Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
RHF
Single Wire Antenna {Longwire / Random Wire Antenna}
What To Use : Antenna Tuner? and/or Pre-Selector?
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/7161
ANTENNA TUNERS :
For a Radio/Receiver operating over a wide frequency spectrum
using a single length of Wire as the Antenna Element.
The Antenna Tuner will allow you to Match (Tune) the Impedance
of the Antenna and to Match (Tune) the Impedance of the
Radio/Receiver Antenna Input. The Antenna Tuner is often
and Interactive Device in which the Movement of One Control
will require the Movement (large or small) of another Control
(s); followed by a minor adjustment of both. Antenna Tuners
are most often used when you are changing from one Shortwave
Frequency Band to another. With a Shortwave Band change you
will usually find that you will have to adjust the Antenna
Tuner to get the Best Match (Highest S-Meter Reading) between
the Antenna and Radio. Within a given Shortwave Frequency
Band - once set the Antenna Tuner may need no other adjustment.
However, when using an Antenna Tuner in the Medium Wave (AM-BCB)
you may find that you have to retune for each new Radio Station
Frequency throughout the Band. If a 9:1 Matching Transformer
is used between the Antenna and a Coax Cable Feed-in-Line :
Then often with Modern AM/FM Shortwave Radios an Antenna Tuner
is not needed. Note - Antenna Tuner Circuits and Designs
come in many Flavors.
PRE-SELECTORS :
The Pre-Selector can be thought of as a Variable "Narrow"
Band Pass Filter. The Radio Operator uses the Pre-Selector
to 'selectively' "Pre-Choose" a very Limited Range [Band] of
Frequencies to "Feed" Pass-InTo the Radio/Receiver. All other
Out-of-Band-Width Frequencies are Attenuated to some degree
by the Pre-Selector. If a 9:1 Matching Transformer is used
between the Antenna and a Coax Cable Feed-in-Line : Then a
Pre-Selector will usually work very well and provide some
benefit with most Modern AM/FM Shortwave Radios.
IMHO - For the Shortwave Listener (SWL) using a Receive Only
Random Wire (Single Wire) Antenna the Pre-Selector is the
better of the two devices to use. Especially when used in
conjunction with a 9:1 Matching Transformer along with a
Coax Cable Feed-in-Line.
hope this helps - iane ~ RHF
Shortwave Listener's (SWL) Antenna Group on YAHOO !
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/
.
.
. .
= = = In Shortwave-...@yahoogroups.com,
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/6907
= = = "olsons98" <olsons98@ * # $ % > wrote:
1) I wish to erect an antenna in my attic to be used for
SW Dxing (possibly for MW but right now I use a Torus Tuner
and a RF-2200).
Any suggestions for homebrew or commercial antennas?
I want to keep it simple.
2) I'm confused on antenna tuner and preselector theory.
I always though tuners adjusted the electrical length
of the antenna hence selecting the frequency desired.
Once that was accomplished, the preselector would further
define the exact frequency.
I guess I was wrong. The tuner corrects the impedance
and the PS defines the frequency?
I need an example in order to understand there respective applications.
Let's say you have a long wire.
How would you install both a tuner and PS and how does
each affect the performance of the antenna.
Thanks
Phil
.
.
. .
.
David
wrote:
You don't need either one unless your radio has a wide-band front-end.
David
wrote:
Or is a ''single-conversion POS''...
dxAce
David wrote:
You're some kind of POS, 'tard boy. Not sure if you're single-conversion or not.
Now run along and tote, boy.
dxAce
Michigan
USA
RHF
need that something extra ~ RHF
David
wrote:
A lot of that stuff causes more trouble than it solves.
RHF
to pick their Radio / Receivers / Equipment and
decide what works best for them - It's a matter of
choice and personal preference ~ RHF
.
.
. .
.
Bob Miller
wrote:
>
>IMHO - For the Shortwave Listener (SWL) using a Receive Only
>Random Wire (Single Wire) Antenna the Pre-Selector is the
>better of the two devices to use. Especially when used in
>conjunction with a 9:1 Matching Transformer along with a
>Coax Cable Feed-in-Line.
The 9-1 matching transformer works great if the antenna impedance is
450 ohms and it is being matched to a 50 ohm antenna input, a 9 to 1
transformation. But what if the impedance of the antenna is 2000 ohms,
or 10 ohms or 800 ohms? It's a crapshoot with a long wire, because you
don't know what the impedance really is.
An antenna tuner, on the other hand, can be varied to match a wide
range of antenna impedances to a 50 ohm input.
bob
k5qwg
David
wrote:
>On 27 Dec 2005 13:03:44 -0800, "RHF" <rhf-new...@pacbell.net>
>wrote:
>
>
>>
>>IMHO - For the Shortwave Listener (SWL) using a Receive Only
>>Random Wire (Single Wire) Antenna the Pre-Selector is the
>>better of the two devices to use. Especially when used in
>>conjunction with a 9:1 Matching Transformer along with a
>>Coax Cable Feed-in-Line.
>
>The 9-1 matching transformer works great if the antenna impedance is
>450 ohms and it is being matched to a 50 ohm antenna input, a 9 to 1
>transformation. But what if the impedance of the antenna is 2000 ohms,
>or 10 ohms or 800 ohms? It's a crapshoot with a long wire, because you
>don't know what the impedance really is.
>
>An antenna tuner, on the other hand, can be varied to match a wide
>range of antenna impedances to a 50 ohm input.
>
>bob
>k5qwg
>
>>
True, but for a modern receiver insignificant.
The main thing is that you're not exceeding the impedance of the
transmission line.
Bob Miller
And the impedance of the transmission line is ... ???
bob
k5qwg
RHF
The Topic has move to the "Impedance of the Transmission Line"
IIRC - If the Matching Transformer is used and the Secondary Side
of the Matching Transformer exhibits a nominal Impedance of 50 Ohm;
and is connected to a 50 Ohm type Coax Cable; that is connected to
a Receiver's 50 Ohm Antenna Input.
The Coax Cable for all practical purposes is not a significant part
of the Impedance Relationship (Ratio) between the Antenna and
the Receiver's Antenna Input.
The Primary of the Matching Transformer 'helps' to smooth-out
the variations in Impedance of the Antenna due to changes in
Frequency with respect to the Receiver's Antenna Input Circuit.
The Impedance Matching improvement is far from perfect :
But the Dynamic Range of the Front-Ends of most Modern
Shortwave Receivers can easily compensate for any signal
lost due to Impedance Miss-Matches between the Antenna
and the Receiver's Antenna Input Circuit.
hey I could be wrong - cause iane ~ RHF
Bob Miller
wrote:
>Hello - Calling R2000SW and Telamon Where Are You ? ?
>
>The Topic has move to the "Impedance of the Transmission Line"
>
>IIRC - If the Matching Transformer is used and the Secondary Side
>of the Matching Transformer exhibits a nominal Impedance of 50 Ohm;
>and is connected to a 50 Ohm type Coax Cable; that is connected to
>a Receiver's 50 Ohm Antenna Input.
>
>The Coax Cable for all practical purposes is not a significant part
>of the Impedance Relationship (Ratio) between the Antenna and
>the Receiver's Antenna Input.
>
>The Primary of the Matching Transformer 'helps' to smooth-out
>the variations in Impedance of the Antenna due to changes in
>Frequency with respect to the Receiver's Antenna Input Circuit.
Only point I was making is the impedance of the antenna could be
anywhere from a few ohms to thousands of ohms. A 9-to-1 balun between
the antenna and a 50 ohm transmission line only helps if the antenna
is in the neighborhood of 450 ohms.
>
>The Impedance Matching improvement is far from perfect :
>But the Dynamic Range of the Front-Ends of most Modern
>Shortwave Receivers can easily compensate for any signal
>lost due to Impedance Miss-Matches between the Antenna
>and the Receiver's Antenna Input Circuit.
With that much dynamic range, why use a balun at all?
>
>hey I could be wrong - cause iane ~ RHF
I can be wrong, too. Antennas are complicated beasts :-(
bob
k5qwg
David
wrote:
RG-58 is 50 Ohms, RG-59, RG-6 is 75 Ohms.
David
wrote:
So you don't put high Z signal into a lower-Z cable. Major faux pas.
500 Ohms is assumed to be about the max for a wire antenna, no?
Bob Miller
It can be much higher. Looking at the book "Wire Antennas" by William
Cowan, W6SAI, and his chapter on end fed wires:
"In the case of a random length, end-fed antenna, the radiation
resistance at the feed point can vary over a large range, depending on
the operating frequency and the actual length of the antenna. The
measured radiation resistance can be as high as 5000 ohms or as low as
2 or 3 ohms..."
That's why I wonder about the popularity of these 9-to-1 baluns.
One of my antennas is a 20 meter end fed wire, and I tune it with an
old Heathkit AC-1 antenna tuner, which is made especially for random
length, end fed wires. A modern equivalent would be something like the
MFJ-16010 random wire tuner, which at $49.95 doesn't cost much more
than some of the 9-1 baluns I see advertised :-)
It would require bringing the random wire into your residence, and
then running a short length of coax from the tuner to the receiver. I
understand some wouldn't like that because of in-house noise, but
there are always trade-offs to anything.
bob
k5qwg
Sanjaya
"Bob Miller" <NOS...@neosoft.com> wrote in message news:jq75r1digtt2063dc...@4ax.com...
[snip]
> One of my antennas is a 20 meter end fed wire, and I tune it with an
> old Heathkit AC-1 antenna tuner, which is made especially for random
> length, end fed wires. A modern equivalent would be something like the
> MFJ-16010 random wire tuner, which at $49.95 doesn't cost much more
> than some of the 9-1 baluns I see advertised :-)
>
> It would require bringing the random wire into your residence, and
> then running a short length of coax from the tuner to the receiver. I
> understand some wouldn't like that because of in-house noise, but
> there are always trade-offs to anything.
>
> bob
> k5qwg
>
Is there a detailed description, with possible diagrams, explaining how to strip,
connect coax and a random wire... i.e. no balun, direct random wire to coax
connection (coax leading into tuner after that)
David
wrote:
>
>"In the case of a random length, end-fed antenna, the radiation
>resistance at the feed point can vary over a large range, depending on
>the operating frequency and the actual length of the antenna. The
>measured radiation resistance can be as high as 5000 ohms or as low as
>2 or 3 ohms..."
>
I don't think you'll get the kilo-Ohms unless you're under a quarter
wave at the frequency of interest.
RHF
ABOUT - The "Low Noise" Antenna Design Concepts
that were popularized by John Doty :
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/5178
http://groups.google.com/group/rec.radio.shortwave/msg/a438b087b5e89fee
Shortwave Listener (SWL) Longwire Antenna - by John Doty
? WHY Use a Fixed Matching Transformer ?
http://www.anarc.org/naswa/badx/antennas/SWL_longwire.html
hope this helps - iane ~ RHF
Shortwave Listener's (SWL) Antenna Group on YAHOO !
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/
Bob Miller
That's easy. Cut off about 3 or 4 inches of the outer black jacket.
Then use small scissors to split the exposed braid, and cut it off.
Then use a razor blade, box cutter, exacto knife or some other sharp
instrument to peel the plastic insulation off the wire center
conductor. Then take that exposed wire and twist it to your random
wire antenna. Make sure the connection is strong mechanically and
won't work loose.
bob
k5qwg
Bob Miller
wrote:
An antenna tuner will still work better than the balun at impedance
transformation because the tuner is variable and can be peaked
precisely for each listening frequency. The balun is good for one
impedance, and one impedance only, so it's effectiveness is a crap
shoot, since the average listener has no earthly idea what the
antenna's impedance really is.
9-1 baluns mainly benefit the people who charge $29.95 an $39.95 and
up for them...
bob
k5qwg
David
wrote:
>On 28 Dec 2005 08:15:12 -0800, "RHF" <rhf-new...@pacbell.net>
$17.50?
I've used both (tuners and passive matching). Tuners are more trouble
than they're worth, IMHO.
Sanjaya
Thanks Bob. That's just what I needed to know.
RHF
1. Cut off about 3 or 4 inches of the outer black jacket.
2. Use a small Ale to pick open a Hole in the Weave of the Wire
Braided Shield.
3. Carefully use the Ale to Manipulate the Inner Insualtion and
Conductor through the Hole.
4. Smooth-Out the Wire Braided Shield and Twist it in to a Pig Tail.
5. Then use a razor blade, box cutter, exacto knife or some other
sharp instrument to peel about One to Two Inches of the plastic
insulation off the wire center conductor.
6. Then take that exposed wire and twist it to your Wire Antenna
Element. Make sure the connection is strong mechanically and won't
work loose. Tip - Soldering makes for a good Electrical and Mechanical
Connection. Tape-Over-Seal the Connection.
7. Install a Ground Rod with Ground Radial Wires.
( 8 ). Connect the Coax Cables Wire Braided Shield {Pig Tail} to the
Ground Rod. Tape-Over-Seal the Connection.
Remember - You Are Always Behind The Eight Ball With Out A Ground
Connection.
Coax Cable Stripping - How To
http://www.swhowto.com/CoaxStrip.htm
http://www.chantalcurrid.com/Remote/Images/PWires.jpg
http://homepages.tesco.net/~gary.aylward/graphics/CoaxStrip.jpg
http://homepages.tesco.net/~gary.aylward/graphics/CoaxAssy.jpg
http://www.benelec.com.au/coax_conns/image/Strip_draw2.gif
hope this helps - iane ~ RHF
David
wrote:
That method of connecting is lame. You'll likely get no advantage
over running the wire straight to your receiver.
Sanjaya
"RHF" <rhf-new...@pacbell.net> wrote in message
news:1135876820.4...@z14g2000cwz.googlegroups.com...
RHF... R eally H elpful F undamentals... as always.
Thanks millions and Happy New Year.
Sanjaya
nm...@wt.net
>measured radiation resistance can be as high as 5000 ohms or as low as
>2 or 3 ohms..."
yep..
>That's why I wonder about the popularity of these 9-to-1 baluns.
generally a waste of money I think... Some bands they might
help, some might hurt... The reason I think it's a waste of time
is rarely are they actually needed to improve the s/n ratio.
>One of my antennas is a 20 meter end fed wire, and I tune it with an
>old Heathkit AC-1 antenna tuner, which is made especially for random
>length, end fed wires. A modern equivalent would be something like the
>MFJ-16010 random wire tuner, which at $49.95 doesn't cost much more
>than some of the 9-1 baluns I see advertised :-)
I've had one of those 16010's since about 1978. Still works, and I
usually use for a mobile impedance matcher. You can reverse the
leads if you want to match a low z load vs the normal high Z used
with most random wire tuners.
>It would require bringing the random wire into your residence, and
>then running a short length of coax from the tuner to the receiver. I
>understand some wouldn't like that because of in-house noise, but
>there are always trade-offs to anything.
Myself, giving that there is usually no increase in s/n ratio
when using a tuner to match a random wire, or other wire
antenna, I'd generally prefer a preselector over a tuner.
The tuner will help reduce out of band signals, but the
preselector will usually do a better job at that.
You can make a simple random wire tuner with a wound
coil that you can tap with a gator clip, and a variable cap.
The 16010 uses a wound tapped toroid inductor instead of the
coil, but otherwise is the same.
When listening on 160m with my IC 706mk2g, I sometimes
get AM-BC interference that puts images across the band.
We have a lot of strong MW stations in this town.
Using my MFJ-989c T match tuner will clean that stuff
right up. So even a tuner will act as a preselector of sorts.
MK
dxAce
nm...@wt.net wrote:
> >The
> >measured radiation resistance can be as high as 5000 ohms or as low as
> >2 or 3 ohms..."
>
> yep..
>
> >That's why I wonder about the popularity of these 9-to-1 baluns.
>
> generally a waste of money I think... Some bands they might
> help, some might hurt... The reason I think it's a waste of time
> is rarely are they actually needed to improve the s/n ratio.
Hardly a waste of money, they actually DO work.
Been using them here for a good number of years.
dxAce
Michigan
USA
David
wrote:
Wow. Steve and I agree on something. Call Kofi Annan.
dxAce
David wrote:
Why? You got some oil you'd like to trade for food?
dxAce
Michigan
USA
David
wrote:
>
>Why? You got some oil you'd like to trade for food?
>
I haven't paid too much attention to it, but I think the oil was never
meant to be traded directly for food. I think the name means that
Iraq was allowed to sell oil in order to be able to afford imported
edibles.
RHF
Michael Lawson
"dxAce" <dx...@milestones.com> wrote in message
news:43B45592...@milestones.com...
I put one together last year, and yes, I agree with
Ace. Of course, sealing the darn thing properly
to prevent leakage into the case is important too.
Had to go back a couple of times to reseal it to
make sure it works, but they actually do work.
--Mike L.
RHF
Inside view of the RF Systems Magnetic Longwire Balun ( MLB )
http://www.remeeus.nl/english/hamradio/mlb.htm
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/7245
RF Systems Magnetic Longwire Balun ( MLB )
http://www.thiecom.de/mlb.htm
http://www.universal-radio.com/catalog/sw_ant/1484.html
http://www.suertenich.com/html/radios/longwire_balun.html
http://www.universal-radio.com/catalog/sw_ant/4067chrt.html
http://www.universal-radio.com/catalog/sw_ant/1465.html
http://www.thiecom.de/mlb_1.jpg
images and Ideas - iane ~ RHF
dxAce
RHF wrote:
They're a funny bunch of folks. They threatened to sue me at one time.
dxAce
Michigan
USA
RHF
Here is one method of Sealing a Matching Transformer {Balun}
for the OutSide Weather in Text and Images - presented by RF Junkie
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/7246
Weather-Proofing QB Series Baluns
http://www.geocities.com/qrp_baluns/weatherizing.html
* Here is a simple method for weather-proofing the "QB" Series
and SWLZ Baluns.
* This is an inexpensive way to protect your Balun, if it should be
subjected out in the Weather for an extended period of time.
Read - RF Junkie 'introduces' new SWLZ Balun using "F" Connector
for use with Low Noise RG6 Quad-Shield Coax Cable
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/4245
http://groups.google.com/group/rec.radio.shortwave/msg/a9b90bced20caa9d
Read - LMZ-75 Shortwave Listener (SWL) Longwire {Random Wire}
Antenna Impedance Matcher
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/6165
http://groups.google.com/group/rec.radio.shortwave/msg/f577c0e9783e7421
FYI - RF Junkie's Contact Information :
Jason Erickson [KG7RO]
eMail: k...@juno.com
Erickson Engineering
PRODUCTS => http://www.geocities.com/qrp_baluns/product.html
PRICE => http://www.geocities.com/qrp_baluns/price.html
BUY => http://stores.ebay.com/ERICKSON-ENGINEERING
.
.
and now you know - iane ~ RHF
.
Shortwave Listener's (SWL) Antenna Group on YAHOO !
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/
RHF
At the Price Mark-Ups - I am surprised at a Chinese
Manufacture like Tecsun or Degen has not gotten into
building and offering a reverse-engineered-product
like the Systems Magnetic Longwire Balun ( MLB ) ? ? ?
http://www.universal-radio.com/catalog/sw_ant/1484.html
Also the RF Systems MLBA-MK1 or MLBA-MK2 Antennas
http://www.universal-radio.com/catalog/sw_ant/1465.html
Figure with the Chinese Manufacturing Cost being 1/10th
of the European's. And the Chinese made Items selling
on eBay for 1/3 to 1/2 the Current RF Systems USA Price.
jm2cw ~ RHF
David
David
David
wrote:
>For One and All,
I use this stuff. I add a wrap of Scotch 33+ to keep the sealant dust
free.
r2000...@hotmail.com
Michael Lawson wrote:
>
> I put one together last year, and yes, I agree with
> Ace. Of course, sealing the darn thing properly
> to prevent leakage into the case is important too.
> Had to go back a couple of times to reseal it to
> make sure it works, but they actually do work.
>
> --Mike L.
I have found that using the black plastic 35MM fil canisters
filled with silicon seal works very well. The Kodak ones last
much longer then the other I have checked. Don't use the clear,
or translucent ones as they will fail in a single season.
I us the plastic ones for mini DXpeditions.
If you are lucky enough to hae an aluminum 33MM cnaister they
work great! My dad was an advanced photographer so I have a
few of the aluminium and even fewer of the even older painted
steel units.
I have an aluminium unit that has been up for ~10 years with no sign
of failure.
Terry
clifto
> I haven't paid too much attention to it, but I think the oil was never
> meant to be traded directly for food. I think the name means that
> Iraq was allowed to sell oil in order to be able to afford imported
> edibles.
Actually, Iraq wasn't supposed to get any money out of it until after the
program ended. The UN was to get the money and use it to send food, medicine,
and supplies, and build schools, electrical power stations and the like.
Instead the money went to enrich Kofi and his kid and Saddam, and to buy
Iraq more embargoed armaments.
--
If John McCain gets the 2008 Republican Presidential nomination,
my vote for President will be a write-in for Jiang Zemin.
cuh...@webtv.net
extension line for an antenna for one of my old Shortwave radios.What I
did was connected the two wires (I didn't fool with the ground wire) of
the line together with a piece of wire and I draped the line around over
piles of my junk in my house,I ran the line from the radio by my couch
in my living room and through my dining room and through my kitchen and
on down the hall and back through the living to near my front door.It
worked pretty good too.
Not to be too off topic but, www.devilfinder.com TripSmarter.com
Bulletin Boards New Orleans Street Cars are Back
I was lurking in a New Orleans online chatroom a few afternoons ago.A
woman in New Orleans said her toofs are hurting her.I piped up and
said,Well,at least you have some toofs.
cuhulin
cuh...@webtv.net
with them for a while.Their oldest son is in the Mississippi Air Natinal
Guard.He is a Chief Flight Loader on the C-17 Aircraft.He recently got
back from Iraq.They were flying equipment and supplies from U.S.A.and
from Turkey to Iraq.
cuhulin