inside radio meters can be ballparked to give a ballpark reading (not perfect but something to go on) Most SWR bridges and or run of the mill type meters (Radio Shack) will basically give a slighty better SWR reading ,again not perfect but at least something to go on . Most of those type meters will need at least a 3 to 4 watt DK into them for them to work correctly , (quoting Linearone) to low a DK (like 1 or 2 watts which many amps are tuned for) will not work these meters correctly enough for the ballpark readings. IM far from a perfectionist in this Hobby and Radio Shack type meters have worked very well for me over the years , again I say ,it's not perfect , but more so good enough then not. if you want to spend some money there are plenty of other "better" meters out there on the market..and when I mean spend ............300.00 or so for a Antenna analizer ain't cheap , but there are lessers models for lesser dollars. I suppose I'd have to be really into antenna's and or installs (or hit the lotto) for me to ever invest that kind of money for one of those antenna analizers. Those things surely have a way of making guys who use other matching devises look bad.........but no matter how technical we can get ........Ballpark works.