tweiss3

Ok, so not all encryption is compatible between manufacturers. I'll give a common example. Both Kenwood and Motorola had DMR radios, but their "basic" privacy is not compatible between the two. Motorola's is a 16bit XOR, Kenwood's is a bit different, thus incompatible. The "basic" privacy is typically a non-standardized encryption that is for basic privacy at little/no cost. Now, you can use Enhanced Privacy/Enhanced Encryption in Moto/Kenwood DMR, because they use a standard, ARC4/RC4 40bit encryption. Same goes for other standard methods of encryption such as DES (64bit) and AES256 (256bit) which is compatible between manufacturers, as secure interoperability is required. These methods of encryption can be used with NXDN and P25, based on options available (both cost and free) for each radio. Loading encryption, when meeting opsec/FIPS requirements, creates the key, which is stored in either a hardware or software vault, and then loaded into the radio via manufacturer specific software, or with a hardware device called a keyloader. The keys can be transferred between secure devices (keyloaders/vaults) but after creating and storing them, you can never view what the key is again, so store it properly. In the case of many of these Chinese radios, security and standards are typically not followed. You basically copy the key into the software, apply it to the digital channel desired and that's it. Keep in mind, since they don't follow the standards, the encryption may not be compatible with others. The AES could be AES128, or just a completely made up 256 encryption method applied to DMR different than the standard, thus not compatible with other radios using industry standards. @WRYZ926SINCGARS uses frequency hopping for security, which not only doesn't show up on a scanner/close call, it's impossible to follow without the starting frequency and hop-set, which is why it's just as secure as AES, if not more.

Interesting results, pretty maxed out for a "mobile" duplexer. As for your coverage, I have to wonder if your antenna is mismatched for priority coverage. It's not uncommon to go for higher gain, then shooting your RF pattern over your intended close coverage. This isn't an uncommon problem. No doubts that neighbor's household items and the vegetation can be part of the issue, but unless its all pine, I have my doubts that it is the next biggest issue you have to correct/improve.

I have a handful of them for various uses/projects. Other than being rated for 5W, they do great, just spend some time and align it correctly, they can get sensitivity down to about -120db or better. The FCC approval occurred before Part 95E approvals were a thing, previously they just called it Part 95, so yes, its approved. Now, your amplifier won't be approved.

I would also be weary of adjusting the power using the input voltage. That sounds dangerous for the long term survival of the circuits. That typically isn't the correct way to adjust a transmitter.

If you look at the table, it's performance narrows and insertion loss increases as you approach 5MHz spacing. There is no way in hell that will have acceptable performance at 3MHz spacing.

Be careful, that specification indicates a minimum spacing of 8-10MHz between RX and TX, but the US standard for UHF is 5MHz.

Or hoarded by Crown Castle or another monopoly.

I agree, but I don't see another way to remain within GMRS, unless you use two antennas and mount them like a dipole and only use 1/2W. I have a trunked P25 P1 "site" in my living room where the CC is 0.05MHz below the VC, RX antennas are pointed up, and TX antennas are left and right away from each other. Works well, but it's only putting out 0.1W. In theory, its a $7+M idea that would likely just become space junk before it is used.

While correct, I suspect the crowd-funding would be significantly short of the cost to get one up in near earth orbit. I wonder what space dust and the extreme temperatures would do to a "mobile" duplexer though.

It is just a out the nicest day here.

As others have said, ham UHF vs GMRS, you won't notice a difference with HTs. VHF high (2m) will get a bit further under normal conditions. VHF low (6m, 50MHz) gets to the point that an adequate antenna is the issue for HTs. It will act the same as 2m without atmospheric propagation helping, but when propagation is open, there are thousands of stories of talking across the USA on only 5w.

I need to get back to studying for AE. Same as last years study course, life got busy and I'm behind again.

Heh. My wife doesn't necessarily participate, but finds them useful at times. She didn't really say anything after she saw my last purchase order other than "that's a lot of money" then walked away and didn't mention it again.

You want hardline, like Heliax (Comscope/Andrews) or whatever RFS calls it. At 50', you are looking for 1/2" or 7/8", unless you can find a deal for larger somewhere.

As mentioned, testing of an HT antenna is nearly impossible to get completely accurate results. It should also be noted that sometimes a "better" antenna will cause the radio to perform worse due to RF saturation. That being said, for the APX, the Motorola antenna will work the best for that radio.