Ian

I'll also +1 this - thank you guys, I never knew how the ± notation worked.

If you want privacy, I'd recommend the Motorola 900 MHz FHSS gear. It's obscure enough that nobody really uses it, proprietary enough that there's not any scanning hardware for it (to my knowledge), and if you feel clever you can get the old gear and run a mag-mount antenna. What do you need privacy for, anyway? Just don't want incessant, irrelevant chatter, or something?

https://amzn.to/2Hlpmpg Doesn't stop people from selling FRS radios as "license free" "business radios".

Samcom is offering some nice looking radios on Amazon that claim to be GMRS certified, and their featureset is rather compelling. Well, no it's not. It's the user interface that's compelling. It's got a large, clear, and backlit LCD. It can simultaneously watch two channels, or transmit on one or another using a face-mounted or side-mounted dual PTT system. Allegedly, the front PTT transmits on all the programmed channels simultaneously. Grabbing one of those simply so I only have to say "WRCH569, Monitoring" once is tempting, honestly. It's a mid-tier 20-channel radio with unclear FCC licensing data, but claims to radiate 4.95 watts with them, 3 watts on their website, and a whole bunch'o other useless information, but the half-inch high channel numbers, physical channel-change knob, and lockable all-of-the-buttons is kind of compelling for when you want to hand a radio to someone who struggles with anything as complicated as a Radius SP21.

Welcome to the community, WQYW694.

I just spent half an hour on the phone with Ritron's engineering department. Found out a few interesting things! Possibly the only hardware they got certified for GMRS was in Canada - the customer callbox, and the Jobcom base station. They don't know if those certifications are valid in the US, but I'm going to encourage them to get some handhelds certified. Their Liberty Repeater IS certified, and the guy who "owns" that project clocks out at 3:30. Four minutes before, and I'd have gotten to talk to him today, but as it stands I'll talk to him tomorrow. I'm interested in how the heck one hooks up a linear amp to one to bring it back up to 50 watts from two to five. Depending on what they can do with the duplexer, it may be my turnkey option of choice. The DTX telemetry radios and the base station do not, contrary to popular belief, share any hardware. … But they don't make any GMRS certified mobiles or handhelds.

Bluetooth speaker-mics are legal on the personal radio services, now, so it sounds like I'm good. Are you suggesting that the older DTR and DLR radios had SMA antenna connectors? Now I'm back to wanting a VHF/UHF/900 antenna for the truck, the house, &c. I can see some concern with unlicensed operators, but I really don't think it's a huge concern -- only place I've seen the DTRs is at the local YMCA, and I can pretty easily program a user and group ID that they don't use, on the off chance that I'm driving by there and am briefly in range while they're transmitting. I think this solves my "cheapish tiny portable repeater" problem pretty elegantly, though!

Also using a mag-mount on a cookie sheet right now to scan the simplex channels.

https://www.motorolasolutions.com/content/dam/msi/docs/products/two-way-radios/on-site-business-radios/dlr-application-briefs/dlr_spec_sheet.pdf Would it be legal to use a $10 cross-band-repeater cable with these ISM radios and GMRS? I can't see anything saying it's forbidden…

I own four of the Dakota Alert HTs, three or four of the base stations (three, I think), and a Radio Shack mobile MURS radio (that I haven't installed in the truck yet). They're not what I would call small -- though they mercifully use AA NiMH batteries, so you don't have to dismantle and repack the battery pack when they go bad. There's a VHF version of those tiny little things? That's perfect! I was looking at the Alinco DJ-C1 and its immediate successors, but they appear to be very scarce and expensive, and while they only do about 300 mW, that's fine across the house.

I'm thinking something about this size. Do they exist?

In the meantime, you might try CloudApp.

I'm reminded of this Reddit thread. Also, regarding balloons tailing behind me on the 417… Edited to add: Thank you for building a repeater that can be used by your neighbors in a pinch! Especially in a hurricane area, that's a potential lifeline.

Well, that's a gut punch.

Transportable != mobile. Compliance could be achieved by, for example, powering it from an external 120v circuit via extension cord, or a double-pole double-throw switch that disconnects the battery from the vehicle and prevents vehicle operation while the repeater is in operation. Tapping the signal line to the "BRAKE (!)" light on the dash to enable the repeater controller is yet a third option. This is an engineering problem, and it is fairly tractable. I may not have the patience to hack together the fanciest options, but running the gear off an extension cord should be quite simple, and would in fact allow me to locate the whole kit 'n caboodle in a truck tool box that can be moved, removed, or carried up a freight elevator if a rooftop is available and convenient. Exactly the edge-case I have in mind. Besides that, the balloon-lofted antenna in my hobby project simply cannot be deployed in motion, or you won't have a balloon-lofted antenna - or any antenna - very long. I was planning on something to support a local festival like the Highland games, and people enjoying themselves there. (PS, really don't use that thing around power lines, and especially high-tension lines. ) I'm working on it. But mostly this stuff is already available to amateurs, and does me absolutely zero good 'cause nobody else I know has, or is willing to, get an amateur license. If they give me a justification, it's either due to not being arsed to study, too much hassle, or perceived toxicity in the culture surrounding amateur radio. "Pushing forward the state of the art" as used here is really about improving the products available to customers via retail channels. Finding new handies that are repeater-capable is an exercise in scouring eBay for new old stock. I think the only products available are the TERA TR-505 and the BTECH GMRS-V1; the former requires PC programming and won't cover all the channels in the service, the latter requires … actually the BaoFeng meets spec IMHO. I mean, if nobody makes it yet, there's always Kickstarter… Not that I'll be ready for that until I have a few more years' experience under my belt, but I still really like the idea of a combination satnav and 50 watt GMRS radio.

Corey, the reason I'd like to play with solid-state filters is to push the state of the art forward. Cavities are perfectly serviceable, and I intend to use them in my first repeater. However, at some point I'd like to build a truck-mounted transportable repeater, and it doesn't have room for a 19" equipment rack. That means compromises in order to achieve acceptable performance and flexibility. Complexity gets me great performance - imagine a hydrogen balloon carrying the antenna, tethered to the truck bed by some G-line - but drives up the cost something fierce. It'd be a fun project, though, when I'm independently wealthy. In the meanwhile, I shall content myself with only a modest improvement in antenna height. Also, if I ever ended up with a lunchbox repeater like that, I'd be using an external linear amp to give it some respectable power output... ideally also a lunchbox form factor with an internal backup power supply. Berkinet, I've looked at tiny fifty-watt duplexers on Amazon (about fifty bucks) that would easily fit in a single-DIN car mounting. I suspect that's what the lunchbox repeater is using. Alas, cars these days don't tend to have any DIN mounts, let alone extras. I just can't afford the equipment to tune them myself, and I'm not sanguine about what I've heard about thermal drift on these things' calibration. In a perfect world, there'd be community repeaters I could borrow everywhere I go, but most of the time I'm somewhere where I can't reach 'em, though at home I can sometimes barely hear the two in the region. Jones, I do want an eight-channel repeater, and I want it cheap. Not for me, but for the future of our hobby and the service as a whole. If everybody could drop no more than $500 on a repeater and a cute little chimney-top tower, suburbia will be blanketed in community repeaters, and the utility and value of having a radio increases exponentially. Cost, complexity, and colocation will kill budding hobbyists' ambitions, and in the same way you say "just use simplex" hams tell me "just use a cellphone". I'd prefer not to be beholden to people whose business model includes AI-driven ad tracking and selling personal information; the competition will ultimately limit their options for screwing their customers over. If people put wi-fi on those community repeaters' cute little towers, many people could get by without any cell plan at all. I don't want to be the underutilized slice of UHF that gets sold to AT&T next... best way to avoid that, in my opinion, is to increase traffic and use until cell phone companies will look at the spectrum, sigh, and realize that even if they did buy it they'd never in their wildest dreams of enforcement success be able to stop all the people with walkie talkies from causing constant 5G blackouts, and won't be tempted to lobby for this. That's why I want an eight-channel repeater. Not for me, but for everybody.

Thank you! Apologies. I'll be operating under "Art's Grammaw" vocabulary from now on.

Fixed stations are also assumed to be those stations that only communicate with fixed stations; base stations are like fixed stations but intended to communicate with mobile units. It's assumed that fixed stations will be using tight-beam antennas, while base stations will be using omnidirectional antennae. The EIRP of the fixed station, even using only 15 watts, should probably be higher than the base station using an omni at the same range, so long as the beam antenna is pointed at you.

I have a Midland MXT275 and it's in a temporary mount. Eventually, I hope to mount it behind the dash, with one of these bad boys or maybe one of these with a mudflap. That's a very popular mounting method in Australia, since a lot of the UHF-CBs use 8p8c jacks for their handheld control heads. http://sti-co.com/covert/ I'd like to mount it with one of their dual-band fender-mount antennas; the intent is a really factory look with no sacrifices involved, or hole-drilling required.

Welcome to the hobby, WRCU244!

The colocation fee and lease is more or less similar to the data center environment you're used to. I'm in the same boat, as a newbie wanting a repeater, but that much I got out of a buddy who's building a repeater.

No! Now all I need is for Garmin to build a mobile GMRS/satnav combination, or to roll one myself.

At some level, this is a "Why can't we have nice things?" question. (What nice things, you may ask? These nice things.) But how hard would it be to find out who's using 452 and 472 MHz frequencies? Assigning them to GMRS, even on a secondary basis, gives us access to all-eight-channel-at-a-time, all-solid-state, no-oscilloscope-required repeaters. I believe the semiconductor filters used here could be improved to do 5 MHz splits, but that is clearly beyond the current state of the art (though military tech may be capable of it, they have priority access to whatever spectrum they require to do their jobs, so alternately it may simply have never been developed, though their budgets are quite up to the R&D task involved. https://en.wikipedia.org/wiki/Elliptic_filter I think that the Elliptic filter is the best approach to building solid-state GMRS repeaters. Chebyshev and Butterworth filters have better ripple characteristics, but Elliptic filters offer the sharpest cutoff available, and if the location of the ripple can be controlled adequately, a circuit board with reliable, repeatable and temperature-insensitive performance could be a duplexer. If Butterworth filters are capable of acceptable performance, however… A circuit board with reliable, repeatable and temperature-insensitive performance could be a duplexer for every channel, simultaneously. I've also looked into surface acoustic wave filters, which are doing the black magic in LTE base stations. They're almost certainly capable of the 5 MHz splits we need, but they also cost like black magic ought. A more compact repeater may be achievable, but a more affordable one? Not so much. So, I ask you, the brain trust -- what's easier, the bureaucratic burden of finding an underutilized slice of spectrum at least 10 MHz away from our little chunk of the UHF, or the engineering burden of figuring out if this XXXXXXXX is possible, and then making it a product?

They're marketed as "interference eliminator codes" in honest marketing. They offer no privacy, only solitude. If you want privacy, you want encryption and or FHSS… both are illegal in GMRS, but available in 900 MHz unlicensed radios that can do up to 1 watt. Motorola markets them heavily for business use, as the licensing requirement is … well, "no requirement" is very easy to comply with. They don't encrypt, but they do do FHSS, which makes them pretty low-probability-of-intercept.

Has the Rino protocol been reverse-engineered yet?