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Author Topic: New (old) antenna up at my QTH  (Read 1492 times)

Offline Tom S

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New (old) antenna up at my QTH
« on: October 22, 2012, 1500 UTC »
My main HF listening antenna for the past year or so has been a ~150 ft. random wire up between two trees on my property.  I'd been noticing that it wasn't very effective at the upper ranges of the HF spectrum so decided to resurrect my old Cushcraft trap vertical.  When we first moved in here I had it up on a corner of the house, but I had so much noise there (probably due to its proximity to power lines on the north side of the house and not having a good ground) I had about an S9 noise floor but little signal.  This weekend I put it up next to the garage and it is working great.  I still need to run a few ground radials, install a grounding rod, and get about 100' of coax and run it properly under the eaves of the house and garage rather than the just-long-enough coax running across the ground from the window to the house.  But for now it works.

I built a switchbox to be able to switch between either the wire or the vertical, and to switch both of them in together if I want.  I've found that on some signals with selective fading, it helps to have both antennas connected since sometimes the horizontal polarity fades but comes in strong vertically, and vice-versa.  I've noticed that signals which were coming in OK on just one antenna really jump up a few S-units when both are switched in.  This is what I learned in the military is called polarity diversity.  There's also the advantage of space diversity, but my two antennas probably aren't far enough apart to take advantage of that.

At any rate, I should be able to pick up signals in the upper HF spectrum better.  With the 10/11 meter opening this weekend, I definitely noticed a difference between the vertical and the wire.
Happiness is a good antenna system.

Offline weaksigs

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Re: New (old) antenna up at my QTH
« Reply #1 on: January 25, 2013, 2216 UTC »
Currently at my location in central Florida I'm using a 196 foot random wire.
Recently I connected at the entrance end a 9:1 Z toroid balun using
low to middle hf  range material. Can't remember the exact material mix
but can procure if it . The naked random wire performed great across the
spectrum including down into the NDB band and below 180Khz for longwave.

Adding the toroid (primary high z/ coax cable secondary) with ground before
entering the house raised all of the lower frequency <10Mhz +/-)  a good
bit. One example is NDB beacon CLB which is a conveniently placed signal
being about 480 miles away. Adding the toroid as briefly described brought
up CLB from a nominal 7 microvolts during the day to over 10 microvolts with
a reduction of overall noise level.

All in all there may be some befit to isolating the wire, grounding well and
attempting to keep noise out of the antenna system.

Just a quick though or two for you!!!

weaksigs
Central Florida
136' random wire for general HF,
Winradio Excalibur G31 & Kenwood TS-590

Peace!

Nella F.

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Re: New (old) antenna up at my QTH
« Reply #2 on: January 25, 2013, 2354 UTC »
Antenna in trees, how I miss those days.