coax loop
Brian
Anyone familiar with this particular antenna? Have you had success? Is it
necessary to use an antenna tuner? Just curious.
-Brian
Frank Halaburak
telescope tripod for
rotating it to null out noise. it's pretty good. It even works for
mediumwave.
73, Frank
"Brian" <imagina...@whatthefuck.com> a écrit dans le message de
news:U0Ged.6046$5i5....@newsread2.news.atl.earthlink.net...
Telamon
"Brian" <imagina...@whatthefuck.com> wrote:
This is a shielded loop.
The author specifies a 1 inch gap in the braid but I don't think that
gap size is important. The gap needs to be wide enough that it never
accidentally gets shorted. If it shorts the loop output will go to zero.
If the gap is larger then necessary then the loop is partly unshielded.
You don't have to use a tuner but this antenna is low output so the
tuner is used to peak the output so you get more out of it. Another
alternative is to use an amplifier. The amplified loop does not need to
be tuned so it's more convenient but it will not be a quiet as the tuned
loop.
--
Telamon
Ventura, California
RHF
= = = news:<U0Ged.6046$5i5....@newsread2.news.atl.earthlink.net>...
BRIAN,
I built one of these Coax Cable [Shielded] Loop Antennas for
the 60 Meter Shortwave Band; my intended Lowest Frequency:
- 4.75 MHz to 5.06 MHz with a MidPoint of 4.905 MHz
- Cut to 13.5 Feet [1/10WL] VF=0.66 using RG8 Coax Cable.
- Square shape 3.4 Feet per Side with 4.8 Cross-Arms.
- Round shape 4.3 Diameter Circle.
- Coax Cable Lead-in-Line 5 Feet.
This Coax Cable [Shielded] Loop Antenna is very 'quiet' and
work very well if you are limited to an InDoor Antenna ONLY.
I tried using a Tuner {Pre-Selector} with it; but with my
Icom IC-R75 and Kenwood R-5000 Receivers the Tuner proved
to be un-necessary.
* The Coax Cable [Shielded] Loop Antenna can be used to
NULL-OUT 'local' RFI/EMF man made Noise within the house.
* For the Shortwave Band Frequencies above 5 MHz to 25 MHz
the Coax Cable [Shielded] Loop is an NON Directional Antenna.
* For the AM/MW Broadcast Band (530 kHz to 1700 kHz) it becomes
a Directional Antenna and the use of a Tuner {Pre-Selector} helps.
TIP: I used some 5/8" or 3/4" (White) Low Pressure Water Line
Polyethylene Tubing as a "Form" to hold the Loop in a Circle Shape.
Sort of like a Big Hula Hoop. Build your Loop and just before
you are ready to assemble at the bottom; slide the Coax through
the Polyethylene Tubing. Cut the Polyethylene Tubing so that it
is about 2" shorter than the Circumference of the Coax: This is
to leave 'room' to make the Bottom "Joint" to Complete the Loop.
Shape-Out the Polyethylene Tubing so that it is a Circular Loop.
Finally make the Bottom Coax Shield {Connection} Joint.
FWIW: Sometimes when using this Loop with the Icom IC-R75,
I will have a clear and listenable Signal with NO 'apparent'
S-Meter Reading. The Signal is so quiet that I can use the
#2 Pre Amp and still have a Cleaner and More Listenable Signal
then by using my 75 Foot Low Noise Inverted "L" Antenna. The
Inverted "L" will have an S-7 to S-9+10dB S-Meter Reading, but
the background noise level will be S-2 to S-4 and a small
amount of noise can be heard with the program audio.
SUMMARY: An "Easy-to-Make" Coax [Shielded] Loop Antenna.
A very good Antenna for SWLs with Noise Problems and who
are 'limited' to InDoor Antennas ONLY. Makes a nice Second
Antenna for dealing with some types of Reception Problems.
NOTE: I would make my next one with RG58 or Mini RG8.
RECOMMENDATION: If you are going to use one of these Coax
[Shielded] Loop Antennas InDoors with an OutSide Antenna with
a single Radio/Receiver. Buy a 'quality' Antenna Switch like
the MFJ-1702C; Alpha Delta 2; Daiwa CS-201 and others.
http://www.mfjenterprises.com/products.php?catid=122
http://www.universal-radio.com/catalog/switch/2415alt.gif
http://www.durhamradio.com/s/customer/home.php?cat=1606
http://www.universal-radio.com/catalog/switch/2811.html
These will allow you to 'switch' between Antennas; and they
automatically "Ground-Out" the Un-Used Antenna. Also these
Antenna Switches have a "Center" position that "Disconnects
and Grounds both the Antennas when the Radio/Receiver is
not-in-use. {A Nice Safety Feature.}
iane ~ RHF
.
Some Say: On A Clear Day You Can See Forever.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/502
I BELIEVE: On A Clear Night . . .
You Can Hear Forever and Beyond - The Beyond !
.
.
bpnjensen
> = = = "Brian" <imagina...@whatthefuck.com> wrote in message
> = = = news:<U0Ged.6046$5i5....@newsread2.news.atl.earthlink.net>...
> >
> > http://www.greertech.com/hfloop/mymagloop.html
> > Anyone familiar with this particular antenna ?
> > Have you had success ?
> > Is it necessary to use an antenna tuner ?
> > Just curious.
> >
> > -Brian
>
>
> BRIAN,
>
> I built one of these Coax Cable [Shielded] Loop Antennas for
> the 60 Meter Shortwave Band; my intended Lowest Frequency:
> - 4.75 MHz to 5.06 MHz with a MidPoint of 4.905 MHz
> - Cut to 13.5 Feet [1/10WL] VF=0.66 using RG8 Coax Cable.
> - Square shape 3.4 Feet per Side with 4.8 Cross-Arms.
> - Round shape 4.3 Diameter Circle.
> - Coax Cable Lead-in-Line 5 Feet.
>
> This Coax Cable [Shielded] Loop Antenna is very 'quiet' and
> work very well if you are limited to an InDoor Antenna ONLY.
<good stuff snips>
RHF - is there any reason why this antenna could not be adapted for
outdoor use? Good construction, some simple weatherproofing and
mounting on a rotator with plenty of slack coax for turning should
give a unit that could stand up fairly well, right?
Bruce Jensen
RHF
= = = news:<37af7e1c.0410...@posting.google.com>...
> > = = = "Brian" <imaginaryfriend@wh*tth*f*ck.c*m> wrote in message
> > >
> > > http://www.greertech.com/hfloop/mymagloop.html
> > > Anyone familiar with this particular antenna ?
> > > Have you had success ?
> > > Is it necessary to use an antenna tuner ?
> > > Just curious.
> > >
> > > -Brian
> >
> >
> > BRIAN,
> >
> > I built one of these Coax Cable [Shielded] Loop Antennas for
> > the 60 Meter Shortwave Band; my intended Lowest Frequency:
> > - 4.75 MHz to 5.06 MHz with a MidPoint of 4.905 MHz
> > - Cut to 13.5 Feet [1/10WL] VF=0.66 using RG8 Coax Cable.
> > - Square shape 3.4 Feet per Side with 4.8 Cross-Arms.
> > - Round shape 4.3 Diameter Circle.
> > - Coax Cable Lead-in-Line 5 Feet.
> >
> > This Coax Cable [Shielded] Loop Antenna is very 'quiet' and
> > work very well if you are limited to an InDoor Antenna ONLY.
>
> <good stuff snips>
>
> RHF - is there any reason why this antenna could not be adapted for
> outdoor use? Good construction, some simple weatherproofing and
> mounting on a rotator with plenty of slack coax for turning should
> give a unit that could stand up fairly well, right?
>
> Bruce Jensen
BJ,
It is my understanding that the Coax Cable Lead-in-Line can not
be to long. If as you say, you used good construction techniques
and Weather Proofed everything then it should work OK OutSide.
ROTOR:
The "Rotor" should work OK for 'Peaking' and 'Nulling-Out'
Signal in the AM/MW Broadcast Band and to some degree in the
Shortwave Bands below 5 MHz. IMHO: Above 5 MHz the Rotor
may not do much good. For 'local' Man-Made-Noise RFI/EMF
InDoors or OutSide; usually once you Null-it-Out you need not
move or position the Loop Antenna Element again.
PRE-AMPLIFER:
I would think that using a Pre-Amplifier in the Feed-in-Line
about 'one diamerter' from the Loop Antenna Element might make
the whole thing work a lot better.
FWIW: I just tried a RadioShack Catalog # 15-1118B TV=-VCR-FM
10dB Signal Amplifier and it gave a 'boost' of about S-5 to S-7
in the AM/MW Band and across the Shortwave Bands.
- Listenable Signals in the S-1 to S-2 range became S-7 to S-9
and easy to listen to.
- Very 'weak' (faint) Signals in the No S-Meter reading (S-Zero)
became Listenable at S-5 to S-7.
iane ~ RHF
.
Telamon
bpnj...@yahoo.com (bpnjensen) wrote:
Any antenna will work better outside. The only difference between an
outdoor and an indoor is weather proofing and the strength to stand the
elements.
--
Telamon
Ventura, California