HFU HF Underground
Technical Topics => Equipment => Topic started by: Erik Mattson on January 05, 2022, 1435 UTC
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Surely someone has tried laying a magnetic loop horizontally. Just for S&Gs...? What does that do to reception?
I've never used one at all, but I know do theres a null through the middle. That is, if you're seeing a donut, consider yourself nulled.
And I know, and agree that, antennas belong outside, and that's where mine usually go, but I've been meaning to stick something in my attic.
I say "attic", but for the most part it's more like a crawlspace, about two foot in height. And that got me thinking about what sorta antennas I could stick up there. Just for the hell of it. My first thought was a Slinky Dipole, my third was a loop. But all horizontal like.
Oh, and while I've got ya: Is there a length limit for powering with a bias-tee connection?
Thoughts?
Thanks,
Erik
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It is not uncommon to see loops installed at a 45 degree angle in order to optimize both horizontally and vertically polarized radio waves.
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The length limit to the bias tee is the voltage drop due across the length of coax; just like DC on any regular wire. I would not be too concerned unless you are going to be running like a couple of hundred feet or more of feedline, as at moderate lengths, it is not a big deal if you lose like 0.5-1 volt. Preamps tend to have a moderately wide operating ranges for supply voltages anyway.
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A couple of options for the BIAS-T.
1. You could use a better quality feed line with lower loss. For example, the direct-to-home satellite industry has been doing this for years using quality RG-6 to power and tune the LNBs/LNBFs.
2. You do not need to install the external power inserter directly at the receiver. The power inserter can be located anywhere closer to the antenna.
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Thank you both, for the help. Thankfully, the RSPdx makes it easier as far as the bias-t goes. And I think Chris and others have convinced me to stop spending extra money and go with RG-6. From attic to cave (basement) would only need about a 50 foot run.
Put together a Slinky dipole yesterday. Don't know if it was worth the trouble, but it looks neat anyway. Think I'll stick that up there as well.
Thanks again.
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No prob with 50' of RG-6. :) I have a couple of similar length runs with bias tees for my active miniships, and I use inexpensive RG-6 from the big box hardware stores for most of my receiving antennas.
Copper-clad steel RG-6 feedline might have some loss at like 160m, MW, and lower due to how skin effect works, but those bands are dominated by atmospheric noise anyway, so a few dB loss down there is not a big deal for receiving IMO.