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First trail GMRS use and man, do I prefer that over CB. Still have the CB installed in the Jeep as it will be a secondary form of comms for others that haven't seen the light yet. Running trails in Moab. Ran Elephant hill yesterday and on the way out, the team leader was well over 5 miles out and some generous but not too heavy terrain between us and we were talking back an forth as if we were standing next to each other. Oh yeah!

I got my extra class ham license in 1985 and live out here in Spokane. I often monitor the ham repeater system here that covers essentially the whole eastern half of Washington state. I also belong to the Spokane VHF Club. I find that most of the hams are surprisingly receptive to GMRS and many (or most) of them have their GMRS license. They talk about GMRS on the ham repeater now and then. They also have discussed it on the VHF club net and at meetings. The reason is that most hams have family members and fishing buddies who are not hams. So ham is pretty useless for communicating at camps and family outings. Most hams love all kinds of radios. Also, hams believe that GMRS brings people into ham radio. So they don't see it as competition. They see it as something that promotes amateur radio. Of course there will always be some delicate egos out there. A few guys see ham radio as a religion. They worked very hard to get a license and don't like people who just "wrote a check". I almost like GMRS better than ham sometimes because it is less exclusive. Ham is sometimes just too quiet. Vince

You are absolutely correct. Were this portable repeater going to be in continuous use its current parameters would be an issue. However, its intended usage is to be deployed anywhere within our ARES five counties for emergency coverage likely no more than two or three days, it shouldn't be much of a concern. Our plan is to use a unity gain antenna no higher than 20' to reduce any chance of interference with other 70cm operators. I just got it two days ago and haven't had time to bench test yet. I may in fact wind up tightening up the notches on the duplexer if it proves to be a problem. There's a lot of testing yet to be done! EDIT: I have determined that the interference from the Attica repeater was a result of tropospheric ducting. I've not heard the digital 'noise' since around 1500 CST yesterday afternoon.

I would be interested in knowing how deep the notches are for the duplexer. The typical cheap Chinese ones they use are spec'd for around 70db and that's at a very narrow bandwidth. To get a 500KHz bandwidth I suspect the notch depth is rather poor, traded off notch depth for bandwidth, leading to poor performance, i.e poor off frequency rejection and RX desense from the TX side. My understanding is the TX side of the notch filter should be tuned for the exact RX frequency for maximum notch depth while the RX side of the filter should be tuned for maximum notch depth at the TX frequency.

Phantom antennas suck. Do a simple test: Put on the Phantom antenna, run your VSWR test, then step back 10 ft. from the vehicle & tilt your head 10 degrees to the right. Now, screw on a standard 6 inch hatpin UHF quarter wave antenna, measure VSWR again, and then step back 10 ft. and tilt your head 10 degrees again, this time to the left. I'm thinking the 1/4 wave hatpin will look much better after running your test. The 10 degree head tilt is optional.

So, this is really embarrassing. . . It is the label on the side of the radio. JG

Here is a snap shot of my NanoVNA showing the resonance of the external GMRS at my home. The resonance can recognized by the sharp dip in the yellow LogMag trace. Since the impedance of the antenna (as depicted in the green smith chart) is also closely matched to the 50-ohm coax there is also a corresponding dip in the SWR. So this image shows that, in my case, the best SWR reading corresponds with the resonance of antenna. So, in part, how can you view the resonance of an antenna independent of SWR? Use a NanoVNA, perform an S11 measurement with the instrument set to display the LogMag trace. Hope this helps. . Michael WRHS965 KE8PLM

Actually a nice nanoVNA would certainly work as well. It's a bit more of a learning curve simply because it doesn't have the pre-written macros like a RigExpert has. If you go that way, spend the few dollars more to buy one with the largest screen you can find, as the smaller versions have such a tiny font they are very difficult to read... Truthfully, a nanoVNA can do a lot more than the RigExpert does, certainly more than the MFJ analyzers can do. There's a reason why MFJ is semi-jokingly called "Mighty Fine Junk..."

One more votes for his books...that was one of my sources when I tested for tech, and I'm planning to pick up the one for general as well.