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Author Topic: Noise reduced antenna  (Read 1335 times)

rdla4

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Noise reduced antenna
« on: August 12, 2012, 2231 UTC »
I have had BAD RFi all summer, I have been using a MFJ Noise Cancelling box to help some what. Since the temperatures were approaching sane levels of heat during the day, this weekend, i spent the day taking down the longwire, and put up a pendant antenna. Each side of the pendant is about 80 feet long, and the 'short side ' is roughly 45 feet. I did not do any measurements on it, I just installed it where I had two good trees.

What a difference! This antenna is MUCH quieter vs the longwire. I had been feeding the LW with an Un-Un, the pendant is using a cheap Cable TV 75 to 300 balun.  Disconnecting the 'shortside" in the middle causes a big increase in noise, and no change in desired RF. I had not been able to hear much in the 31Meter band since April. Even strong signals were buried by the 20 over S9 noise. The MFJ would bring it down to about S9. I am listening to some weak signals on 31M this afternoon. I still need to the MFJ to null the noise, but weak signals are now listenable.

I had a quiet S2 signal from CFRX in Toronto on 6070 in the middle of the afternoon....could not be done on the Longwire.

Cant wait to see what I can now hear on 6925.



Offline ChrisSmolinski

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Re: Noise reduced antenna
« Reply #1 on: August 12, 2012, 2239 UTC »
Great to hear the positive results!

I wonder if the low noise is due, at least partly to the pennant antenna being a loop? My experience (and I've read in numerous times elsewhere as well) is that loop antennas are inherently low noise. I noticed this when I put up a T2FD several years ago. And thinking back, I had a folded dipole back in the 80s, and that also performed very well.

Chris Smolinski
Westminster, MD
eQSLs appreciated! csmolinski@blackcatsystems.com
netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 900 ft Horz skyloop / 500 ft NE beverage / 250 ft V Beam / 58 ft T2FD / 120 ft T2FD / 300 ft south beverage / 43m, 20m, 10m  dipoles / Crossed Parallel Loop / Discone in a tree

rdla4

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Re: Noise reduced antenna
« Reply #2 on: August 12, 2012, 2321 UTC »
Yes, the loop does make it quiet. At the half way point, I opened the antenna up, noise came up desired signals show no real change. Put the wire back together, and the local noise came way way down.