When people talk about the 'clearance' of an antenna, they seem to
mean how high the antenna is suspended above the earth and surrounding
objects. It also seems to be agreed that, at least with most types of
antennas, the more clearance you have, the better.

If I were going to put a random wire antenna on the roof of my five
story building, would the elevation resulting from its rooftop
location be a plus even it's only six or seven feet above the rooftop
itself (assuming there's not a lot of rfi up there from power lines,
the apartments below, etc.)?

Second question: I'm thinking the random wire should attach to a balun
which should then attach to a coax feedline. (My understanding is
that, if the wire isn't cut for a particular band, I'll need to use
either a balun or a tuner-- and it would be nice to avoid having to
fiddle with a tuner all the time.) But how does one determine what
sort of balun to use? For example, how does one decide whether to use
a 4:1 vs a 9:1 balun? Can anyone recommend a particular balun that
they've found to work well with a random wire antenna?

Thanks,

Steve

(Steve) wrote:

When people talk about the 'clearance' of an antenna, they seem to
mean how high the antenna is suspended above the earth and surrounding
objects. It also seems to be agreed that, at least with most types of
antennas, the more clearance you have, the better.

With many, yes. However there are certain antennas where the ground
(earth) plays a role in the reception.


If I were going to put a random wire antenna on the roof of my five
story building, would the elevation resulting from its rooftop
location be a plus even it's only six or seven feet above the rooftop
itself (assuming there's not a lot of rfi up there from power lines,
the apartments below, etc.)?

Good question. Don't know. It probably wouldn't make that big a
difference. People have used antennae laying on the ground with good
results.

With a random wire, the ground system is important, so that may be a
deciding factor. Can you lay a counterpoise or two on the roof?


Second question: I'm thinking the random wire should attach to a balun
which should then attach to a coax feedline. (My understanding is
that, if the wire isn't cut for a particular band, I'll need to use
either a balun or a tuner-- and it would be nice to avoid having to
fiddle with a tuner all the time.)

Okay, pedantic mode he What you'll be using is an un-un or a
matching transformer, not a "balun," despite the marketing hype
surrounding one particular company that loves the term.

For an end-fed wire, you actually DON'T want it to be resonant.

You also don't need a tuner -- see below.

But how does one determine what
sort of balun to use? For example, how does one decide whether to use
a 4:1 vs a 9:1 balun?

Experiment and try. I'd recommend the I.C.E. matching transformer
with multiple taps on it plus a ground lug -- the latter being crucial
for minimizing noise pickup.

The deal is that the impedence of the antenna at various non-resonant
frequencies is gonna be all over the place (with real and imaginary
components). What the transformer will do is give you a good
compromise choice that will minimize signal loss across your bands of
interest -- remember, your antenna is not resonant, nor should it be.

Can anyone recommend a particular balun that
they've found to work well with a random wire antenna?

I can't recommend I.C.E. products strongly enough. They are high
quality, have the right features, and do the job well. They don't try
to bull**** you with marketing either.

I.C.E. = Industrial Communication Engineers.

http://personal.isla.net/ice/
1-800-ICE-COMM

You'll probably have to call since their online catalog seems to be
incomplete. You are looking for a receive-only end-fed wire matching
transformer for HF.


Hope this helps


Thanks,

Steve

--
Eric F. Richards,
"Making me root for a sanctimonious statist blowhard like Kerry isn't
the worst thing Bush has done to the country. But it's the offense
that I take most personally."
-- http://www.reason.com/links/links071304.shtml

Eric F. Richards wrote:


I.C.E. = Industrial Communication Engineers.

http://personal.isla.net/ice/
1-800-ICE-COMM


More up-to-date-contact info:

http://www.arraysolutions.com/Products/ice/
(972) 203-2008


You want the I.C.E. 180A if your interests are only HF, or the I.C.E.
182A if your interests include MW. Same price.


--
Eric F. Richards,
"Nature abhors a vacuum tube." -- J. R. Pierce, Bell Labs, c. 1940

"Eric F. Richards" wrote
I.C.E. = Industrial Communication Engineers.

http://personal.isla.net/ice/
1-800-ICE-COMM


More up-to-date-contact info:

http://www.arraysolutions.com/Products/ice/
(972) 203-2008


You want the I.C.E. 180A if your interests are only HF, or the I.C.E.
182A if your interests include MW. Same price.

Concur that ICE equipment, incl that particular device works very well.
Don't forget to mention to folks that it is a *receive-only* device. Poster
in this thread was not clear what his intentions were, and some of your
comments sounded transmit-oriented (counterpoise, tuner, etc). The random
wire won't care much what's connected to it downstream besides a receiver,
if SWL is the focus. But the ICE matchbox does affect bands receivable by
shifting the impedance matching points. Finding the best fit on one band is
at the expense of some others, at least that has been my experience.

Jack Painter
Virginia Beach VA

Yes, I should have been clearer about this. At least right now, I'm
only looking to build a receive-only antenna.

As for the antenna ground, I'm still trying to work this out for
myself. I'm not sure a receive-only antenna requires much of a ground
in order to work well. However, with a length of wire on the roof I'll
obviously want a safety ground of some kind. There are a bunch of old
television antennas up there and I want to take a close look at them
to determine how they were grounded. My hope is that this will reveal
a convenient way to ground my antenna.

Thanks,

Steve

"Jack Painter" wrote in message news:Ngq2d.246250$Lj.27515@fed1read03...
"Eric F. Richards" wrote
I.C.E. = Industrial Communication Engineers.

http://personal.isla.net/ice/
1-800-ICE-COMM


More up-to-date-contact info:

http://www.arraysolutions.com/Products/ice/
(972) 203-2008


You want the I.C.E. 180A if your interests are only HF, or the I.C.E.
182A if your interests include MW. Same price.

Concur that ICE equipment, incl that particular device works very well.
Don't forget to mention to folks that it is a *receive-only* device. Poster
in this thread was not clear what his intentions were, and some of your
comments sounded transmit-oriented (counterpoise, tuner, etc). The random
wire won't care much what's connected to it downstream besides a receiver,
if SWL is the focus. But the ICE matchbox does affect bands receivable by
shifting the impedance matching points. Finding the best fit on one band is
at the expense of some others, at least that has been my experience.

Jack Painter
Virginia Beach VA

"Steve" wrote in message
om...
Yes, I should have been clearer about this. At least right now, I'm
only looking to build a receive-only antenna.

As for the antenna ground, I'm still trying to work this out for
myself. I'm not sure a receive-only antenna requires much of a ground
in order to work well. However, with a length of wire on the roof I'll
obviously want a safety ground of some kind. There are a bunch of old
television antennas up there and I want to take a close look at them
to determine how they were grounded. My hope is that this will reveal
a convenient way to ground my antenna.

Thanks,

Steve

Steve, if you affix the rooftop wire antenna to a Balun, which coax will
feed from your shack, a rooftop ground from exposed structural steel of the
building is possible. Inside an apartment, there is no ground available
other than the AC ground, which you may *never* connect an antenna to
directly. Bad enough that it will be indirectly connected via your radio
case, in the event of a lightning strike on the building roof.

So if you live in an area exposed to lightning, disconnecting an apartment
rooftop antenna at the roof is the only 100% safe method. Not that yourself
of hundreds of others might abide by that advice, but it is valid anyway.
You could install a lightning arrestor at the rooftop if you expose a good
ground up there. That would divert most of the energy away from your
feedline from a rooftop strike.

Jack


"Jack Painter" wrote in message
news:Ngq2d.246250$Lj.27515@fed1read03...
"Eric F. Richards" wrote
I.C.E. = Industrial Communication Engineers.

http://personal.isla.net/ice/
1-800-ICE-COMM


More up-to-date-contact info:

http://www.arraysolutions.com/Products/ice/
(972) 203-2008


You want the I.C.E. 180A if your interests are only HF, or the I.C.E.
182A if your interests include MW. Same price.

Concur that ICE equipment, incl that particular device works very well.
Don't forget to mention to folks that it is a *receive-only* device.
Poster
in this thread was not clear what his intentions were, and some of your
comments sounded transmit-oriented (counterpoise, tuner, etc). The
random
wire won't care much what's connected to it downstream besides a
receiver,
if SWL is the focus. But the ICE matchbox does affect bands receivable
by
shifting the impedance matching points. Finding the best fit on one band
is
at the expense of some others, at least that has been my experience.

Jack Painter
Virginia Beach VA

STEVE,

The Random Wire Antenna using a Magnetic Longwire Balun
(MLB) a 9:1 Un-Un "Matching Transformer" and Coax Cable
Feed-in-Line on the Roof will work OK.

Here are a few ready-made 9:1 MLBs:
- Palomar Magnetic Longwire Balun
http://www.palomar-engineers.com/MLB-1/mlb-1.html
- RF-Systems Magnetischer Langdraht Balun (MLB)
http://www.thiecom.de/mlb.htm
http://www.universal-radio.com/catalog/antsup/1484.html
- Universal Magnetic Balun UMB (9:1) by Wellbrook
http://www.wellbrook.uk.com/UMB.html
- WinRadio Long Wire Adapter (BNC Connector)
http://www.winradio.com/home/lwa.htm
- ICE-180A/182A Matching Transformers for Random/Longwire/Beverage
http://www.arraysolutions.com/Products/ice/reconly.html#Beverage%20Matching
http://www.arraysolutions.com/Products/ice/1.html
Here is some reading on the "Magnetic Longwire Balun"
- 'Not Really a Balun' by John Doty
http://www.hard-core-dx.com/nordicdx...d/magbal2.html


Here are a few things to consider before you start building:
- First take a 'portable' SW Radio and Check around the
Top of the Roof for any 'noise' generating sources. Place
your Antenna away from these 'noisy' areas.
- Try to locate a good Grounding Point on the Roof to
use as your Antenna's Ground. Must large/tall buildings
with Flat Roofs have some metal object/pipe/panel that
is a good ground.
- In general buildings have an RFI/EMF "Noise" Envelop
that can extend for several feet from the building. So
your idea of having the Wire Antenna Element above the
Top of the Roof is good. Do It !

The SHAPE of your Antenna:
- Run the Wire Antenna Element near the center of the
Roof so it can not be seen from the street.
- Run the Wire Antenna Element along the Side of the
Roof so that it is out of the way. This can be End-Fed
or Off-Center-Fed like a Windom Antenna.
- You may wish/need to run your Wire Antenna Element
along one side of the Roof and then turn a Corner and
along the another side of the Roof to make it longer.
- You can also start at a corner and use a single
Antenna Wire Element that runs out along two sides of
the Roof at a 90 Degree angle. These two legs do not
have to be the same length and are like a bent Windom
Antenna.

What To Do - When You Start Building:
- Plan, Located, Meassure and Draw-Out your Antenna,
Ground and Coax Feed-in-Line System.
- Establish the Antenna, Ground and Coax "Junction Point".
- Establish your Roof Top "Grounding Point" and Ground Wire.
- Establish your Antenna Supports. Consider using two
or more pieces of 1.5" x 10 Ft PVC Pipe as 'supports'
for your Wire Antenna Element and Rig the wire between
them.
- Route your Coax Cable from your Radio Shack to the
Roof and over-to the MLB Location that your have
established. This is the Junction of the Coax, Ground
Wire and Wire Antenna Element.
- Mount your MLB at the Junction Point usually about
One Foot above the Roof's Surface.
- Connect your Ground Wire to the MLB.
- Connect Your Coax Cable to the MLB.
- Route your Wire Antenna element and Connect it to the MLB.
Go down to your RadioShack and Connect the Coax Cable to
your Radio.
..
..
REMEMBER: "The AM/MW and Shortwave Antenna is 55.5% . . .
of the Radio/Receiver and Antenna/Ground Reception Equation"
http://groups.yahoo.com/group/Shortw...na/message/288
A Shortwave Antenna is "Equally" Important for Good Reception [.]
..
..
iane ~ RHF
..
Some Say: On A Clear Day You Can See Forever.
http://groups.yahoo.com/group/Shortw...na/message/502
I BELIEVE: On A Clear Night . . .
You Can Hear Forever and Beyond - The Beyond !
..
..
= = = *m (Steve) wrote in message
= = = . com...

When people talk about the 'clearance' of an antenna,
they seem to mean how high the antenna is suspended above
the earth and surrounding objects. It also seems to be
agreed that, at least with most types of antennas, the more
clearance you have, the better.

If I were going to put a random wire antenna on the roof
of my five story building, would the elevation resulting
from its rooftop location be a plus even it's only six
or seven feet above the rooftop itself (assuming there's
not a lot of rfi up there from power lines, the apartments
below, etc.)?

Second question: I'm thinking the random wire should
attach to a balun which should then attach to a coax
feedline. (My understanding is that, if the wire isn't
cut for a particular band, I'll need to use either a
balun or a tuner-- and it would be nice to avoid having
to fiddle with a tuner all the time.) But how does one
determine what sort of balun to use? For example, how
does one decide whether to use a 4:1 vs a 9:1 balun?
Can anyone recommend a particular balun that they've
found to work well with a random wire antenna?

Thanks, Steve
..

FO&A,

WAS: Two questions about random wire antennas

Two Shortwave Listener (SWL) 10:1 Baluns for Random Wire Antennas
http://groups.yahoo.com/group/Shortw...a/message/1523

These are being offered by eBay Seller "RF Junkie"
http://members.ebay.com/ws2/eBayISAP...serid=rfjunkie
http://feedback.ebay.com/ws/eBayISAP...serid=rfjunkie

Type # SWL-1 : Shortwave Listener 10:1 "MLB" features a SO-239
Connector with a connection for the Wire Antenna Element.

Type # SWL-1G : Shortwave Listener 10:1 "MLB" features a SO-239
Connector with connections for both an Wire Antenna Element and
a Ground Wire.

NOTE: Designed and Made in the USofA by Erickson Engineering.

iane ~ RHF
..
..
= = = (RHF) wrote in message
= = = . com...
STEVE,

The Random Wire Antenna using a Magnetic Longwire Balun
(MLB) a 9:1 Un-Un "Matching Transformer" and Coax Cable
Feed-in-Line on the Roof will work OK.

Here are a few ready-made 9:1 MLBs:
- Palomar Magnetic Longwire Balun
http://www.palomar-engineers.com/MLB-1/mlb-1.html
- RF-Systems Magnetischer Langdraht Balun (MLB)
http://www.thiecom.de/mlb.htm
http://www.universal-radio.com/catalog/antsup/1484.html
- Universal Magnetic Balun UMB (9:1) by Wellbrook
http://www.wellbrook.uk.com/UMB.html
- WinRadio Long Wire Adapter (BNC Connector)
http://www.winradio.com/home/lwa.htm
- ICE-180A/182A Matching Transformers for Random/Longwire/Beverage
http://www.arraysolutions.com/Products/ice/reconly.html#Beverage%20Matching
http://www.arraysolutions.com/Products/ice/1.html
Here is some reading on the "Magnetic Longwire Balun"
- 'Not Really a Balun' by John Doty
http://www.hard-core-dx.com/nordicdx...d/magbal2.html


Here are a few things to consider before you start building:
- First take a 'portable' SW Radio and Check around the
Top of the Roof for any 'noise' generating sources. Place
your Antenna away from these 'noisy' areas.
- Try to locate a good Grounding Point on the Roof to
use as your Antenna's Ground. Must large/tall buildings
with Flat Roofs have some metal object/pipe/panel that
is a good ground.
- In general buildings have an RFI/EMF "Noise" Envelop
that can extend for several feet from the building. So
your idea of having the Wire Antenna Element above the
Top of the Roof is good. Do It !

The SHAPE of your Antenna:
- Run the Wire Antenna Element near the center of the
Roof so it can not be seen from the street.
- Run the Wire Antenna Element along the Side of the
Roof so that it is out of the way. This can be End-Fed
or Off-Center-Fed like a Windom Antenna.
- You may wish/need to run your Wire Antenna Element
along one side of the Roof and then turn a Corner and
along the another side of the Roof to make it longer.
- You can also start at a corner and use a single
Antenna Wire Element that runs out along two sides of
the Roof at a 90 Degree angle. These two legs do not
have to be the same length and are like a bent Windom
Antenna.

What To Do - When You Start Building:
- Plan, Located, Meassure and Draw-Out your Antenna,
Ground and Coax Feed-in-Line System.
- Establish the Antenna, Ground and Coax "Junction Point".
- Establish your Roof Top "Grounding Point" and Ground Wire.
- Establish your Antenna Supports. Consider using two
or more pieces of 1.5" x 10 Ft PVC Pipe as 'supports'
for your Wire Antenna Element and Rig the wire between
them.
- Route your Coax Cable from your Radio Shack to the
Roof and over-to the MLB Location that your have
established. This is the Junction of the Coax, Ground
Wire and Wire Antenna Element.
- Mount your MLB at the Junction Point usually about
One Foot above the Roof's Surface.
- Connect your Ground Wire to the MLB.
- Connect Your Coax Cable to the MLB.
- Route your Wire Antenna element and Connect it to the MLB.
Go down to your RadioShack and Connect the Coax Cable to
your Radio.
.
.
REMEMBER: "The AM/MW and Shortwave Antenna is 55.5% . . .
of the Radio/Receiver and Antenna/Ground Reception Equation"
http://groups.yahoo.com/group/Shortw...na/message/288
A Shortwave Antenna is "Equally" Important for Good Reception [.]
.
.
iane ~ RHF
.
Some Say: On A Clear Day You Can See Forever.
http://groups.yahoo.com/group/Shortw...na/message/502
I BELIEVE: On A Clear Night . . .
You Can Hear Forever and Beyond - The Beyond !
.
.
= = = *m (Steve) wrote in message
= = = . com...

When people talk about the 'clearance' of an antenna,
they seem to mean how high the antenna is suspended above
the earth and surrounding objects. It also seems to be
agreed that, at least with most types of antennas, the more
clearance you have, the better.

If I were going to put a random wire antenna on the roof
of my five story building, would the elevation resulting
from its rooftop location be a plus even it's only six
or seven feet above the rooftop itself (assuming there's
not a lot of rfi up there from power lines, the apartments
below, etc.)?

Second question: I'm thinking the random wire should
attach to a balun which should then attach to a coax
feedline. (My understanding is that, if the wire isn't
cut for a particular band, I'll need to use either a
balun or a tuner-- and it would be nice to avoid having
to fiddle with a tuner all the time.) But how does one
determine what sort of balun to use? For example, how
does one decide whether to use a 4:1 vs a 9:1 balun?
Can anyone recommend a particular balun that they've
found to work well with a random wire antenna?

Thanks, Steve
.