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Excellent explantion of why a higher end radio will recieve a good signal 20 miles away when a CCR only gets it 16 miles away. Too bad everyone inside the 15 mile circle will never know the difference.

Have you checked the SWR past the duplexer (checking the feedline and antenna?) Also check your jumpers, its possible you accidentally hooked swapped them and is often the problem. RG8x isn't very good for short repeater runs let alone the length you are running, While I doubt thats causing your swr issue, it will greatly reduce the range of the repeater, especially at longer lengths. Personally I used LMR400 then upgraded to 600 which in my opinion is fine for running 30-40 feet up, though there are guys here who will demand 1/2" or 3/4" helix which for the type of install and the cost, I just dont feel its worth it. If the SWR is good past the duplexer, then it would be reasonable to believe the duplexer is bad. Most flatpacks that I have seen are only rated to 45W for UHF band, and work best at wattages below 25W. `If you are putting 52W in you may have caused some damage to the internals, and could have damaged the repeater itself. So, I would try running low power, around 20W or so, and see if that gives you better SWR readings. Last, I would recommend changing out the flatpack for a band pass/reject style duplexer. The difference will shock you for two reasons. #1, the Chinese flatpacks arn't made with the best quality and often have issues with them and are never tuned correctly. and 2) BP/BR duplexers seem to just work better than the flatpacks do.

Your duplexer is mis-tuned! It should be tuned to precisely the frequencies you are going to be using. The entire purpose of the duplexer is to allow only a single frequency to pass with minimum loss, while supressing any other frequencies. The easiest way to explain this is with a picture. This image is from a VHF duplexer, but the principles are the same. Note that the green line represents the lower frequency of your pair and the red line represents the higher frequency. It is important to note that any frequency lower or higher than the tuned frequency is quickly attenuated. This is precisely why you are losing so much power when you transmit:

You need to look at EVERYTHING! And even then you may still get burned. You can get some very good equipment and deals on eBay but it takes time and research what you are buying FIRST before spending your money. I was looking at what was advertised as a TK-3170 UHF radio. Some of the photos looked like they were lifted from the manufactures web site, had that "new" look, not what you expect from a "used" radio. Others showed obvious signs of usage. One showed a partial of the rear of the radio which showed the model as a TK-2170 VHF type, which I would not mind getting anyway, so I ordered it. Well it showed up and it was a TK-3170 alright, name plate didn't match the sellers photo, but for the totally useless band spread of 400 MHz to 430 MHz. It was now obvious the seller was completely dishonest in his listing and knew it, not a common mistake where some sellers get the model or description wrong. That's why I like seeing the name plate with serial number, FCC ID and model number. The seller had a 99.8% rating too, but not after I was done with the feedback. I finally got eBay to refund the cost plus shipping. I've purchased plenty of handheld radios off eBay, have a good collection of them, so I know what to look for but still got burned. So if you don't have experience buying used, don't, or have somebody who does look it over and do your research.

Thank you! lol... yeah, of course nobody would buy an airsoft barrel... ahhaha... sorry if I wasn't more clear...

I think his point was that there's both good used stuff and garbage on eBay, and it takes some dilligence to choose the good stuff.

Thanks for the information and now it makes sense. I apologize for a asking, but sure to appreciate you taking the time to explain.

I just realized I never posted the final configuration of my base station antenna. I ended up building a tilt-over mast with a simple 1/4-wave ground plain up at 27ft AGL fed with about 55ft of DRF-400 coax running to the radio. I have tested the base to HT range with my Midland GXT 1050's and can get at least 5 miles to the HT if I am not in a low spot. I have also been able to hit a repeater over 50 miles away that was LOS. I also am able to hit my local repeaters in my local Front Range GMRS group. So basically I did my research online, took excellent advice from this group, did my calculations and that, with a little bit of luck, managed to exceeded my original requirements. EDIT: Added a photo I neglected to the other day. John ];')