My outdoor longwire antenna works just about as well as I could imagine.
Very long wire, very high, attached to shielded 50ohm coax about 40 feet
from the house to avoid all the noise, and connected through a MLB. I get
amazing reception on all my radios.

So now I have a second "listening post" on another floor, and have decided
that I'll feed a high-impedance antenna to that spot. Some radios, mostly
my older ones, don't have a low-impedance input, just the normal
slotted-screw antenna wire hookup. This will give me an easy way to play
with these.

I might try a slinky outside, or maybe not. (Any real-world opinions on a
slinky vs. long wire?)

My real question is this: Can I use similar 50ohm shielded coax as my
feedline, to take advantage of the shielding and get the antenna away from
the house? I would of course not use the balun or even the connectors, just
connect the antenna to the center conductor, and strip away enough inside
the house to connect the center conductor directly to the radio. Will this
work? Is it a sound design?

Thanks,
Jeff

Thanks David, but the balun matches the high-impedance longwire to the
low-impedance antenna input. Now I'm connecting to a high-impedance input,
but want to achieve the same level of shielding.


"David" wrote in message
...
On Sun, 1 Oct 2006 09:14:51 -0400, "Unrevealed Source"
wrote:

My outdoor longwire antenna works just about as well as I could imagine.
Very long wire, very high, attached to shielded 50ohm coax about 40 feet
from the house to avoid all the noise, and connected through a MLB. I get
amazing reception on all my radios.

So now I have a second "listening post" on another floor, and have decided
that I'll feed a high-impedance antenna to that spot. Some radios, mostly
my older ones, don't have a low-impedance input, just the normal
slotted-screw antenna wire hookup. This will give me an easy way to play
with these.

I might try a slinky outside, or maybe not. (Any real-world opinions on a
slinky vs. long wire?)

My real question is this: Can I use similar 50ohm shielded coax as my
feedline, to take advantage of the shielding and get the antenna away from
the house? I would of course not use the balun or even the connectors,
just
connect the antenna to the center conductor, and strip away enough inside
the house to connect the center conductor directly to the radio. Will
this
work? Is it a sound design?

Thanks,
Jeff

Use the ''balun'' to match the wire to the transmission line. Connect
the center conductor of the transmission line to the ANT screw on the
receiver, and the shield to GND. Ground the mess according to local
codes.

David wrote:
On Sun, 1 Oct 2006 09:14:51 -0400, "Unrevealed Source"
wrote:

My outdoor longwire antenna works just about as well as I could imagine.
Very long wire, very high, attached to shielded 50ohm coax about 40 feet
from the house to avoid all the noise, and connected through a MLB. I get
amazing reception on all my radios.

So now I have a second "listening post" on another floor, and have decided
that I'll feed a high-impedance antenna to that spot. Some radios, mostly
my older ones, don't have a low-impedance input, just the normal
slotted-screw antenna wire hookup. This will give me an easy way to play
with these.

I might try a slinky outside, or maybe not. (Any real-world opinions on a
slinky vs. long wire?)

My real question is this: Can I use similar 50ohm shielded coax as my
feedline, to take advantage of the shielding and get the antenna away from
the house? I would of course not use the balun or even the connectors, just
connect the antenna to the center conductor, and strip away enough inside
the house to connect the center conductor directly to the radio. Will this
work? Is it a sound design?

Thanks,
Jeff

Use the ''balun'' to match the wire to the transmission line. Connect
the center conductor of the transmission line to the ANT screw on the
receiver, and the shield to GND. Ground the mess according to local
codes.

I solved my SWL antnenna noise problem by using 120 feet of 50 Ohm quad
shielded coax to a 30 foot vertical antenna in the back yard. I used a
Shortwave Antenna Longwire Transformer Balun - #LMZ-50 SWL Matcher,
which was made and sold by ERICKSON ENGINEERING. You must ground the
outside of the coax to the service ground. I also use a ground rod
with 6 gauge copper wire to the shack. My roof feed through
arrangement is shown at:
http://ph.groups.yahoo.com/group/Sho...os/browse/85e7
You should be able to get good results with just one of the baluns,
If you think you really want a High Z input to the radio, you could use
a second one of these transformers at the radio. The full description
of the balun is: ---------------
The purpose of this device is to match high impedance of the longwire
antenna to your low impedance receiver. Since a longwire antenna is
usually quite high in impedance (approx 400 to 700 ohms) you will have
considerable loss if you connect the wire directly to your low
impedance antenna terminals on your shortwave receiver. So by adding
this device at the end of your longwire you will increase your receive
signal strength a considerably amount on many frequencies across the HF
bands. By using coax for your feed you will also greatly reduce the
noises caused by TV's, computers, home lighting systems and other
electronics so that you can receive with much better clarity then with
a single wire through your window to the receiver. This device is also
shunt-fed so that static discharges are sent to the ground of the coax
rather than to your sensitive receiver front end. Some experimenting
with the length and height of your longwire may be needed to help your
reception even more. A length of 25 meters (approx 80ft) of wire is
recommended for best results, however if you have limited space to work
with a length of 30ft or more will give very good results This wire
does not have to be in a straight line to be effective as L or Z shapes
can work as well. The LMZ-50 is for use on radios with low-impedance
(50 ohm) antenna connection.

The LMZ-50 antenna match is designed for 50 ohm coax using PL-259
connectors on the coax. This is a special 10:1 Voltage Balun for
matching a longwire / random wire to 50 ohm coax down to your shortwave
receiver. The ground is carried down through the coax and then to the
radio. The radio receiver will then provide a ground to an outside
ground rod. An optional tuner / preselector can be placed between the
coax and the receiver.

Receive Frequency Range: 500KHz - 55MHz

THE LMZ-50 CAN BE USED ON LOW POWER TRANSMITTERS UP TO 10W (HF ONLY)

For information on WIRING and GROUNDING with the LMZ-50:
http://tinyurl.com/lnwcn



These impedance matching transformers are encased in a durable PVC
housing with heavy duty stainless steel connecting hardware for the
antenna terminal. This device is sealed from the elements and designed
for the weather. However it is always good practice to cover the
PL-259 connector with coax sealant tape to prevent water in your mating
connection.

------------

Noel N2FAV

The last sentence in one of the paragraphs says it all. The balun "is for
use on radios with low-impedance
(50 ohm) antenna connection."

The question is what if the radio doesn't have that, and you want to connect
the outside long-wire to the high-impedance input? It seems inefficient to
use two baluns, one on each end.


"NoelSpears" wrote in message
ps.com...

David wrote:
On Sun, 1 Oct 2006 09:14:51 -0400, "Unrevealed Source"
wrote:

My outdoor longwire antenna works just about as well as I could imagine.
Very long wire, very high, attached to shielded 50ohm coax about 40 feet
from the house to avoid all the noise, and connected through a MLB. I
get
amazing reception on all my radios.

So now I have a second "listening post" on another floor, and have
decided
that I'll feed a high-impedance antenna to that spot. Some radios,
mostly
my older ones, don't have a low-impedance input, just the normal
slotted-screw antenna wire hookup. This will give me an easy way to
play
with these.

I might try a slinky outside, or maybe not. (Any real-world opinions on
a
slinky vs. long wire?)

My real question is this: Can I use similar 50ohm shielded coax as my
feedline, to take advantage of the shielding and get the antenna away
from
the house? I would of course not use the balun or even the connectors,
just
connect the antenna to the center conductor, and strip away enough
inside
the house to connect the center conductor directly to the radio. Will
this
work? Is it a sound design?

Thanks,
Jeff

Use the ''balun'' to match the wire to the transmission line. Connect
the center conductor of the transmission line to the ANT screw on the
receiver, and the shield to GND. Ground the mess according to local
codes.

I solved my SWL antnenna noise problem by using 120 feet of 50 Ohm quad
shielded coax to a 30 foot vertical antenna in the back yard. I used a
Shortwave Antenna Longwire Transformer Balun - #LMZ-50 SWL Matcher,
which was made and sold by ERICKSON ENGINEERING. You must ground the
outside of the coax to the service ground. I also use a ground rod
with 6 gauge copper wire to the shack. My roof feed through
arrangement is shown at:
http://ph.groups.yahoo.com/group/Sho...os/browse/85e7
You should be able to get good results with just one of the baluns,
If you think you really want a High Z input to the radio, you could use
a second one of these transformers at the radio. The full description
of the balun is: ---------------
The purpose of this device is to match high impedance of the longwire
antenna to your low impedance receiver. Since a longwire antenna is
usually quite high in impedance (approx 400 to 700 ohms) you will have
considerable loss if you connect the wire directly to your low
impedance antenna terminals on your shortwave receiver. So by adding
this device at the end of your longwire you will increase your receive
signal strength a considerably amount on many frequencies across the HF
bands. By using coax for your feed you will also greatly reduce the
noises caused by TV's, computers, home lighting systems and other
electronics so that you can receive with much better clarity then with
a single wire through your window to the receiver. This device is also
shunt-fed so that static discharges are sent to the ground of the coax
rather than to your sensitive receiver front end. Some experimenting
with the length and height of your longwire may be needed to help your
reception even more. A length of 25 meters (approx 80ft) of wire is
recommended for best results, however if you have limited space to work
with a length of 30ft or more will give very good results This wire
does not have to be in a straight line to be effective as L or Z shapes
can work as well. The LMZ-50 is for use on radios with low-impedance
(50 ohm) antenna connection.

The LMZ-50 antenna match is designed for 50 ohm coax using PL-259
connectors on the coax. This is a special 10:1 Voltage Balun for
matching a longwire / random wire to 50 ohm coax down to your shortwave
receiver. The ground is carried down through the coax and then to the
radio. The radio receiver will then provide a ground to an outside
ground rod. An optional tuner / preselector can be placed between the
coax and the receiver.

Receive Frequency Range: 500KHz - 55MHz

THE LMZ-50 CAN BE USED ON LOW POWER TRANSMITTERS UP TO 10W (HF ONLY)

For information on WIRING and GROUNDING with the LMZ-50:
http://tinyurl.com/lnwcn



These impedance matching transformers are encased in a durable PVC
housing with heavy duty stainless steel connecting hardware for the
antenna terminal. This device is sealed from the elements and designed
for the weather. However it is always good practice to cover the
PL-259 connector with coax sealant tape to prevent water in your mating
connection.

------------

Noel N2FAV

On Sun, 1 Oct 2006 12:29:23 -0400, "Unrevealed Source"
wrote:

The last sentence in one of the paragraphs says it all. The balun "is for
use on radios with low-impedance
(50 ohm) antenna connection."

The question is what if the radio doesn't have that, and you want to connect
the outside long-wire to the high-impedance input? It seems inefficient to
use two baluns, one on each end.


You need to match the wire to the coax a lot more than you need to
match the coax to the radio.

The rule is Low Z can feed High Z, but High cannot feed LOW. Think of
pipes. Low Z = Narrow Pipe; High Z = Fat Pipe. Water can flow from
narrow pipe to fat pipe but not vice versa.

In article ,
"Unrevealed Source" wrote:

My outdoor longwire antenna works just about as well as I could imagine.
Very long wire, very high, attached to shielded 50ohm coax about 40 feet
from the house to avoid all the noise, and connected through a MLB. I get
amazing reception on all my radios.

So now I have a second "listening post" on another floor, and have decided
that I'll feed a high-impedance antenna to that spot. Some radios, mostly
my older ones, don't have a low-impedance input, just the normal
slotted-screw antenna wire hookup. This will give me an easy way to play
with these.

I might try a slinky outside, or maybe not. (Any real-world opinions on a
slinky vs. long wire?)

My real question is this: Can I use similar 50ohm shielded coax as my
feedline, to take advantage of the shielding and get the antenna away from
the house? I would of course not use the balun or even the connectors, just
connect the antenna to the center conductor, and strip away enough inside
the house to connect the center conductor directly to the radio. Will this
work? Is it a sound design?

There are three things to consider:
1. Antenna impedance.
2. Transmission line impedance. (example 50 ohm coax)
3. The receiver input impedance.

1, 2, and 3 all have to match.

Lets pretend the radio input is 500 ohms (to ground and the antenna is
also 500 ohms but you want to use 50 ohm coax between them for
receiving. You could use an UNUN on both ends (example the MLB) on the
antenna end and make a UNUN at the coax to receiver input. You would use
the same ratio as the MLB only use the windings in reverse so antenna
step down and at the other end step back up to the radio input.

--
Telamon
Ventura, California

- Unrevealed Source wrote:
- Thanks David, but the balun matches the high-impedance longwire
- to the low-impedance antenna input. Now I'm connecting to a high-
- impedance input, but want to achieve the same level of shielding.

US,

Using the Right Matching Transfomer at Both Ends of the Coax Cable :
[ When using the Radio / Receiver's HI-Z Terminals ]

1 - Long Wire Antenna-to-Coax use a 9:1 Step-Down-Transformer.

2 - Coax-to-Receiver-HI-Z-Terminals use a 1:4 Step-Up-Transformer.

yes it is that simple - iane ~ RHF

On Mon, 02 Oct 2006 00:35:05 GMT, m II wrote:

David wrote:

The rule is Low Z can feed High Z, but High cannot feed LOW. Think of
pipes. Low Z = Narrow Pipe; High Z = Fat Pipe. Water can flow from
narrow pipe to fat pipe but not vice versa.


David, I have to disagree here. A narrow pipe has a greater impedance to
flow than a fat one. Water can flow from either pipe to the other with
no difficulty but will change velocity. The rate of flow will stay the
same, with the velocity change compensating for the change in cross
sectional area.

Electricity doesn't give us the option of variable flow speed, so
something else has to give. Generally it is a varied total volume of
electrons delivered per unit of time, pressure(V) remaining the same.


NB. No viscous or any other forms of friction or drag coefficients were
hurt in the composition of this article.




mike
You're overthinking it. I was just trying to help the little feller
remember the rule.