Leaderboard

In the old days, almost all transmitters had pi-network outputs, and would transmit into anything without going into fold-back or shut down. We would simply tune cavities by transmitting through them into a load. For a set of pass cavities, transmit on the desired frequency, and tune the cans for maximum power throughput. For reject cavities, transmit on the unwanted frequency, and tune for greatest null. You can't really do that with modern transmitters, as they will just shut down.

For less than 50' RG8X is ok (I've used it for ham radio for years without an issue) anything over 50' and I seem to get signal issues. As for your antenna, you may wish to look for something like this: https://www.amazon.com/Browning-450MHz-470MHz-Mobile-Fiberglass-Antenna/dp/B00IDTJ3AS/ref=sr_1_5?keywords=GMRS+base+antenna&qid=1561855637&s=gateway&sr=8-5 The antenna is about 2 feet tall and does not require a ground plane to operate. When I had mine I had no SWR issues, (Typically 1.0-1.1:1) I mounted it on the vent pipe for the sewer with a short 1.5" pole and some straps. There is two reasons why I would stay out of the gutter. A) the magnetic bases arn't small, even a 3" gutter may have a hard time fitting the smaller of reliable antenna bases in it. This leads to clogging of the gutter which can back up into the fascia causing mold and rot issues. Add to it that most mag mounts are merely water resistant and not completely waterproof and you have the makings for a disaster for your radio and house. B ) The gutter isn't wide enough to give you an effective ground plane which is needed for mag mount antennas. Normally, you want your ground plane to be opposite the radiating element (Like a di-pole) or spread evenly around the element. Using the gutter, you would have two directions with good ground plane and the rest where ground plane is non existent. This affects the signal pattern of the radiating element during TX and can throw SWR off. It also can cause issues with RX as the ground plane tends to reflect signals into the element (much like a satellite dish.) Don't get me wrong, it could work and is a better solution to running a 5 watt portable from inside of the house, but if your looking for longer distances your best bet is to go with a true base antenna.