tweiss3

Problem with P25, is you can only get very narrow equivalency if you go trunking (Phase II), where as DMR does it 100% of the time, and NXDN can run two separate repeaters side by side in the same bandwidth as a single P25 or DMR repeater.

Any further progress on this? I'm interested to hear if you do end up getting it to work as more than a 2 channel radio.

I agree, it will be one of the big 3 (DMR, NXDN or P25). If you get to listen to the big three setup correctly side by side, there isn't much of a difference. DMR being flooded with bad IP links, barely operational hotspots, and cheap radios does affect how it sounds. Local via repeater, on Motorola/Kenwood equipment only, you can't really tell the difference between the 3. P25 phase 2 does sound different, but that would never show up in GMRS, because that's a trunking only protocol.

I had to pull the sticker off from around the contacts on one, and used a cloth and rubbing alcohol to make it work. One of the contacts was pretty green.

Why compromise and select 1. Sure, getting everything costs more, but in my experience, its worth it. You also forgot selectivity/sensitivity, which is hugely important. Don't forgot availability of support locally. That's not even starting a discussion about uses beyond GMRS, which may or may not be important to others.

What does the radio do when you go to channel 3?

I'm interested in this project. This seems the same process as getting on 902MHz for ham. I would bet GMRS wouldn't be a problem, firmware probably isn't smart enough to block that out completely. Getting down to 440MHz might prove difficult. I do wonder where the hard stop is at the bottom.

Did you download the specific driver from bluemax49er? Also, you may need to change the com port number, usually between 0 and 3, and select the appropriate port number in the CE27.

look up the FCC ID, it will show what the frequency range for that ID/transmitter is.

What radio were you using? I haven't made it successfully, but my understanding is that even with Doppler, the frequency does change throughout the contact. I doubt you had too much gain, as those I know that make those contacts do so with Yagi/Beam antennas with gain over 11dbi. I would guess you were slightly off frequency on the receive, but on the marker on transmit. I know my IC9700 has an auto tracker than can track the received carrier and adjust as it moves with the Doppler shift, but I don't think any other radio has that. Others use the computer to adjust on the fly.

I found it. It only "doubles" the range in 1 direction, and they use 20' of separation which gives 47dB of isolation. It is not bi-directional, so it is kind of a pain in the rear, and won't help most situation, but what do you expect from license-free solutions.

I think any implementation would have to come from Motorola directly, or whichever FHSS radio manufacture you are using. That being said, lets talk about a theory that might work as a repeater. My understanding is the radios utilize at least 50 frequencies, and hop about 50 times a second. The privacy is caused by changing up the hop set (order and number of frequencies), which means any repeater would have to be programed identically to the radios, but that's not a problem, that's typical of repeaters. Two problems exist, which we have to overcome: 1) At any given time (snapshot), the radios are using a single frequency for both receive and transmit. This could potentially be overcome by having a small delay in the re-transmission, say 2 hops behind the transmitting radio. Any radio in range of the transmitting station would continue to sync and receive from that station, stations outside that range would instead be synchronized and receive from the "repeater" station. Problem solved? 2) Second problem is, a traditional repeater usually has a fixed frequency set, and uses a duplexer to separate receive from transmit to eliminate desense in the receiver. The alternative is two antennas. Since 902MHz is such a high frequency, vertical separation can be relatively small and provide good isolation. 1 foot vertical provides 27dB isolation, and 2 feet increases that to 39dB, more than enough decent selectivity can overcome. Make sense? I think the theory would work, practice might be a bit harder to accomplish. There there is getting 15C certification for the "repeater".

I just tried to read through the rules (15C), and I don't see this being permitted. They even went as far as limiting the power, antennas and the gain on any antenna in an attempt to limit range. Also, I don't see how this would even work, its not operating on a frequency split, so it would have to be a store and forward type repeater, which might make the receiving stations hear the transmitted message twice.

I have 1.2, the base has D-Star, the HT does not. 900 is less expensive to get into.

Considering how empty the 902 ham band is, run P25 and nobody will hear you anyways.

The FAA has a notice criteria tool: https://oeaaa.faa.gov/oeaaa/external/gisTools/gisAction.jsp?action=showNoNoticeRequiredToolForm I have had to file notice for buildings and even substation power lines before. I have also used that tool to prove buildings are not tall enough to extend into FAA airspace.

My understanding is they want to see the testing to include more points directly in the GMRS range, which typically is not included in the wide range part 90 testing. The secondary part is they probably don't want to deal with the whining and support to the typical licensee with the programming software. The usual cast of characters that whine when they have to downlead the free software/driver from the web to use the cable provided in the box and program their radio couldn't fathom paying a few real bucks for the correct cable and software.

The only reason main stream manufacturers abandoned it is the changes to get part 95 approval. When a radio gets Part 90 approval for 403-512MHz, they used to be able to fill out one form, and use the existing test to get Part 95 approval. Now, they are requiring a entire second test and full set of submission to the FCC. For the percentage of the market that GMRS is, they all said no thanks and walked. Heck, similar can be said for Part 80 (marine), but manufacturers will apply for that one because the market is much bigger than GMRS. There are many commercial radio needs for Marine service radios with IS ratings (XPR7550e comes to mind). EDIT: For what it's worth, if it gets tested and approved in Part 90 for a block of frequencies that include the GMRS set, I see no reason it shouldn't be allow to get Part 95 on the same test. Granted, it may be stuck at narrowband, but that's still better than having to run another test.

When you are up at 1500 AGL, often times the entire repeater is cabinet mounted that high on the tower, with a very short coax run.

QRP phone is fun as well, while it's a bit difficult, the challenge can be rewarding. I did upgrade to the 705 for my QRP station, because the package is pretty dang complete. Having a waterfall can be a huge benefit when searching out contacts.

Check the pins, and rub all the dirt off the contacts on the radio side.cn

True, but if you turn it down to 1W, and use physical separation of the two RF decks, good commercial equipment should have enough selectivity to have no issues when the VX1000 is on 1-8 and the radio is on 15-22.

Another option, the Vertex VXR-1000 "in car repeater" has Part 95 approval, and you could connect it to the back of your commercial radio's DB9/25 connector and have HT access to your base station throughout the house.

AGREED! A TK-890with dual heads sounds like a good option

Why don't you look for a radio that has a dual control head option.