SteveShannon

Great example! Thanks!

Unless the gain of the antenna and the height combine to create poor reception area near the ground close to the antenna.

That does help! Thanks!

There is no set limit specifically for GMRS HTs as far as I can tell. They might inherit the 50 watt limit of mobile stations. But I agree with @KAF6045that SAR exposure limits would create a practical limit. In reading through an ARRL article about exposure limits, 5.3 (I think) watts is the calculated max power for a 70 cm handheld in order to maintain a safe exposure level.

Rather than using the screen, it’s much easier for me (with my NanoVNA) to use the PC based software (VNASaver). The screens are separate and the controls seem easier and more intuitive to use, at least for me. I absolutely agree that you must turn off all the displays that you don’t need, like the Smith chart, etc. Also, keep the bandwidth as narrow as possible. Those jumbled mess traces with sharp inflections and straight nearly vertical traces are typical when viewing too much bandwidth at a time. They’re a product of the fact that you have relatively few points (501 in your case it appears) being displayed, so the VNA simply draws straight lines between them. Viewing all the way from 462 to 468 MHz is much wider than you want. Instead, limit the width to 500KHz above and below the frequency you’re concentrating on. Depending on what you’re measuring that may even be unnecessarily wide. Good luck!

I think you’re probably right.

No, you don’t have to program a receive tone. If you leave it blank you receive everything transmitted on that frequency. I usually recommend leaving the receive tone empty until everything else is working.

I agree that there seems to be a section missing, but you’re wrong in your interpretation. 95.1767 doesn’t enable station types; it creates power limitations, and it neglected to establish limits for handhelds on the main channels, unless handhelds are covered as a subset of mobile stations, which isn’t consistent with how handhelds are listed in the other sections in 95.1767. The section on channels (95.1763? I’m away from the computer) is where station types are allowed on specific channels. Handhelds are listed there for the main channels, as I recall.

To make it easier to discuss, rather than a screenshot here are the regulations: Each regulation only means what it says, nothing more and nothing less. The limitation 95.1767(b) for the 462 interstitial channels, only applies to stations transmitting on the interstitial 462 channels. Likewise, limitation 95.1767(c) only applies to stations transmitting on the 467 interstitial channels. Nothing about those limits extends to the other two sets of frequencies (462 MHz main and 467 MHz main). Rules just are not written like that. Neither does the lack of a listing for a power limit for a Hand-held Portable cause the lower limits listed in 95.1767(b) to apply to 95.1767(a)(1). If it did that would be very tricky to determine whether to use the 0.5 w ERP limit of 95.1767(c) or the 5 w ERP limit of 95.1767(b). The fact is, no output power is specified for hand-held portable stations in 95.1767(a) unless you consider a hand-held portable as a subset of the mobile category, in which case 95.1767(a)(1) applies, limiting a hand-held portable to the same limit as a mobile. To me that doesn't seem right. Now therre may be a higher level regulation somewhere that limits ALL hand-held transcievers to a 5 watt limit; I just don't know. The definition of a Hand-held Portable may support that. From Subpart A: Hand-held portable unit. A physically small mobile station that can be operated while being held in the operator's hand. So, I still haven't seen a rule or regulation in part 95E that limits the output power (which is not the same as ERP) of a hand-held portable in the GMRS service to 5 watts. I'm convinced I'm simply missing something, but the explanation you propose doesn't seem right to me.

Re the first question on small coax: Because it’s cheap and they’re relatively short cables.

I believe that's probably the case, but I'm having trouble trying to find something in the regulations that limits handheld portable radios to 5 watts for GMRS. I know that for the 462 interstitial channels there's a limit (as quoted below), but like I say, I'm having trouble finding the part of the regulations that limits all GMRS handhelds to 5w.: 462 MHz interstitial channels. The effective radiated power (ERP) of mobile, hand-held portable and base stations transmitting on the 462 MHz interstitial channels must not exceed 5 Watts.

I dealt with them in the early 2000s. Their stock went from $4 to $44 and then they were acquired. Although their CAD-CAM market share disappeared their Utility AM-FM business still does well. That’s the system I worked on.

I agree with KAF6045; make sure you know how to sweep the antenna first and that you see something that makes sense to you. Then sweep the antenna using the other port on the analyzer to make sure you're seeing the same results on both. Only after you have confidence in the analyzer and your ability to analyze an antenna will you feel comfortable performing a two port analysis of a filter or one side of the duplexer.

The most common type of PL tone is also called CTCSS. There’s also DCS To determine it you ask a repeater owner or you can scan for it with some devices.

I was project manager and programmer on an Intergraph FRAMME system between 1999 and 2005. Ours was PC based but I spent many hours working with folks in Huntsville that you might have known.

I see what you did there … ?

I don’t know if you watched these videos but Randy (@OffroaderX) discusses some of these things:

@OffroaderX discusses the desense issue in one of the (Notarubicon) videos he did about building a KG1000G based repeater.

It looks like you posted this question in two different places. I responded in the other.

They probably cannot be that close together. The receiver will desense. Also, how are you separating the transmitter signal from the receiver signal? Are you using two different antennas or a duplexer? If two antennas how much separation do you have?

The 2 meter repeater here probably has one or two conversations that last a few minutes each day, until our club holds a net each week, when it has to transmit for 15 to 20 minutes nearly continuously. So except during that time duty cycle is not crucial, but it it weren’t able to transmit continuously at least 20 minutes it wouldn’t be useful for emergencies. For a family repeater I agree with you, it’ll be very short transmissions with lots of cooling in between. For that matter, with the KG1000 radios, if you burn out the transmitter just swap them and make the one with the pristine transmitter the new replacement. Or you could always run it at medium power. You might never have a problem with less power running through it. I’ll be really interested in what you decide to do. For my rocket club I have plans to pick up an RT97s. We would use it one day per month for eight months of the year and probably only ten minutes total each of those days. I’ll simply ask my members to say my call sign every so often to ID the repeater. The only reason to have it is to allow people looking in gullies to be able to radio back to base.

Honestly I wouldn’t even worry about the duty cycle. I’m sure in some places repeaters get a lot of use, but most of the ones I hear in Montana are seldom transmitting more than twenty minutes continuously. Run it until it needs to be replaced, then you’ll have a pretty good idea.

You’ve got it! Best wishes getting that set up!

I didn't vote. I'm not one to put stickers on my vehicles, though and I really don't drive around with my radio on. I only use my GMRS radio when my kids are at our cabin or when I'm launching rockets with friends. I don't use GMRS the way I use ham radio, where I might sit at the radio an try to listen to distant stations or join in a local net. For me, although I'm interested in the technology and regulations, GMRS is just a way to communicate while enjoying other things.

It can be as simple as instructing anyone who uses your repeater to identify it whenever they identify their own stations, but of course that's subject to human frailty. For example, if I were using your repeater, I would say "This is WROM258 on repeater WRMM689." Some (most) people purchase a device called an ID-o-matic, that sits between the two linked KG-1000G boxes and which automatically follows the rules for station identification. The Retevis RT97 doesn't have an easy way to insert an ID-o-matic. Its newer version, the RT97S has a port that should allow the use of the ID-o-matic, but I haven't done it so I cannot comment on whether it's easy or difficult. The RT97S used to be much more expensive than the RT97, but lately they appear to be very close in price. In fact, the shopping portal associated with this site had the RT97S for $100 off just the other day, but I think it was a limited time offer. Edited to add: And there's at least one repeater owner who simply setup a Baofeng attached to his/her computer which transmits a call sign to the repeater every fifteen minutes: Here are the FCC rules for GMRS identification: § 95.1751 GMRS station identification. Each GMRS station must be identified by transmission of its FCC-assigned call sign at the end of transmissions and at periodic intervals during transmissions except as provided in paragraph (c) of this section. A unit number may be included after the call sign in the identification. (a) The GMRS station call sign must be transmitted: (1) Following a single transmission or a series of transmissions; and, (2) After 15 minutes and at least once every 15 minutes thereafter during a series of transmissions lasting more than 15 minutes. (b) The call sign must be transmitted using voice in the English language or international Morse code telegraphy using an audible tone. (c) Any GMRS repeater station is not required to transmit station identification if: (1) It retransmits only communications from GMRS stations operating under authority of the individual license under which it operates; and, (2) The GMRS stations whose communications are retransmitted are properly identified in accordance with this section.