Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
 

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.

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

Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
 

On 27 Dec 2005 20:33:15 -0800, "RHF"
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
.
.
. .
.

Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
 

On Wed, 28 Dec 2005 04:56:24 GMT, Bob Miller
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?

Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
 

On Wed, 28 Dec 2005 05:25:49 GMT, David wrote:

On Wed, 28 Dec 2005 04:56:24 GMT, Bob Miller
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?

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

Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
 

"Bob Miller" wrote in message ...
[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)

Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
 

On Wed, 28 Dec 2005 14:35:52 GMT, Bob Miller
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.

Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
 

Bob [K5QWG],

ABOUT - The "Low Noise" Antenna Design Concepts
that were popularized by John Doty :
http://groups.yahoo.com/group/Shortw...a/message/5178
http://groups.google.com/group/rec.r...38b087b5e89fee


Shortwave Listener (SWL) Longwire Antenna - by John Doty
? WHY Use a Fixed Matching Transformer ?
http://www.anarc.org/naswa/badx/ante..._longwire.html

hope this helps - iane ~ RHF
Shortwave Listener's (SWL) Antenna Group on YAHOO !
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/

Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
 

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.

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

Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use :Antenna Tuner? and/or Pre-Selector?
 

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

Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
 

On Thu, 29 Dec 2005 16:30:58 -0500, dxAce
wrote:



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
Wow. Steve and I agree on something. Call Kofi Annan.

Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use
 

David wrote:

On Thu, 29 Dec 2005 16:30:58 -0500, dxAce
wrote:



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
Wow. Steve and I agree on something. Call Kofi Annan.

Why? You got some oil you'd like to trade for food?

dxAce
Michigan
USA

Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
 

On Thu, 29 Dec 2005 19:03:41 -0500, dxAce
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.

Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
 

David - You are right ~ RHF

Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
 

"dxAce" wrote in message
...


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.

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.

Inside view of the RF Systems Magnetic Longwire Balun ( MLB )
 

On 30 Dec 2005 11:35:41 -0800, "RHF"
wrote:

For One and All,

Inside view of the RF Systems Magnetic Longwire Balun ( MLB )
http://www.remeeus.nl/english/hamradio/mlb.htm
http://groups.yahoo.com/group/Shortw...a/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/radio...ire_balun.html
http://www.universal-radio.com/catal.../4067chrt.html
http://www.universal-radio.com/catalog/sw_ant/1465.html
http://www.thiecom.de/mlb_1.jpg


images and Ideas - iane ~ RHF
.
.
. .
.
Now THAT is a rip-off.

Inside view of the RF Systems Magnetic Longwire Balun ( MLB )
 

On 30 Dec 2005 12:30:48 -0800, "RHF"
wrote:

DX Ace,

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
.
These guys charge fair prices.

http://www.geocities.com/qrp_baluns/product.html

Sealing a Matching Transformer {Balun} for the OutSide Weather
 

On 30 Dec 2005 11:59:23 -0800, "RHF"
wrote:

For One and All,
I use this stuff. I add a wrap of Scotch 33+ to keep the sealant dust
free.

http://www.coaxseal.com/How%20to%20Use%20Coax-Seal.htm

Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
 

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

Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
 

David wrote:
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.

Single Wire Antenna {Longwire / Random Wire Antenna} - What To...
 

A bunch of years ago,I used an old raggity fifty foot long electric
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

Single Wire Antenna {Longwire / Random Wire Antenna} - What To...
 

I went over to my old buddy and his wifes home this afternoon to visit
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