oddly enough, I found some 'Direct TV High Definition' RG-6 that has a solid coppercenter conductor. it seems to behave better at low frequ's than the copper cladsteel. less loss and closer to 75 ohms Zo. ( i get 79 ohms on 160m with my VNA )
Zo seems to rise as you down in freq. less so with the solid copper center cond. FWIW, 73, W5XZ, dan --- On Tue, 2/1/11, Jim Brown <[email protected]> wrote: From: Jim Brown <[email protected]> Subject: Re: Topband: Skin Effect of RG-6U To: [email protected] Date: Tuesday, February 1, 2011, 12:31 PM On 1/31/2011 3:02 PM, Dennis W0JX wrote: > I have found that the quality, and therefore the loss, of RG-6 cable varies > quite a bit. On the average, I measure about 14 ohms of resistance in 500 > feet if shorted at the far end. Recently, I put up a dual flag RX antenna and > felt that the sensitivity was far down from normal. It turned out that my > resistance was about 20 ohms for 500 feet. I discovered some oxidized > connections in a splice and also some water contaminated aluminum shielding. > If you are going to use long runs of RG-6, I recommend Quad with the larger > center conductor, very careful sealing of any splices to prevent moisture, > and if available, flooded cable to seal any pinholes. Great advice. Also, stick to major mfrs like Belden and Commscope. > > I have found that the low-price Home Depot stuff has a PVC jacket which is > easily cut and exposes the braid to moisture. The aluminum shield then starts > oxidizing. See http://audiosystemsgroup.com/Coax-Stubs.pdf 73, Jim K9YC _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
