Between a balanced line and unbalanced line in a shortwave receiver.

My antenna connects via alligator clips to the center conductor of a piece
of coax that connects to the receiver, radio shack dx 394.

The antenna works fairly well, given that I can connect what I want.
However, some times the static from the power lines and flourescent street
lights is really nasty, and I think I have read that an unbalanced line can
be rid of most intereference if it s balanced, but not being an amateur
radio operator, I am at a loss to undesrstand the difference between
balanced and unbalanced lines and this place seems to be one where I can ask
the question s. THANKS.

Okees . I tried to get some of that from the local tv repair shop & they
were out, so I got some coax.
How 'bout I connect one line to the sheilding on the coax, and one line to
the center conductor of the coax - is that considered balanced, or do i need
something between the receiver and the antenna line to create a balanced
connection ?

I hope you don't mind my asking questions about these fundamentals. If there
is a website to explain in simple terms, taht would save you the effort of
typing s. I DO appreciate the response.


"N8KDV" wrote in message
...


Warpcore wrote:

Between a balanced line and unbalanced line in a shortwave receiver.

Coaxial cable is unbalanced line. Balanced line is two equal conductors
spaced a
certain distance apart, like 300 ohm tv line.



My antenna connects via alligator clips to the center conductor of a
piece
of coax that connects to the receiver, radio shack dx 394.

The antenna works fairly well, given that I can connect what I want.
However, some times the static from the power lines and flourescent
street
lights is really nasty, and I think I have read that an unbalanced line
can
be rid of most intereference if it s balanced, but not being an amateur
radio operator, I am at a loss to undesrstand the difference between
balanced and unbalanced lines and this place seems to be one where I can
ask
the question s. THANKS.

Behold, Warpcore flashed in code from a keyed 4-1000A filament:

How 'bout I connect one line to the sheilding on the coax, and one line
to the center conductor of the coax - is that considered balanced, or do
i need something between the receiver and the antenna line to create a
balanced connection ?

Nope, not balanced. You should use a proper balanced line/antenna for best
results. You can use a BALUN between the coax and balanced inputs of your
RX.

TV types are 4:1 and the quality types can be used down to 5 MHz, with the
typical RS things good down to 15 MHz.

A 1:1 balun is probably your best option. You can wind your own (se ARRL
Radio Amateur's Handbooks) or purchase one called a "W2AU" balun, but
they're big. Only about $20 though. They are good from 160 to 6M.

I hope you don't mind my asking questions about these fundamentals. If
there is a website to explain in simple terms, taht would save you the
effort of typing s. I DO appreciate the response.

Typical balanced antennas are the dipole (folded full-wave [300 ohm] and
1/2 wave [72 ohm]), quad, delta and other loops. Unbalanced types are like
end-fed anything (longwires), J-poles, 1/4 wave verticals, etc.

An antenna will give proper performance if it's tuned to the lowest
frequency you expect to receive. For a 1/2 wave antenna, like a dipole,
the length should be:

Lmetres=150/fMHz

If you have limited property, you can helically wind it on a form.

For unbalanced antennas, a good ground is neccessary. Cold water pipes
are OK, but a counterpoise is better.

Balanced antennas are relatively independent of a ground, but the RX
equipment should be grounded for reduced noise and safety.

Hope this helps.

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
----------------------------------------
| GeeK Zone * scripts * articles * forum |
| http://geek.scorpiorising.ca |
----------------------------------------

Yep, it does. I have a ground connected to a 6 ft piece of rebar pounded
into the earth, the sheilding of the coax is connected to ground and so is
the receiver.

"Gregg" wrote in message
. ..
Behold, Warpcore flashed in code from a keyed 4-1000A filament:

How 'bout I connect one line to the sheilding on the coax, and one line
to the center conductor of the coax - is that considered balanced, or do
i need something between the receiver and the antenna line to create a
balanced connection ?

Nope, not balanced. You should use a proper balanced line/antenna for best
results. You can use a BALUN between the coax and balanced inputs of your
RX.

TV types are 4:1 and the quality types can be used down to 5 MHz, with the
typical RS things good down to 15 MHz.

A 1:1 balun is probably your best option. You can wind your own (se ARRL
Radio Amateur's Handbooks) or purchase one called a "W2AU" balun, but
they're big. Only about $20 though. They are good from 160 to 6M.

I hope you don't mind my asking questions about these fundamentals. If
there is a website to explain in simple terms, taht would save you the
effort of typing s. I DO appreciate the response.

Typical balanced antennas are the dipole (folded full-wave [300 ohm] and
1/2 wave [72 ohm]), quad, delta and other loops. Unbalanced types are like
end-fed anything (longwires), J-poles, 1/4 wave verticals, etc.

An antenna will give proper performance if it's tuned to the lowest
frequency you expect to receive. For a 1/2 wave antenna, like a dipole,
the length should be:

Lmetres=150/fMHz

If you have limited property, you can helically wind it on a form.

For unbalanced antennas, a good ground is neccessary. Cold water pipes
are OK, but a counterpoise is better.

Balanced antennas are relatively independent of a ground, but the RX
equipment should be grounded for reduced noise and safety.

Hope this helps.

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
----------------------------------------
| GeeK Zone * scripts * articles * forum |
| http://geek.scorpiorising.ca |
----------------------------------------

My thanks to you all

Does MFJ make anything that will balance the line and tune without
amplifying the signal ? I've had an active antenna in the past but was very
disappointed with results - so I really don't want amplification.

"Robert Jeffares" wrote in message
...
In a balanced line you have two wires running in paralell between [in your
case] the receiver and the antenna. Depending on the size of the wires and
the distance apart you have a nominal impedance of 300 ohms or 600 ohms
which is fine for the input to the radio, but not so hot when you are
trying
to match into a centre fed dipole which is about 75 ohms.

There are ways of matching into a dipole from balanced line. The ARRL
antenna handbook is a great place to start learning about this sort of
thing. Your local library will have a copy.

The big advantage of balanced line is low loss. You can run it a long way
and have relatively low loss. A balanced line is not interference free.
It
should be less interference prone, but proximity to metal pipes or metal
in
walls can affect the "balance". Running balanced lines "on the twist" can
reduce these external effects.

It is called "balanced" because the same signal runs in both conductors
equal and opposite.

In some cases balanced line is used in an unbalanced configuration. Don't
get hung up on it.

Co-ax is unbalanced because the signal is conducted down the central
wire,
and the shield is connected to earth, and surrounds the centre core
supposedly stopping any radiation. Well that's the theory!

You can run 50 - 75 ohm coax from the centre of a dipole antenna to the
aerial input of your receiver but the further you have to go the more
signal
you lose. Purists use a balun at the dipole feed point because the dipole
antenna is a balanced device and the co-ax is unbalanced [ bal - un ] .

Coax is good because you can run it almost anywhere without having to
worry
about what it is next to as the earth shield surrounds the signal wire
[remember that's the theory]. Good co-ax costs. The stuff they sell at
Radio
& TV stores is rubbish. Pay the extra $ and get RG 58 or something as good
from a reputable supplier.

To get the best result from any antenna you need a GOOD EARTH. Now
depending
where you live this is easy. Bury a metre of copper pipe in the ground and
connect a copper wire to the pipe scraping the oxide off and making some
kind of soldered connection or using a brass fitting made for the job and
running the earth line in to the radio. A good earth connection will
eliminate a lot of noise. the reasons are too complex to deal with here.
The mains earth in your house is NOT good enough if you actually have one.
You need a Radio Earth. if you live on level 10 of an apartment complex
getting a decent earth may be harder to achieve. Water pipe is good, if
there are no plastic sections.

In any location the property you have access to determines how big an
antenna you can put up. Get the wire high and clear. If you can arrange a
centre fed dipole all the better, but end fed is ok for Rx. Coax is fine
in
most applications unless you have a really low signal from the station you
want to listen to. But spend time getting a good earth connection. When
you
have noise from flouro's and computers try hooking a good earth connection
onto the radio.

If you really want to get the best match try and find an antenna tuner at
an
amateur supply store, or hang around amateur radio junk sales. You will be
surprised how much of a difference a simple tuner can make. You can make
something that works from junk parts.

Happy listening

I have read that an unbalanced line can
be rid of most intereference if it s balanced, but not being an amateur
radio operator, I am at a loss to undesrstand the difference between
balanced and unbalanced lines

A lot of hams don't know the difference either!

Robert

Gregg wrote in message ...
Behold, Warpcore flashed in code from a keyed 4-1000A filament:

How 'bout I connect one line to the sheilding on the coax, and one line
to the center conductor of the coax - is that considered balanced, or do
i need something between the receiver and the antenna line to create a
balanced connection ?

Nope, not balanced. You should use a proper balanced line/antenna for best
results. You can use a BALUN between the coax and balanced inputs of your
RX.

TV types are 4:1 and the quality types can be used down to 5 MHz, with the
typical RS things good down to 15 MHz.

A 1:1 balun is probably your best option. You can wind your own (se ARRL
Radio Amateur's Handbooks) or purchase one called a "W2AU" balun, but
they're big. Only about $20 though. They are good from 160 to 6M.

I hope you don't mind my asking questions about these fundamentals. If
there is a website to explain in simple terms, taht would save you the
effort of typing s. I DO appreciate the response.


Typical balanced antennas are the dipole (folded full-wave [300 ohm] and
1/2 wave [72 ohm]), quad, delta and other loops.
An antenna will give proper performance if it's tuned to the lowest
frequency you expect to receive. For a 1/2 wave antenna, like a dipole,
the length should be:
Lmetres=150/fMHz
Balanced antennas are relatively independent of a ground, but the RX
equipment should be grounded for reduced noise and safety.

IIRC: Generally these types of 'free standing' ~ 'up in the air'
antennas are required to be elevated high enough for the designed
frequency to reduce or elimated the ground effect to achieve the
designed antenna reception pattern.
Properly Constructed + Positioned + Elevated = Antennas Independent
from Ground


Unbalanced types are like
end-fed anything (longwires), J-poles, 1/4 wave verticals, etc.
For unbalanced antennas, a good ground is neccessary. Cold water pipes
are OK, but a counterpoise is better.

The Ground/Counterpoise is 'part' of the antenna (1/4, 1/2 or full
wavelength reflector).

iane ~ RHF




If you have limited property, you can helically wind it on a form.



Hope this helps.

"Warpcore" wrote in message rthlink.net...
Between a balanced line and unbalanced line in a shortwave receiver.

My antenna connects via alligator clips to the center conductor of a piece
of coax that connects to the receiver, radio shack dx 394.

The antenna works fairly well, given that I can connect what I want.
However, some times the static from the power lines and flourescent street
lights is really nasty, and I think I have read that an unbalanced line can
be rid of most intereference if it s balanced, but not being an amateur
radio operator, I am at a loss to undesrstand the difference between
balanced and unbalanced lines and this place seems to be one where I can ask
the question s. THANKS.

If you're not yet a member, you're invited to join the 445 member
special interest group for the DX-394 at
http://groups.yahoo.com/group/RADIOSHACKDX394/.

Tom

Many thanks for the invite, Tom, but I will refrain. Everytime I join a
yahoo group I am inundated with some really nasty spam S.

"tom Holden" wrote in message
m...
"Warpcore" wrote in message
rthlink.net...
Between a balanced line and unbalanced line in a shortwave receiver.

My antenna connects via alligator clips to the center conductor of a
piece
of coax that connects to the receiver, radio shack dx 394.

The antenna works fairly well, given that I can connect what I want.
However, some times the static from the power lines and flourescent
street
lights is really nasty, and I think I have read that an unbalanced line
can
be rid of most intereference if it s balanced, but not being an amateur
radio operator, I am at a loss to undesrstand the difference between
balanced and unbalanced lines and this place seems to be one where I can
ask
the question s. THANKS.

If you're not yet a member, you're invited to join the 445 member
special interest group for the DX-394 at
http://groups.yahoo.com/group/RADIOSHACKDX394/.

Tom

"Warpcore" wrote in message rthlink.net...
Many thanks for the invite, Tom, but I will refrain. Everytime I join a
yahoo group I am inundated with some really nasty spam S.

Anyone can view, so have a look at the message archive. Only members
can post and memberships are moderated so spam in the group is minimal
and promptly dealt with by deleting the offending membership and
messages. It's a much more focussed and polite community than will be
found in many unmoderated newsgroups. I can't speak for what Yahoo
does with the member lists.

"tom Holden" wrote in message
[snip]
If you're not yet a member, you're invited to join the 445 member
special interest group for the DX-394 at
http://groups.yahoo.com/group/RADIOSHACKDX394/.