Bill,
I agree with you and was aware of their limitations/concerns regarding warranty and performance of the amplifier. They are using RG-6 for their mail cable on the inside and outside antenna. However, they are not using the standard cable TV size screw on connectors...they are much smaller! Had they been using a normal size connector, I probably have a half dozen 3' to 8' coax jumpers in the shop and would have quickly added on....but...
I have been a HAM operator for decades and lots of CB stuff before that, so I have done my share of installing my own ends and such. I chose to reroute my cable to give the unit a 100% shot at exceeding my expectation. In the future I can always reroute the cable and add in a short extension.
I have now installed everything and my phone inside the camper is showing 4 bars (which truly means nothing when balanced against the DBM (decibel-milliwatt) scale. The lower the number the stronger the signal. I opened the setting on my phone so I could read the DBM and I was at 101...which is ok. I then turned on the unit and after about a minute my phone (still in the same location and about 8' away from the inside antenna) had dropped to 88! I then moved my phone to about a foot from the antenna and my signal DBM dropped to 73. That said...I was impressed with the difference and it is true what they say about phone to inside antenna distance. If you're dealing with a minimal signal...they you need to use your phone closer to the inside antenna.
Bill, Thanks for your input...always appreciated!
Travis
https://powerfulsignal.com/cell-signal-strength/