berkinet

Marc. Could you point to those posts. Specifically, did the FCC find the site to be in compliance, or the radio? Also, I would not take "not finding any issues" to be synonymous with "in compliance."

Well, yes, but... Since that filter costs anywhere from 2x to 9x the price of the CCR it would be used with, the money would probably just be better spent of buying a decent radio in the first place. Which is, I think, the point everyone is trying to make anyway.

YES! There seems to be sort of an obsession with power on GMRS. People debate over the 35 watt or the 40 watt version of some radio, and replace decently functioning connectors with silver plated N-Connectors, usable COAX with LMR400, in search of a 1:1 SWR and 0db loss in the antenna line heading to some absurdly expensive antenna with infinite gain. Yet, it is rare that someone asks about a radio's audio quality, and virtually nobody ever asks about receiver sensitivity or selectivity, etc. I suspect this is something GMRS inherited from CB where power is king and people slap an amplifier on anything. Both transmit, and receive (seems nobody ever mentioned that you can amplify signal strength but not signal quality, and amplification of zero remains zero). I really would like to see more concern for a good sounding radio that can meet the user's defined communication needs, rather than the biggest and best. Dream on...

If the cable or connectors between the radio and the meter are defective, that might account for the problem. How does the radio work on receive?

If by "Mini" you mean the BF-T1, it is listed as supported.

I use VirtualBox on MacOS to run any radio configuration software that does not run natively on the Mac, which is most vendor supplied, and have no issues whatsoever. It might be a bit of a challenge getting VirtualBox set up the first time. But, from then on it is a snap. The biggest problem is getting a copy of Windoze. Or, use CHIRP. Runs fine on MacOS and AFAIK works with all Baofengs. Even if your particular model is not listed, there is almost always a similar model that will work.

Or, put a radio on a test bench.

Given your SoCal location, I would go with the outside eave mount and then properly protect the coax.

...Or, did they change anything at all?

As explained above, you do not need CTCSS/DCS, etc. on receive. Try setting the receive frequency to carrier squelch, I.e. No PL, No DCS.

Note there is a difference between channel spacing, the frequency difference between the center frequency of two adjacent channels, and occupied bandwith, the amount of deviation of the signal around the center frequency.

So, essentially we are all too ignorant to read the FCC rules, which you state explicitly tell what is and isn't permissible. That seems to be a bit of a contradiction. Because, if we do stick to the rules, then they tell us, as noted previously, that the modulation (not Emissions Designator) cannot be changed. Explicitly, the rules prohibit: ...altering the amplitude, frequency and/or phase of a radio frequency carrier. However, the rules do not say the bandwidth cannot be changed. However, if we stick to your primary premises that we are too ignorant, and must let the commission decide anything and everything, then I would ask why there is absolutely no record of anybody ever having been cited for operation of non-certified equipment in the GMRS, let alone for modifying a GMRS radio? Is that not evidence of how the FCC views the use of non-certified and modified equipment? I personally believe the FCC provided the rules and regulations for a purpose, and that purpose was to guide operators and manufacturers in appropriate use of the different radio services. I would neither take it upon myself to assume something not stated in those regulations. And, finally, we live in a country with a well defined legal process. In a court of law, it is the regulations as written, plus any previous applicable court law that counts. The FCC's opinion is worth absolutely no more, and no less, than anyone else's opinion.

Except Part90 ≠ Part95. You have taken Part90 rules (47 CFR Chapter I - FEDERAL COMMUNICATIONS COMMISSION; Subchapter D - SAFETY AND SPECIAL RADIO SERVICES; PART 90 - PRIVATE LAND MOBILE RADIO SERVICES (§§ 90.1 - 90.1338)) and seek to apply them to Part95. While Parts 90 & 95 are both contained in Subchapter D, they are separate, independent and unrelated.

I have to go with @hans' well prepared and documented presentation on this issue. Further, I would like to add a point that, I believe, has been missed so far. In §95.337 there is a primary condition placed on the limitation of modifications: No person shall modify any Personal Radio Service transmitter in a way that ... ...operation of the modified transmitter results in a violation of the rules in this part. In this case, the term this part refers to Part95, Personal Radio Services. So, as long as a GMRS certified radio continues to transmit within the rules set forth in Subpart E - General Mobile Radio Service (§§ 95.1701 - 95.1793-95.1899), modifications would be permitted. Now, there is a separate limitation in that same paragraph that prohibits modification of the ...form of modulation. So, we need to know what the FCC means here by the term modulation. And we find that answer in: 47 CFR §95.303 Modulation. A process of altering the amplitude, frequency and/or phase of a radio frequency carrier wave generated within a Personal Radio Service transmitter, for the purpose of impressing onto the carrier wave information to be transmitted. This is distinctly different from the term Emissions Designator, which describes Bandwidth, Modulation Type, Modulation Nature, and Information Type. So, as long as the radio continues to transmit in compliance with §95.1775 GMRS modulation requirements, which authorize both narrow and wide band operation, changes in bandwidth alone would be acceptable. And, finally, all else aside, if a radio is modified by programming solely to alter the received PL, etc. settings, such modifications would not affect the transmitter and would be completely permissible. So, in conclusion, based on @hans' posts and the information included here, I now have to say I believe @marcspaz's original contention that modification to transmit bandwidth, and in fact any modification at all, was incorrect. I contend that any modifications that do not cause a certified GMRS transmitter to operate outside the rules stated in Part 95E, are allowed.

If the radio is GMRS certified, it is possible you have some memory locations that cannot be programmed for repeaters. What radio are you trying to program?

NSFW = Not Suitable For Work. non-radio

No question about that. I only noted that radio in response to Hans’ question about whether it could do 20 kHz wideband.

@Marcspaz noted that the MXT400 was only certified for NB in an earlier post. So, I think it is clear that setting that radio to WB would violate certification. However, the Luiton LT-590 (which you first identified as the same radio) does seem to allow setting bandwidth to 12.5, 20 & 25 kHz. That is, the software provides the option. I have no idea if it actually works. See this post upthread in this topic.

Are you sure of this? Perhaps I misread your post. I would think that if the manufacturer (or whoever is getting the radio certified) included the capability to configure elements of the radios via software, and documented those capabilities in the certification application, that doing so would be Ok. Note in particular the Kenwood GMRS radios that have keypad programming locked out but can be programmed with the appropriate software. Of course, programming would not include changes that would not be allowed in GMRS, like transmission on non-GMRS frequencies, power and bandwidth settings > the FCC specified limits for a channel, etc. However, organizing memory locations and banks, setting PL, etc. and audio signaling, adding text labels, roger-beeps (though those should be categorically outlawed!), etc. would all seem to be things that can be changed by the end user without voiding the certification.

Just curious. Why not put the duplexer in with the radios, even if it means a bigger box. You could use small size coax like rg214 with no concerns about loss, but increased flexibility. Then, you could make up sets of 2-conductor power cord with power-pole connectors - and use as many/few as necessary, and locate the radio box way up in a tree if you wanted. You could also put both batteries in with the charge controller for better use of space.

It is going to be, at best, difficult getting the separation you want while keeping your cable runs (and now I2R losses) low. So, if you are willing to risk $20 by taking a chance at blowing up your radio, why not just spend a little more and get a cheap UHF duplexer? That way you can put Tx, Rx & the antenna in one box and the power supply elsewhere, connected with low-cost #12 or #10 wire.

All well there. But, do you realize that same information was posted to this MyGMRS in this same thread back in July?

Note that with your design you will be sending both charging current and operating current across the cable. I would suggest you look for a multipurpose cable which actually combines a copper pair (for DC) and a coax. these could be in the same jacket or fused along their length. If you can’t find something you like, then I’d suggest using a small diameter plastic conduit or tube with DC and coax inside it. BTW, since it appears you will not be using a duplexer, how do you plan to get enough isolation between the rx and tx antennae?

I thought you had a DB420 and at some point we’re thinking about stacking them?

Don’t worry too much. Any cable that works is just fine. There is no such thing as one cable working better than another. However, there are some cables that just plain don’t work. Though, even with them the problem is usually with the USB chip drivers on the PC and not the cables themselves. In general, the cables with FTDI chips seem to me more reliable. The Prolific chips are fine as well. However, unfortunately there are a lot of counterfeit Prolific chips in the market and they won’t work with the standard Prolific drivers. Note that Bluemax49ers sells cables with both chip sets, though the FTDI are usually more expensive.