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## Re: [TowerTalk] Measuring Coax Loss

 To: garyschafer@comcast.net, "Tower and HF antenna construction topics." Re: [TowerTalk] Measuring Coax Loss "Richard (Rick) Karlquist" "Tower and HF antenna construction topics." Thu, 11 Feb 2010 20:59:07 -0800 mailto:towertalk@contesting.com>
 ``` Gary Schafer wrote: > Hi Rick, > > I don't think that I have used the method that you describe. What happens > when the cable length approaches a quarter wave length? Or is this only > valid at a small fraction of a wave length? > > 73 > Gary K4FMX This is intended for low frequencies where the coax is much less than a quarter wave. If you can measure a quarter wave of coax, then the thing to do is measure the Q of it as a resonator, from which the loss follows. The Q can be measured very accurately by various techniques. Which one is best depends on various factors. Hard to give a one size fits all answer. I recently measured the loss of 10 feet of 7/8" hardline that I got free by measuring the Q of the 1/4 wave resonance with my HP 4815 vector impedance meter. Measured the frequency difference between -45 degrees and +45 degrees and divide into the center frequency. This measurement also gives the velocity factor. I needed that so I could determine how long my 3000 foot piece was without unrolling it, hi! Rick N6RK _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```
 Current Thread Re: [TowerTalk] Measuring Coax Loss, (continued) Re: [TowerTalk] Measuring Coax Loss, Jim Brown Re: [TowerTalk] Measuring Coax Loss, Mike Besemer \(WM4B\) Re: [TowerTalk] Measuring Coax Loss, Stan Stockton Re: [TowerTalk] Measuring Coax Loss, Mike Besemer \(WM4B\) Re: [TowerTalk] Measuring Coax Loss, Dan Schaaf Re: [TowerTalk] Measuring Coax Loss, Mike Besemer \(WM4B\) Re: [TowerTalk] Measuring Coax Loss, Mike Re: [TowerTalk] Measuring Coax Loss, jimlux Re: [TowerTalk] Measuring Coax Loss, Rick Karlquist Re: [TowerTalk] Measuring Coax Loss, Gary Schafer Re: [TowerTalk] Measuring Coax Loss, Richard (Rick) Karlquist <= Re: [TowerTalk] Measuring Coax Loss, Richard (Rick) Karlquist Re: [TowerTalk] Measuring Coax Loss, jimlux Re: [TowerTalk] Measuring Coax Loss, jimlux Re: [TowerTalk] Measuring Coax Loss, Cqtestk4xs Re: [TowerTalk] Measuring Coax Loss, Mike Besemer \(WM4B\) Re: [TowerTalk] Measuring Coax Loss, Dan Schaaf Re: [TowerTalk] Measuring Coax Loss, Mike Besemer \(WM4B\) Re: [TowerTalk] Measuring Coax Loss, Roger (K8RI) Re: [TowerTalk] Measuring Coax Loss, Cqtestk4xs Re: [TowerTalk] Measuring Coax Loss, Rick Karlquist