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As SWR is a constant topic in radio, and since it may be difficult initially to grasp the concept of, I thought it would be helpful to provide a link to an incredibly effective video that allows you see it in action. The video is 60 years old and was produced by AT&T labs. It is worth watching from start to finish. You will get to see standing waves, reflected waves, impedance matches, mismatches, shorts and opens. It does not get visually any clearer than this. Enjoy. Michael WRHS965 KE8PLM

Ed warrants his antennas, so perhaps it is worth a call to him. Before you do, check it one more time outdoors away from the building. Michael WRHS965 KE8PLM

The reason antenna (and therefor radio outputs) were designed to be 50 ohms is largely the coax. 50 Ohm coax is practical to make in manageable diameters and will carry decent amounts of power. They determined that 50 ohm coax for a given size could carry more power than other impedances. It was deemed optimum by some military research study. Also, with low voltage solid state radios it works out very well. Once you choose 50 ohm coax for your radio system it makes sense to have the radio and antenna made to match it. Of course there is 300 and 400 ohm twin lead transmission line (ladder line) and some radios used to be designed for it. It made far more sense in the tube days to design higher Z finals on radios. But that's mostly history - at least for our portable 12v radios. Most radio outputs are predominantly resistive impedance with little reactance (inductance or capacitance). Vince

There are only eight high-power channels, seven 5W channels and seven 0.5W channels. Any half-decent radio can scan them all quickly. And from your mobile you can't legally use 467.xxx5 (because 0.5W), so why to worry about them. If there is an open repeater in vicinity, it's most likely will be on 462.675 with tone 141.3.

I would advocate that you conduct simplex testing first to confirm you can communicate between your intended sites before investing in repeater specific gear. The results of those tests will be incredibly beneficial. If you achieve exceptional results doing simplex, then there is reasonable chance of success with a repeater. I have considered hosting a repeater on my property, but have not yet chosen to do so. Even though my elevation is good (at or above everyone else for miles) I know from testing I would still need to get my antenna well above the trees (perhaps 100-120 feet or more AGL) to achieve reliable repeater coverage out to 8-9 miles and be suitable for reliable use with an HT. My range limitation is mostly foliage density (i.e. the trees are my enemy). The cost of the tower to achieve that elevation detracts me from moving forward. If you are considering the Retevis repeater, it is only 5 watts, so your simplex testing would need to yield exceptional results using only 5 watts of power. I say exceptional, because the Retivis will not work as well as a simplex radio solution. For my testing, I opted for a HD fiber glass pushup mast and high-gain collinear antenna on top. It was suitable for testing, and has found itself now semi-permanently installed next to the house. Here is an image taken when i was doing my simplex testing. Top of antenna in this picture is 56’ AGL. Bottom line, if you can’t simplex between the intended sites from your desired antenna elevations, using the intended amount of power, there is zero chance of repeater success. So, my advise is to keep your expectations realistic, do your testing first so that when you do decide to invest in a repeater your expectation bubble will not burst. Michael WRHS965 KE8PLM

Start? They already have been ?