I have an AA54. It provides TDR graphing of your coax and can identify damage areas by distance and Z.
With a multimeter, short the far end and measure d c resistance. and compare to the specs. Not a bad idea when installing new coax is measure its resistance and Zo and keep in a card file for future comparisons. -----------------------------------------From: topband-requ...@contesting.com To: topband@contesting.com Cc: Sent: Saturday October 17 2020 12:00:42PM Subject: Topband Digest, Vol 214, Issue 17 Send Topband mailing list submissions to topband@contesting.com To subscribe or unsubscribe via the World Wide Web, visit 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. > > 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. > Reflector > ------------------------------ Message: 4 Date: Fri, 16 Oct 2020 18:40:49 -0600 From: Don Moman VE6JY To: topband Subject: Re: Topband: Checking the integrity of 75 ohm cable Message-ID: Content-Type: text/plain; charset="UTF-8" Try to find/borrow a older Tek 1502 TDR, they are inexpensive on ebay (~$100) and show way more detail than any of the analyzers I've tried. 73 Don VE6JY On Fri, Oct 16, 2020 at 5:50 PM Michael Walker wrote: > 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 > 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. > > > > ------------------------------ End of Topband Digest, Vol 214, Issue 17 **************************************** Links: ------ [1] https://www.fcc.gov/media/radio/am-query https://www.fcc.gov/media/radio/am-query /> > > 73, Jim K9YC > _________________ > Searchable Archives: </br<></a><a href= [2] https://www.fcc.gov/media/radio/am-query https://www.fcc.gov/media/radio/am-query /> > > > > 73, Jim K9YC > > _________________ > > Searchable Archives: </br<></a><a href= [3] http://www.contesting.com/_topband _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector