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Old October 26th 03, 09:32 PM
Tony Meloche
 
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Default Question for better antenna mavens than I

I am using a 60 ft. random wire with my Icom R-75. The receiver also
has very solid outdoor ground. I get excellent signal pulling ability,
but a lot of noise, too. I have been given 65' of good quality coax.
If I replace the antenna "even-up" as it were, and ground the braid of
the coax to the receiver ground, will it quiet reception as much as I
have a hunch it would? Would it diminish signal gathering potential,
though (I know coax has higher signal loss over a long run.)


Very much appreciate any reply - thanks!

Tony


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Old October 27th 03, 02:04 AM
Mark S. Holden
 
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Tony Meloche wrote:

I am using a 60 ft. random wire with my Icom R-75. The receiver also
has very solid outdoor ground. I get excellent signal pulling ability,
but a lot of noise, too. I have been given 65' of good quality coax.
If I replace the antenna "even-up" as it were, and ground the braid of
the coax to the receiver ground, will it quiet reception as much as I
have a hunch it would? Would it diminish signal gathering potential,
though (I know coax has higher signal loss over a long run.)

Very much appreciate any reply - thanks!

Tony

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The antenna design I suggest looking at is the "Doty antenna".

It involves putting the coax underground, and putting your antenna away from noise sources like the devices in your house and your neighbors homes. It also uses a 9:1 impedance matching transformer.
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Old October 27th 03, 03:39 AM
starman
 
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"Mark S. Holden" wrote:

Tony Meloche wrote:

I am using a 60 ft. random wire with my Icom R-75. The receiver also
has very solid outdoor ground. I get excellent signal pulling ability,
but a lot of noise, too. I have been given 65' of good quality coax.
If I replace the antenna "even-up" as it were, and ground the braid of
the coax to the receiver ground, will it quiet reception as much as I
have a hunch it would? Would it diminish signal gathering potential,
though (I know coax has higher signal loss over a long run.)

Very much appreciate any reply - thanks!

Tony


The antenna design I suggest looking at is the "Doty antenna".

It involves putting the coax underground, and putting your antenna away from noise sources like the devices in your house and your neighbors homes. It also uses a 9:1 impedance matching transformer.


The Doty-L works very well. Here's the URL for it:

http://www.anarc.org/naswa/badx/ante...e_antenna.html


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Old October 27th 03, 06:17 PM
Bill Hennessy
 
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The noise may be comming from other sources that the antenna. Take the
radio to another place and try it out. It might be a power transformer.

Bill, N5NOB


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Old October 28th 03, 12:05 AM
RHF
 
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TM,

What you seam to be describing is an actual Random Wire Antenna with
an outside Ground.

Understanding the Random Wire Antenna . . .
- - - And Building a Better One !

Random Wire Antenna: (External OutSide)
* Piece of Wire used for an Antenna Element
- - - Can be Bare Wire or Insulated Wire.
- - - Not 'cut' to any specific frequency/band.
- - - Simply a 'piece' of wire that fits the available space.
* Piece of Insulated Wire used as the Lead-In Wire from the Antenna
Element to the Radio's HI-Z (500 Ohm) Antenna Terminal.
- - - Connects the Antenna and the Radio.
* Ground with Ground Wire connected to the Radio's Ground Terminal.
- - - Completes the Antenna's path to Ground.
= = = The Result is the Lead-In Wire also acts as a 'part' of the
Antenna. Because the Lead-In Wire is closer to the house/building and
the sources of most 'man made noise'; the Lead-In Wire contributes to
most of the Noise that the Antenna exhibits when listening to the
radio.

YES - Using a Coax Cable as a Lead-In Wire from the Antenna Element to
the Radio; could help in reducing the amount of Noise that is heard on
the radio.
- - - Using a Matching Transformer between the Antenna Element and the
Coax Cable would be a better method of connection.
* Matching Transformer -=V=- Bal-Un "Balun"
http://groups.yahoo.com/group/SWL-AM...nna/message/65

BUT - There is a Better Idea on both Noise Reduction and Signal
Improvement.

When 'considering' what is called a "Random Wire" Antenna ?
Commonly an End-Feed 'longish' piece of wire varying from 30/50Ft to
150/200Ft.
..
Instead 'consider' the "LOW NOISE SWL ANTENNA" [ W H A T ? ]
- - - From the Association of North American Radio Clubs (ANARC)
WebSite and the Rec.Radio.ShortWave (NG) WebPage Presented &
Written by John Doty
* http://www.anarc.org/naswa/badx/ante...e_antenna.html
= JD Quote =
It doesn't take very much wire to pick up an adequate signal for
anything but the crudest Shortwave receiver. The Difference between
a mediocre antenna system and a great antenna system isn't the
antenna itself: it's the way you feed signals from the antenna to
the receiver. The Real Trick with a Shortwave receiving antenna
system is to keep your receiver from picking up noise from all the
electrical and electronic gadgets you and your neighbors have.
=Un-Quote=
..
Link to 'Diagrams' of Several "Low Noise" Antenna Types.
Here is a "Make A Shorter Link" URL-Key to the above Low Noise
Antenna Diagrams:
GoTo= http://makeashorterlink.com/?F1CB12BB4
..
Diagrams of "Random Wire" Antenna using a Balun and Coax FeedLine
* http://www.geocities.com/n2uhc/wire.html
* http://www.kc7nod.20m.com/improved_rw.htm
..
RHF 'says' Here is my Double Nickel (Ten Cents Worth)
on this Very Simple and Basic Low Noise SWL Antenna:
1. 45-200 Feet of 14 AWG Insulated 19 Strand Copper Wire
2. Height of Support Points 15-50 Feet.
3. Bottom Feed Point for both Ground and Coax.
4. Matching Transformer (UnUn)
5. Bury the Coax if possible.
6. Best Antenna 'Form' to Consider is the Inverted "L" Configuration
requiring two relatively 'high' antenna support points.
* http://uweb.superlink.net/bhtongue/12ILAnt/12ILAnt.html
* http://www.antenna.be/il.html
* http://www.hard-core-dx.com/nordicdx.../lantenna.html
-OR- a "Sloper" Configuration requires one higher and one lower
antenna support point (if you only have one high point).
* http://www.alphadeltacom.com/images/dxswl.gif
* http://www.hard-core-dx.com/nordicdx...ire/sloper.gif
* http://www.universal-radio.com/catalog/sw_ant/0013.jpg
..
Here are two 'specialized' wires designed specifically for SWL
Antennas Elements:
* "QuietFlex" Antenna Wire by Antennas & Mo Insulated, Strong,
Flexible and Durable.
GoTo= http://www.antennasmore.com/wire&.htm
"QuietFlex" #14 AWG Antenna Wire has more than 41 Strands tightly
twisted together under its Flexible Insulation making it both
Strong, Flexible and Durable.
* "Flex-Weave" Antenna Wire
GoTo= http://www.radio-ware.com/products/fw.htm
"Flex-Weave" is a hybrid aerial wire that consists of 168 strands of
woven #36 solid copper wires that provide high strength and extreme
flexibility. The most popular version of "Flex-Weave" is
the 'equivalent' of #14 AWG wire size. It can be 'used' for
unsupported spans up to 200 ft (100-150 ft in areas with high ice
and wind loading).
..
Consider the ICE 180 that is not only a Matching Transformer but a
Lightening Surpressor
* http://www.hard-core-dx.com/nordicdx...ed/ice180.html
This Hard-Core-Dx.Com WebPage Presented and Text Written by John
Doty
=JD Quote=
A Matching Transformer at the Base of the Antenna can smooth out the
fluctuations in antenna system efficiency with frequency, yielding
an Antenna System that Works well enough for good reception from
LongWave to the top of the ShortWave Range.
=Un-Quote=
Here is a Do-It-Yourself Matching Transformer
* http://www.kc7nod.20m.com/new_page_1.htm
..
..
iane ~ RHF
I Ain't No Elmer !
..
..
NOTE: This was basically a 'copy' of Message #2 and #119 posted on
the SWL Antennas and AM& FM Antennas eGroup on YAHOO!
http://groups.yahoo.com/group/SWL-AM...enna/message/2
http://groups.yahoo.com/group/SWL-AM...na/message/119
http://groups.yahoo.com/group/SWL-AM...nna/message/29
http://groups.yahoo.com/group/SWL-AM...nna/message/65
..
..
= = = Tony Meloche
= = = wrote in message ...
I am using a 60 ft. random wire with my Icom R-75. The receiver also
has very solid outdoor ground. I get excellent signal pulling ability,
but a lot of noise, too. I have been given 65' of good quality coax.
If I replace the antenna "even-up" as it were, and ground the braid of
the coax to the receiver ground, will it quiet reception as much as I
have a hunch it would? Would it diminish signal gathering potential,
though (I know coax has higher signal loss over a long run.)


Very much appreciate any reply - thanks!

Tony




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Old October 28th 03, 01:25 AM
Tony Meloche
 
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My thanks to all who replied. I had a chance today (rare day off)
to try a few experiemnts of my own, and decided my original 60' random
wire - with the new addition of a coax drop to the antenna terminal,
rather than being end fed by the antenna itself - was my best solution.

Fortunately, I live "out in the country", and have only one close
neighbor - if you want to call 100 yards away "close". Ambient noise is
not as much of a problem for me as it would be for some.

Tony


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Old October 28th 03, 04:33 AM
Private
 
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Hello Tony,

I have been into SWL'ing for roughly 15 years and have tried several
types of wire antenna. My suggestion would be to run the coax from
the radio outdoors, once outside attach the braid to an exterior
ground (i.e. ground rod driven in 8-10 feet). Then run your random
wire and attach to the centre of the coax.

I used to run 102' of 8U coax and found no issues with loss.


Tony Meloche wrote in message ...
I am using a 60 ft. random wire with my Icom R-75. The receiver also
has very solid outdoor ground. I get excellent signal pulling ability,
but a lot of noise, too. I have been given 65' of good quality coax.
If I replace the antenna "even-up" as it were, and ground the braid of
the coax to the receiver ground, will it quiet reception as much as I
have a hunch it would? Would it diminish signal gathering potential,
though (I know coax has higher signal loss over a long run.)


Very much appreciate any reply - thanks!

Tony


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Old October 28th 03, 10:16 AM
RHF
 
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TM,

To put it simply: Every Antenna 'resonates' !

Every "Random Wire Antenna is a Full Wave Length (WL); a Half WL and a
Quarter WL at some frequency. The trick is to make the Random Wire
Antenna more Broad Banded and improve the overall 'reception'
performance across the SWL Bands.

"Actually, a fixed matching transformer can dramatically reduce the
wild swings in antenna efficiency that a coax fed wire antenna
exhibits." - - - John Doty
http://www.anarc.org/naswa/badx/ante..._longwire.html

iane ~ RHF
..
..
= = = Tony Meloche
= = = wrote in message ...
My thanks to all who replied. I had a chance today (rare day off)
to try a few experiemnts of my own, and decided my original 60' random
wire - with the new addition of a coax drop to the antenna terminal,
rather than being end fed by the antenna itself - was my best solution.

Fortunately, I live "out in the country", and have only one close
neighbor - if you want to call 100 yards away "close". Ambient noise is
not as much of a problem for me as it would be for some.

Tony


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