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On Nov 6, 10:08*am, spamhog wrote:
Thank you all! @K1TTT Yes, that's the technically idea solution, but I am trying to use common materials that cost perhaps 5x less around here. @'Doc You have a point. I wrote RG-6-"type". There's a ton of various cables types that are sold commercially as "similar" to RG-6. I referred to the sat-tv cable that everybody uses around here, and you find it in every electrical supplies shop. This cable is designed for use at about 2GHz, which is the IF at which signals are sent down from the LNB to the receiver. - solid copper center conductor - foamed PE dielectric - 100% AL first shield, perhaps .1mm foil - probably 60% AL second shield, stranded - insulation 3kV DC test, in practice not a problem (if you don't crush/melt the foam :-) - emphatically NOT rated for power, tested and perfect up to 50W QRP and RX, theoretically could take 1kW if well matched and not overheat (see specs, do the math) but I never tried and ever will, I'd guess will take 100W OK. I should do a high-current DC test perhaps. - pain in the rearend to mate the AL to anything, must be pressure- only, must be silicon grease coated on penalty or corrosion, but after all this is how perhaps 300 million sat-TV systems work at 2GHz. - loss 2dB/100m (m not ft) @ 10MHz, not bad - ...75 ohm, but I either make my own impedances, or not care, or use tuners, and 75 is OK for many applications. @KD7HB Plastic tape is probably the simplest and best, perhaps without even wrapping the whole length - at a 30deg. angle spiral wrap I would need 240ft of tape! :-P. Also, tape is much gentler than sttap in terms of pressure per unit of surface. *Dish installers never use nylon straps outdoors, just several turns of black, weather resistant PVC tape, and it lasts at least 5-10 years. *In my case, the drop is all inside a flue line, well protected. Maybe I should use a large rope just for wider surface. *I'll do an overload test and see. But another post around her tells me that perhaps there's a was to test the line at 2GHz... Thanks again to all. rg6 or 11 with steel messenger may be common depending on the local cable tv practices. it is often used for running drops from the pole to the house by catv installers. rope would work in place of the cable, but pick a non-stretchy one. polypropylene would be my first choice since it will be out of the weather. and yes, only a couple turns of tape every 3 or 4 feet should be plenty. and since it is enclosed you may not even need to go all the way down, just enough to get to where you aren't afraid of the weight of what is left stretching it any more. |
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