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#1
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On Feb 1, 8:58*am, RHF wrote:
On Jan 31, 11:55*am, bpnjensen wrote: Well, put up a new inverted-L antenna - 30 feet up a tree, 60 feet across horz and over the house rooftop (nowhere else to go!), base ~20 feet from house. *Using a winradio 9:1 unun matcher at the base, *not yet grounded*. *In fact, so far none of the RF chain on this antenna is grounded. *So far, so good - noise level *fairly* low (lower on almots all freqs than my DX-Ultra), AND signal strength on most bands roughly the same, varying depending on the band. *One good thing I do notice is that on strong MW stations, he antenna does *NOT* reveal a 60 Hz background hum like the DX-Ultra does - I consider this a good sign. *The far end is about 25 feet from the higher-tension power lines out back, and the near end is about 15 feet from the low-tension lines in front. *Next steps - - 1 - Ground the 9:1 unun - 2 - Bury the coax from house to base of antenna - (about 18 feet underground) You can use 1/2" Polyethylene Tubing to Buryhttp://www.dripdepot.com/1045 your Coax in if you don't want to use PVC Pipe. *. Seal the Tubing ends with one of these.http://www.touch-n-foam.com/products.php *. - 3 - Install RF isolator (Either Radioworks or - Wellbrook AFI5030) at the house with or - without a ground stake connection, Usually you should try and get this Ground Rod were the Coax is coming out of the Ground; and as close as you can get it to were the Coax is about to enter the House. *. - depending on what works the best. - - Have not had great reception so far this week, - so no chance to really give it a workout. Then things can only get better. - Further reports to come. -*Thanks, guys, for all the input so far! Post It When You Hear Them ) ~ RHF*. *. Good idea on the tubing. Since I already have the PL-259s on the cable, I may go for 3/4" or 7/8" ID tubing (they should snug through that size tube, IIRC). I already have the 8' ground stake in at the edge of the foundation, so it's practically plug and play if I ground that RF isolator. I was thinking of using CoaxSeal for the tube ends, since I have a mess of it. Question - does the additional Poly tube around the coax diminish the capacity to provide (presumably useful) inductive ground for the buried cable? If the coax is not "entubed", does the covering break down in soil? I have RG8X for the run...PVC coating IIRC. Bruce |
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#2
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On 11-02-01 11:22 AM, bpnjensen wrote:
Question - does the additional Poly tube around the coax diminish the capacity to provide (presumably useful) inductive ground for the buried cable? Seems to me that anything resembling an inductive ground would be a bad thing. The inductive coupling effect would vary completely with the frequency of the signal, proximity, length, etc. Not good. Don't settle for anything less than a real, lowest possible impedance, honest to G_d, mechanically connected ground. I usually smear the wire connection and electrode with vaseline after having sandpapered them. Then do your clamping. A plastic cup inverted over the end of the ground rod will keep the rain out of the joint. mike |
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#3
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On 2/1/11 12:41 , m II wrote:
On 11-02-01 11:22 AM, bpnjensen wrote: Question - does the additional Poly tube around the coax diminish the capacity to provide (presumably useful) inductive ground for the buried cable? Seems to me that anything resembling an inductive ground would be a bad thing. The inductive coupling effect would vary completely with the frequency of the signal, proximity, length, etc. Not good. Don't settle for anything less than a real, lowest possible impedance, honest to G_d, mechanically connected ground. I usually smear the wire connection and electrode with vaseline after having sandpapered them. Then do your clamping. A plastic cup inverted over the end of the ground rod will keep the rain out of the joint. mike Or you can wrap it with CoaxSeal. Teflon tape works very well, for this, too. |
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#4
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On Feb 1, 10:41*am, m II wrote:
On 11-02-01 11:22 AM, bpnjensen wrote: Question - does the additional Poly tube around the coax diminish the capacity to provide (presumably useful) inductive ground for the buried cable? Seems to me that anything resembling an inductive ground would be a bad thing. The inductive coupling effect would vary completely with the frequency of the signal, proximity, length, etc. Not good. Don't settle for anything less than a real, lowest possible impedance, honest to G_d, mechanically connected ground. I usually smear the wire connection and electrode with vaseline after having sandpapered them. Then do your clamping. A plastic cup inverted over the end of the ground rod will keep the rain out of the joint. mike Well, that's not quite what I meant - I am sorry if I was unclear. IIRC, there is nothing at all wrong with burying a cable, and in fact it helps to keep the RFI away from the run, as well as keeping the outer braid near the earthen ground and helping to bleed away currents travelling along the braid. That is what I was asking about - whether a poly tube would lessen this desirable effect. I have every intention of grounding the 9:1 unun, presuming it will enhance performance (if it does not, I'll disconnect it). If necessary, I'll also install the RF Isolator and try it both grounded and ungrounded. I had never heard that it was necessary to keep a solid mechanical ground water-free, although I guess I can see the value. I don't understand what vaseline does - just protect against corrosion? I doubt if it would help the electrical connection. |
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#5
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On 02/01/2011 12:38 PM, bpnjensen wrote:
Well, that's not quite what I meant - I am sorry if I was unclear. IIRC, there is nothing at all wrong with burying a cable, and in fact it helps to keep the RFI away from the run, as well as keeping the outer braid near the earthen ground and helping to bleed away currents travelling along the braid. That is what I was asking about - whether a poly tube would lessen this desirable effect. I have every intention of grounding the 9:1 unun, presuming it will enhance performance (if it does not, I'll disconnect it). If necessary, I'll also install the RF Isolator and try it both grounded and ungrounded. I had never heard that it was necessary to keep a solid mechanical ground water-free, although I guess I can see the value. I don't understand what vaseline does - just protect against corrosion? I doubt if it would help the electrical connection. You're not supposed to use braid for grounds. |
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#6
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On Feb 1, 10:41*am, m II wrote:
On 11-02-01 11:22 AM, bpnjensen wrote: Question - does the additional Poly tube around the coax diminish the capacity to provide (presumably useful) inductive ground for the buried cable? Seems to me that anything resembling an inductive ground would be a bad thing. The inductive coupling effect would vary completely with the frequency of the signal, proximity, length, etc. Not good. - Don't settle for anything less than a real, - lowest possible impedance, honest to G_d, - mechanically connected ground. - I usually smear the wire connection and - electrode with vaseline after having sandpapered them. - Then do your clamping. - A plastic cup inverted over the end of the - ground rod will keep the rain out of the joint. - - mike Conductive Grease "NO-OX-ID" http://www.sanchem.com/aSpecialE.htm...FRiAgwodThlG2g CRC® Dielectric Grease http://www.acehardware.com/product/i...ductId=1443552 |
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#7
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On 02/01/2011 12:47 PM, RHF wrote:
On Feb 1, 10:41 am, m wrote: On 11-02-01 11:22 AM, bpnjensen wrote: Question - does the additional Poly tube around the coax diminish the capacity to provide (presumably useful) inductive ground for the buried cable? Seems to me that anything resembling an inductive ground would be a bad thing. The inductive coupling effect would vary completely with the frequency of the signal, proximity, length, etc. Not good. - Don't settle for anything less than a real, - lowest possible impedance, honest to G_d, - mechanically connected ground. - I usually smear the wire connection and - electrode with vaseline after having sandpapered them. - Then do your clamping. - A plastic cup inverted over the end of the - ground rod will keep the rain out of the joint. - - mike Conductive Grease "NO-OX-ID" http://www.sanchem.com/aSpecialE.htm...FRiAgwodThlG2g CRC® Dielectric Grease http://www.acehardware.com/product/i...ductId=1443552 . Heat Sink Compound {Zink Oxide} http://www.radioshack.com/product/in...ductId=2102858 * Rite Aid Zinc Oxide, Ointment http://www.amazon.com/dp/B00009M8JK even remembering using fluoride toothpaste hey - what works... works ! - iane ~ RHF . . You are freaking nuts. |
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