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Author Topic: balanced line and pickup noise  (Read 414 times)
ZL1KMN
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Posts: 99




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« on: November 29, 2006, 11:03:43 AM »

Hi,

Would like to ask how it looks like balanced contra coax from noise point of view?

I have 90deg InvV for 80m RX(balanced line), which is quite noisy. It pick up noise from vertical, but I am detuning it, then it become more silent, but still...
Somehow detuning of the vertical doesnt effect on invV RX...
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K3AN
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Posts: 787




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« Reply #1 on: November 29, 2006, 05:54:58 PM »

Contra coax? You'll have to ask Ollie North.
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ZL1KMN
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Posts: 99




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« Reply #2 on: November 29, 2006, 06:01:48 PM »

Sri, but whats his callsign? Is it the  FOX News Channel guy, antiterrorism expert?
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WW5AA
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Posts: 2086




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« Reply #3 on: November 30, 2006, 09:19:02 AM »

Armin,

I may be wrong, but it seems that you are using a vertical for TX and an inverted "V" for RX. An inverted "V", depending on the angle of the radiators has a large vertical componant when compared to a flat top wire. A better choice would be a low long wire with a lower noise to signal ratio. That is why many low band DXers use a beverage antenna system for directional RX, or a somewhat shorter wire for omni RX. It seems that you have discovered that de-tuning a resonant antenna provids improvement in the signal to noise radio. Have fun!

73, de Lindy  
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ZL1KMN
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Posts: 99




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« Reply #4 on: November 30, 2006, 09:51:37 AM »

Thanks, Thats exactly, what I did...
So, basicly, swapping balanced line to coax will not improve anything...
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KB4QAA
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Posts: 2367




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« Reply #5 on: November 30, 2006, 10:02:20 AM »

Armin,
I can't find anything in any of my antenna books that says balanced feed line is any noisier than coax.  As long as it is kept balanced (not run close to metal, and has as slight twist) it might be quieter than coax since the two lines cancel each other out.

The only thing I can find online is one chap who claims that a horizontal loop had more static build up and atmospheric noise when fed with ladder line.  If both ladderline and coax have proper lightening/static protection I don't see that this would occur.  

Of course the higher the angle on an inverted-V, the more it resembles a vertical, and the more all around noise it will have.   I encourage you to try both feedlines, that is the heart of amateur experimentation!

73, bill

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ZL1KMN
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Posts: 99




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« Reply #6 on: November 30, 2006, 11:16:23 AM »

Thanks Bill,

Will try to make my 90 deg invV as flat as possible, as a first trial...
Thanks for help!

CU on 80m CW.
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W2VW
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Posts: 69




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« Reply #7 on: December 02, 2006, 03:22:00 PM »

You might try grounding the vertrickle antenna while receiving. They can re-radiate noise.
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