Co-ax chokes?
 

Hi all!
Was wandering round RHC's site (Thanks for the reminder Mike!)
and came accross this...

http://www.radiohc.org/Distributions/Dxers/coax-rf.html

........ now, I have a random long wire, ungrounded, down the back
garden. A run of RG58 taking it through the window frame and to the radio
via a howes atu. Would one of these air wound chokes help at the antenna
end? Does anyone have any experience of these?

Les

--
http://www.stuffmongers.com

"Homo sapiens, the first truly free species, is about to decommission
natural selection, the force that made us.... Soon we must look deep within
ourselves and decide what we wish to become."
Edward O. Wilson
Consilience, The Unity of Knowledge

Remove frontal lobes to reply from a NG

"Les &/or Claire" wrote in message
...
Hi all!
Was wandering round RHC's site (Thanks for the reminder
Mike!)
and came accross this...

http://www.radiohc.org/Distributions/Dxers/coax-rf.html

........ now, I have a random long wire, ungrounded, down the back
garden. A run of RG58 taking it through the window frame and to the radio
via a howes atu. Would one of these air wound chokes help at the antenna
end? Does anyone have any experience of these?

Les

--
Unless you have grounded the shield of the coax- it is and will continue
to act as part of the antenna. Air wound chokes can be very efficient- but
over a relatively narrow bandwidth. Probably the 1st thing to do is to put a
classic 9:1 or 10:1 transformer at the antenna to smooth out Z gyrations and
to ground the shield at the antenna.

W4OP

LES,

For a Receiving "Only" Antenna with a few feet of 'extra' Coax
in the Feed-in-Line: Can't Hurt and just may Help !
http://www.radiohc.org/Distributions/Dxers/coax-rf.html

1. Six to Eight 10"-12" Air Coils (about 20-25Ft of Coax)
is easy enough to do as a simple RF-Choke experiment.

2. If you do not have the 'extra' 20-25Ft of Coax currently in
your Feed-in-Line then you could use a small 6"-8" piece of PVC
Pipe as a Coil Form and use a Dozen or so closely wrapped smaller
coils as an RF-Choke. Requires about 3Ft of 'extra' Coax.

3. A Third "Option" is to find 3-6 Six to Eight Inch Ferrite
Rods and Tape then 'together' in a Bundle . Next "Wrap" the
Coax around the Ferrite Rod Bundle just like the PVC Example #2.

FWIW: I 'recommend' a 9:1 Matching Transformer and a Grounding Point
at the "Junction" of the Antenna Element and the Coax Cable.

Read these three Links 'presented' by John Doty:
[ Hosted by The Association of North American Radio Clubs "ANARC".]

Longwire Impedance Matching. {Check-Out the Graphs}
http://www.anarc.org/naswa/badx/ante..._longwire.html
Actually, a fixed Matching Transformer can dramatically reduce the
wild swings in Antenna Efficiency that a Coax Fed Wire Antenna exhibits.

Grounding is the KEY to Good Reception
http://www.anarc.org/naswa/badx/antennas/grounding.html

Low Noise Antenna Connection
http://www.anarc.org/naswa/badx/ante...e_antenna.html
..
..
Some Say: On A Clear Day You Can See Forever.
http://groups.yahoo.com/group/SWL-AM...na/message/502
I BELIEVE: On A Clear Night...
You Can Hear Forever and Beyond, The Beyond !
..
..
= = = "Les &/or Claire" wrote in message
= = = ...
Hi all!
Was wandering round RHC's site (Thanks for the reminder Mike!)
and came accross this...

http://www.radiohc.org/Distributions/Dxers/coax-rf.html

........ now, I have a random long wire, ungrounded, down the back
garden. A run of RG58 taking it through the window frame and to the radio
via a howes atu. Would one of these air wound chokes help at the antenna
end? Does anyone have any experience of these?

Les

--
http://www.stuffmongers.com

"Homo sapiens, the first truly free species, is about to decommission
natural selection, the force that made us.... Soon we must look deep within
ourselves and decide what we wish to become."
Edward O. Wilson
Consilience, The Unity of Knowledge

Remove frontal lobes to reply from a NG
..