RigExpert has a variety of Antenna Analyzers that have a built in TDRs. I highly recommend them.
Mike va3mw On Fri, Oct 16, 2020 at 5:15 PM Jim Brown <[email protected]> wrote: > On 10/16/2020 1:26 PM, Gary Smith wrote: > > What would be an easy way to tell if these > > coax have been damaged in some way? > > > > I do have an old MFJ-259B > > That might give you a clue if the cable is open or shorted, but it's > unlikely to show chewing that doesn't cause an open or short, but allows > water intrusion, etc. > > The best tool is a vector analyzer that includes software/firmware with > a very good TDR function. I use the VNWA3EC, built by hams in the UK > from a design by DG8SAQ, who also does both firmware and software. > > https://www.sdr-kits.net/DG8SAQ-VNWA-models > > The TDR function in this unit is really excellent, and can be used with > the antenna connected. The procedure is to do a very wide sweep (I > usually sweep 50 - 500 MHz) so that fine detail shows up clearly. > Software then does an inverse FFT on the sweep to get the TDR, and > allows the user to choose which of five different windowing functions > provide the clearest view of the measurement. > > There are ultra-cheap VNAs around, but I don't know the capabilities of > their operating software. > > One way I test my RX antennas is to use them to listen on the AM BC band > while I switch directions, using this FCC website to tell me who is > where on each frequency. > https://www.fcc.gov/media/radio/am-query > > 73, Jim K9YC > _________________ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
