Best antenna (preferrably wire)
 

I have a few questions and I thought that this may be the group that could
help. I have a nice sized backyard and would like to construct an antenna
that would give me good performance on 80-10m bands.

The convenient dimensions would put a support (far end) at either 92 feet
from the back of the house (support exists that is about 15-20 feet up) or
120 feet from the back of the house (mast anchored to the other side of a
shed could easily be installed. Or a more inconvenient support could be
erected up to 300 feet out (no support buildings) at the absolute far end of
the property. The width of the property as seen looking out the back window
is about 65 feet (no supports existing on either side).

Special circumstances and constraints:

-- No tall trees on the property.

-- Attic shack (attic window is probably about 25 feet up). Need to keep to
the attic.

-- Cable run from back of house to operating position within the attic would
be approximately 25 feet

-- MUST eliminate RFI in the shack and house.

My current setup is an end-fed longwire that works well on all bands except
40m (rig shuts down as I am dipping the SWR to almost 1:1 ;-). I threw up
the wire as winter was upon me. I have been off the air for almost 10 years
and REALLY wanted to get on the air again.

While the longwire is performing quite well with the exception of 40m I am
getting a ton of RF in the shack and it is blanking out TVs and creating
loud humming in speakers with 100W from the XMTR. I realize that this is
most likely due to the fact that I have inefficient RF ground and I have cut
and run radial at 1/4 wave for each band and ran them under the eaves up
here in the attic. This has not solved the problem. I am friendly with all
of my neighbors and have visited them and did testing on the bands with them
on the phone. They are not experiencing any problems. My wife, while
understanding, would REALLY like the problem to go away ;-)

My main goal is to build an antenna that will solve the aforementioned RFI
problem and that will provide good performance given my constraints.

Any ideas would be GREATLY appreciated.

Many Thanks and 73,
Vaughn
N2BHA

On Sat, 03 Jan 2004 18:38:59 GMT, "Vaughn Combs"
wrote:

I have a few questions and I thought that this may be the group that could
help. I have a nice sized backyard and would like to construct an antenna
that would give me good performance on 80-10m bands.

The convenient dimensions would put a support (far end) at either 92 feet
from the back of the house (support exists that is about 15-20 feet up) or
120 feet from the back of the house (mast anchored to the other side of a
shed could easily be installed. Or a more inconvenient support could be
erected up to 300 feet out (no support buildings) at the absolute far end of
the property. The width of the property as seen looking out the back window
is about 65 feet (no supports existing on either side).

Special circumstances and constraints:

-- No tall trees on the property.

-- Attic shack (attic window is probably about 25 feet up). Need to keep to
the attic.

-- Cable run from back of house to operating position within the attic would
be approximately 25 feet

-- MUST eliminate RFI in the shack and house.

My current setup is an end-fed longwire that works well on all bands except
40m (rig shuts down as I am dipping the SWR to almost 1:1 ;-). I threw up
the wire as winter was upon me. I have been off the air for almost 10 years
and REALLY wanted to get on the air again.

While the longwire is performing quite well with the exception of 40m I am
getting a ton of RF in the shack and it is blanking out TVs and creating
loud humming in speakers with 100W from the XMTR. I realize that this is
most likely due to the fact that I have inefficient RF ground and I have cut
and run radial at 1/4 wave for each band and ran them under the eaves up
here in the attic. This has not solved the problem. I am friendly with all
of my neighbors and have visited them and did testing on the bands with them
on the phone. They are not experiencing any problems. My wife, while
understanding, would REALLY like the problem to go away ;-)

My main goal is to build an antenna that will solve the aforementioned RFI
problem and that will provide good performance given my constraints.

Any ideas would be GREATLY appreciated.

Many Thanks and 73,
Vaughn
N2BHA


Hi Vaughn,

Your first shot is probably your best shot. You should drop a line
from the near end antenna anchor point directly down to a ground and
rely on a tuner to make up the differences. From the anchor point
(where both wires are broke out) install a 1:1 Current Balun (Choke)
between these points and the transmission line back to your rig to
eliminate some of your noise into the house, and to get rid of the 40M
instability (a classic symptom of Common Mode whose cure is in the
Choke). The "ground" lead will radiate, but that is inconsequential.
You may also experience a ground loop with it in parallel to your
rig's source of ground.

This is the blind-side of many hams who forget that long ground wires
have impedance and thus become miserable grounds for RF. Unless you
work battery operation without a floating charger, you WILL have this
second path to ground (the 'trons will find their own way, even if it
isn't obvious to you). I always run battery with a float charger
through an 1:1 isolation transformer to kill Mains borne noise; and
whenever I experience ground loops, I simply disconnect the charger.

73's
Richard Clark, KB7QHC

Vaughn Combs wrote:
Any ideas would be GREATLY appreciated.

To effectively avoid RF in the shack, the differential currents need
to be balanced (equal in magnitude and 180 degrees out of phase). It
is extremely difficult to do that with an inv-L. I had good luck with
a dipole even though the shack was under one end of the dipole. I
brought the ladder-line off at right angles for about 50 ft then
routed ladder-line back to the shack from there so ladder-line
parallel to the antenna was always about 50 ft away from the antenna.
--
73, Cecil http://www.qsl.net/w5dxp



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I have a few questions and I thought that this may be the group that could
help. I have a nice sized backyard and would like to construct an antenna
that would give me good performance on 80-10m bands.

Well, you could build a full wave loop/delta loop...you'd need 3 good mounting
points up as far as you can get em..In my case I used trees in the
backyard..the height in my case was anywhere from 10 ft to about 30 ft...the
loop works great and will work everything from 10-80 with a tuner...the lowest
swr your likely to find is about 1.7:1..

The length to get it resonant at about the middle of 80 meters is aprox 250ft
using insulated wire, around 260ft using bare antenna wire..the equation is
1005/freq..but subtract about 5% if you use insulated wire..just works out that
way..you can feed the loop with plain ole coax like I did...good luck es 73's
de kb8viv.

Steve

Hi Richard,

If this helps both my XYL and I will be in your debt ;-)

So I should solder a shielded copper wire to the near end (aka the feed
point but on the other side of the insulator --- near the house), let it run
down the side of the house (about 22 to 25 feet down) and then to a ground
rod? Then connect both the wire from the point where the new ground wire
attaches and the wire (formerly the feedline) that connects to the "long"
wire to the balun. Then its on into the house and the tuner via RG-8.
Correct?

What do I connect to the ground lugs on the tuner and rig? The inefficient
RF ground wire that I have now? That wire currently goes to a ground strip
that has 1/4 wave length radials that were cut for each band running through
the attic and an additional wire that is attached to a pipe that I found in
the attic that is a plumbing drain pipe vent.

BTW, would there be any advantage to using other than 1:1 for the current
balun? Any recommendations for the balun? I have seen some that can be made
simply from coax.

I hope that I am not being a pain but this RFI prob is a bugger and it would
be REALLY nice to squash this one. It is bugging the XYL quite a bit and it
limits my operating time ;-)

Also, the ground loop that you are referring to would be current in the
shield (or in my case the outer skin of the copper wire ;-) coming through
the feed line and into the equipment. From there it is possibly getting into
electrical ground through the power supply?

Again, Many thanks for your help and 73,

Vaughn, N2BHA



"Richard Clark" wrote in message
...
On Sat, 03 Jan 2004 18:38:59 GMT, "Vaughn Combs"
wrote:

I have a few questions and I thought that this may be the group that
could
help. I have a nice sized backyard and would like to construct an antenna
that would give me good performance on 80-10m bands.

The convenient dimensions would put a support (far end) at either 92 feet
from the back of the house (support exists that is about 15-20 feet up)
or
120 feet from the back of the house (mast anchored to the other side of a
shed could easily be installed. Or a more inconvenient support could be
erected up to 300 feet out (no support buildings) at the absolute far end
of
the property. The width of the property as seen looking out the back
window
is about 65 feet (no supports existing on either side).

Special circumstances and constraints:

-- No tall trees on the property.

-- Attic shack (attic window is probably about 25 feet up). Need to keep
to
the attic.

-- Cable run from back of house to operating position within the attic
would
be approximately 25 feet

-- MUST eliminate RFI in the shack and house.

My current setup is an end-fed longwire that works well on all bands
except
40m (rig shuts down as I am dipping the SWR to almost 1:1 ;-). I threw
up
the wire as winter was upon me. I have been off the air for almost 10
years
and REALLY wanted to get on the air again.

While the longwire is performing quite well with the exception of 40m I
am
getting a ton of RF in the shack and it is blanking out TVs and creating
loud humming in speakers with 100W from the XMTR. I realize that this is
most likely due to the fact that I have inefficient RF ground and I have
cut
and run radial at 1/4 wave for each band and ran them under the eaves up
here in the attic. This has not solved the problem. I am friendly with
all
of my neighbors and have visited them and did testing on the bands with
them
on the phone. They are not experiencing any problems. My wife, while
understanding, would REALLY like the problem to go away ;-)

My main goal is to build an antenna that will solve the aforementioned
RFI
problem and that will provide good performance given my constraints.

Any ideas would be GREATLY appreciated.

Many Thanks and 73,
Vaughn
N2BHA


Hi Vaughn,

Your first shot is probably your best shot. You should drop a line
from the near end antenna anchor point directly down to a ground and
rely on a tuner to make up the differences. From the anchor point
(where both wires are broke out) install a 1:1 Current Balun (Choke)
between these points and the transmission line back to your rig to
eliminate some of your noise into the house, and to get rid of the 40M
instability (a classic symptom of Common Mode whose cure is in the
Choke). The "ground" lead will radiate, but that is inconsequential.
You may also experience a ground loop with it in parallel to your
rig's source of ground.

This is the blind-side of many hams who forget that long ground wires
have impedance and thus become miserable grounds for RF. Unless you
work battery operation without a floating charger, you WILL have this
second path to ground (the 'trons will find their own way, even if it
isn't obvious to you). I always run battery with a float charger
through an 1:1 isolation transformer to kill Mains borne noise; and
whenever I experience ground loops, I simply disconnect the charger.

73's
Richard Clark, KB7QHC

On Sat, 03 Jan 2004 22:11:39 GMT, "Vaughn Combs"
wrote:

Hi Richard,

If this helps both my XYL and I will be in your debt ;-)

It comes with the usual expectation of your first born....

So I should solder a shielded copper wire to the near end (aka the feed
point but on the other side of the insulator --- near the house), let it run
down the side of the house (about 22 to 25 feet down) and then to a ground
rod? Then connect both the wire from the point where the new ground wire
attaches and the wire (formerly the feedline) that connects to the "long"
wire to the balun. Then its on into the house and the tuner via RG-8.
Correct?

Yup. That is what I was describing, but it could work dangling (with
a sealed, insulated end that is mechanically tied down; however, this
is not anymore efficient as the floating wires along your rafters,
merely different).

View with fixed font:
BalUn longwire
rig --- tuner ant ---OOOOO-----------------------------
rig --- tuner gnd ---OOOOO-+
| |
| | drop
| |
----- -----
--- ---
- -

Ground loop issues arise due to there being two paths with a
significant distance (in wavelength) between them (from the +
down, through ground, and back up to the rig) and an impedance between
(the BalUn which serves this purpose by design). This usually comes
about when the ham shack is elevated, and still has some form of
ground return that is an appreciable distance (in wavelength,
basically more than 0.1 wavelength) from true ground.

The rig ground may be deliberate, or it may be passive through metal
connections and continuity with the power supply which in turn
inherits it from the wall socket. Even if there is no safety ground
from the wall socket, there is still a capacitive coupling in the
wiring to fulfill the mission (and 40/80M probably plays hell with the
VCR).

What do I connect to the ground lugs on the tuner and rig? The inefficient
RF ground wire that I have now? That wire currently goes to a ground strip
that has 1/4 wave length radials that were cut for each band running through
the attic and an additional wire that is attached to a pipe that I found in
the attic that is a plumbing drain pipe vent.

This may still be a viable option. Don't discard anything, simply
isolate one or all and experiment (it's the name of the game).


BTW, would there be any advantage to using other than 1:1 for the current
balun? Any recommendations for the balun? I have seen some that can be made
simply from coax.

Simple coax chokes work just as effectively. Half a dozen to eight
turns of six to eight inch turns will be adequate for 40-15M, you may
need to experiment with a few more turns outside of this. Current
BalUns are simply Ferrite donuts put over a 1 foot length of RG-52
coax (one or a couple dozen donuts). The same thing can be achieved
with a large torus with four or five turns of coax through the center
(if its big enough). This is square law time, so four turns equals 16
donuts. Stacking two large toroids with 3 turns each would substitute
(or maybe three with three turns).

Using ferrite makes for a smaller device that works over a larger span
of frequencies, but winding air wounds can be tested immediately at no
more cost than the cable already handy.

I hope that I am not being a pain but this RFI prob is a bugger and it would
be REALLY nice to squash this one. It is bugging the XYL quite a bit and it
limits my operating time ;-)

Also, the ground loop that you are referring to would be current in the
shield (or in my case the outer skin of the copper wire ;-) coming through
the feed line and into the equipment. From there it is possibly getting into
electrical ground through the power supply?

Again, Many thanks for your help and 73,

Vaughn, N2BHA

Hi Vaughn,

I've described the ground loop above. Isolating it means "busting"
ground somewhere. I use a battery. Voila! Opening any path does
just as well, but you have a dangling radiator somewhere (like the
drop). This may help, or it may change nothing. RFI problems are
unique to every situation and having your shack up high is the major
contributor, but to keep peace in the family try to limit RF exposure
to the end of the pipe (the purpose of the choke).

The choke inhibits RF from traveling back (conduction) into your shack
(but your rafter mounted "radials" contribute RF exposure through
radiation). You might try wrapping your power supply AC leads through
a ferrite (or use a split core). This is choking your rig from going
into the House AC. If you do this, take care to observe ALL
connections to the rig. Do you have a packet connection to the rig
from a computer? This is another path to ground, Choke it!!! Do you
have a modem on the computer? Ditto. Computer Display? Ditto. A
powered microphone? Ditto. The shack is a hydra of wires all heading
to ground eventually and all it takes is one - and sometimes it melts.

There are three forms of power transfer: Conduction, Radiation, and
Convection. Clearly convection is out as we are not heating soup.
Conduction comes through wire, and radiation through the air. Your
problems (as for most) usually comes by virtue of shared paths in the
AC distribution and this is a conduction issue. If you move your
rig's power supply to another wall socket ON A DIFFERENT BREAKER, you
might solve one problem (and discover a new one). Use an extension
cord (choke it) to experiment with this possibility. Having the
antenna feed point close to the house brings about the possibility of
radiation coupling. Move it (the choke point) away from the house.
Remember this is square law time too and with each doubling, you
quarter your exposure.

73's
Richard Clark, KB7QHC

Vaughn, N2BHA wrote:
"---I have cut and run radial at 1/4 wave for each band and run them
under the eaves up here in the attic."

Unless elevated radials are balanced, they radiate. One 1/4-wave wire
for each band is an antenna for each band radiating directly into your
house.

Best regards, Richard Harrison, KB5WZI

hi there..

think i will put my pennys worth in here...

do away with the long wire altogether..you will proberly never get rid of
the rf in shack etc..due to being too high above gnd..i know i have tried..i
live in an apartment (3rd floor)..no garden or land..i have tried end feed
long wire from balcony to lamp post etc..rfi to phones stereo etc..BAD

i tried all the tricks in the book no go...
SO.. i chatted my neighboors up and have been using successfully for 4 years
now a full sized 10m-80m diople (trapped with 40m trapps.)its slung up at 3
points in the shape of a triangle each courner on someone elses
apartment..the coax feed is rolled up 6 times 6inches dia just before diople
feed point..i have hung seperate dioples for 18mhz.28mz below main diople to
help on those bands ..
i have had NO tvi/stereo i/ phone i etc atall (touch wood)..i am using full
size diople but not out straight so you could too, espically as you have a
garden!!!
and have worked much dx all over the world with 100w ssb...

so if you give up with the long wire (as i did) try this..its cheap too..and
the antenna is in about every antenna handbook..)

simon g0zen
"Cecil Moore" wrote in message
...
Vaughn Combs wrote:
Any ideas would be GREATLY appreciated.

To effectively avoid RF in the shack, the differential currents need
to be balanced (equal in magnitude and 180 degrees out of phase). It
is extremely difficult to do that with an inv-L. I had good luck with
a dipole even though the shack was under one end of the dipole. I
brought the ladder-line off at right angles for about 50 ft then
routed ladder-line back to the shack from there so ladder-line
parallel to the antenna was always about 50 ft away from the antenna.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

Always begin with the most simple of antennas. Otherwise you'll have
nothing to make comparisons with. You will have no base or foundation
standard.

Spend a couple of hours stringing up a 150 feet inverted-L and use it on all
bands for a few weeks. That is if you can wrench youself away from it.
----
Reg, G4FGQ

Vaughn,

It's quite easy: your best bet is the maximum length of wire you can keep
in your backyard AND as high up in the air as you can afford (trees,
towers, chimneys etc.)

To prevent RFI and TVI, make your antenna symmetrical. Feed it with an
open line, and connect the open line with your TX with an appropriate
coupler (the ARRL Handbook is a good source for information).

Please note you do not need to use a thick gauge of copper wire. Even a
thin gauge of stainless steel wire will do.

You will be pleased very much by the results !!

73 de PA0ARY

On Sat, 03 Jan 2004 18:38:59 +0000, Vaughn Combs wrote:

I have a few questions and I thought that this may be the group that could
help. I have a nice sized backyard and would like to construct an antenna
that would give me good performance on 80-10m bands.

The convenient dimensions would put a support (far end) at either 92 feet
from the back of the house (support exists that is about 15-20 feet up) or
120 feet from the back of the house (mast anchored to the other side of a
shed could easily be installed. Or a more inconvenient support could be
erected up to 300 feet out (no support buildings) at the absolute far end of
the property. The width of the property as seen looking out the back window
is about 65 feet (no supports existing on either side).

Special circumstances and constraints:

-- No tall trees on the property.

-- Attic shack (attic window is probably about 25 feet up). Need to keep to
the attic.

-- Cable run from back of house to operating position within the attic would
be approximately 25 feet

-- MUST eliminate RFI in the shack and house.

My current setup is an end-fed longwire that works well on all bands except
40m (rig shuts down as I am dipping the SWR to almost 1:1 ;-). I threw up
the wire as winter was upon me. I have been off the air for almost 10 years
and REALLY wanted to get on the air again.

While the longwire is performing quite well with the exception of 40m I am
getting a ton of RF in the shack and it is blanking out TVs and creating
loud humming in speakers with 100W from the XMTR. I realize that this is
most likely due to the fact that I have inefficient RF ground and I have cut
and run radial at 1/4 wave for each band and ran them under the eaves up
here in the attic. This has not solved the problem. I am friendly with all
of my neighbors and have visited them and did testing on the bands with them
on the phone. They are not experiencing any problems. My wife, while
understanding, would REALLY like the problem to go away ;-)

My main goal is to build an antenna that will solve the aforementioned RFI
problem and that will provide good performance given my constraints.

Any ideas would be GREATLY appreciated.

Many Thanks and 73,
Vaughn
N2BHA