ham bands are multiples of the lower frequencies. Some where back int the dark ages, the FCC managed to at least try to do something that just might be considered practical. That was lay out the ham frequencies to be close to a multiple of the lower band like I have already said.

So if you were on 40 meters and had a second harmonic, it would fall close to the 15 meter band. Then if you were on the 15 meter band, the second harmonic would fall close on the 10 meter band. The 3rd harmonic of the 40 meter band would fall close to the 20 meter band.

But over the years, additional bands have been added and the sort of protection provided by this older method went out the door.

Being one of those who like to play with radios and modify what they do and change the frequencies they work on, I am luck to have test equipment to look at the output of the transmitter. Most of the new hams today are lucky to have a RF watt meter that provides a true transmitter output measurement. In my early days of experimenting with modifying radios, I was lucky to find a mentor to work with me and teach me some of the neat things about test equipment . He also taught me some of the internal workings of just how the radios work and how to fix them.

For the new comers to the hobby, I can suggest that you find a local ham club and go to some of their meetings. It won't be long before you will learn who the technical people are. Bite your pride and walk up to them and introduce yourself. Somewhere along the line of breaking the ice, you will find that these technical people don't bit, they won't yell at you, but they will expect that you will try to learn from them. You might even be taken under their wing and the just might become a mentor to you.

My original mentor that I met right after I got out of the army back in 1968 is still a very close friend. His health is declining, but we still chat via email and occasionally via the twisted pair. We became very close friends in a short time. We both learned from each other over the years.

Bottom line here, you can learn the hard way via the school of hard knocks, or you can saddle up with a mentor and be on the fast road to learning. What it took your mentor years to learn about radios, that person can show you in a matter of months. It may take longer for it all to sink in and make sense, but it's much faster than doing it on your own.

I have sort of got off the main topic of this thread, but wanted to point out that you may be new to ham radio and don't understand many of the reasons why there are restrictions in some places and your allowed to do almost what you want in others. You may not understand why people on here tell you that you should be careful modifying any radio your playing with.

Find a mentor to work with you and things should start falling into place much easier.

Sorry for being long winded. I was you some 55 years ago.

These days I work around public safety radio systems in many parts of the country. I still find it hard to swallow why some things are so screwed up in these systems. So don't think it's just here in the ham radio sector.