Shortwave random-wire antenna question

[CW]

The bead on a wire idea works. It has been used frequently in crystal
radios.

 

[CW]

Good advice. No need to over design something if your not sure it will work.

 

[Rich Grise]

The antenna does indeed seem to be working great, and the radio is not
operating too shabily either as it is only the "background noise" I am
trying to reduce. I hooked a 100 mH RF choke up to it with good results,
and am planning on adding another one or two similar devices in an effort to
cut down on higher frequency interference. Question: how would I ground
this antenna?

Uh, you don't ground the antenna. You ground ground. The ground is like
a "return" path for the current induced in the antenna by the radio wave.

I have a grounding rod right outside the window, but don't
know what to hook it too. The negative battery terminal?

Probably. Any handy chassis ground will be fine.

This radio does
have an external antenna input, but that has a plastic ring around the
outside. Open to suggestions.

The radio might be grounded through the power cord, if it's a 3-prong.
Otherwise, just a wire from the radio's chassis to the ground rod, or
even to one of the mounting screws of a grounded outlet.

And thanks for the input RE purchasing a
new/used tuner.

dave

As you seem to have mentioned, you have lots & lots of signal
strenth, so you actually might want to make your antenna even _less_
sensitive. What it sounds like you're looking for is selectivity,
and you do that with tuned circuits. Or you did back when I was
learning this stuff. ;-)

Hope This Helps!
Rich

 

[Dave]

effort

Uh, you don't ground the antenna. You ground ground. The ground is like
a "return" path for the current induced in the antenna by the radio wave.


Probably. Any handy chassis ground will be fine.


The radio might be grounded through the power cord, if it's a 3-prong.
Otherwise, just a wire from the radio's chassis to the ground rod, or
even to one of the mounting screws of a grounded outlet.


As you seem to have mentioned, you have lots & lots of signal
strenth, so you actually might want to make your antenna even _less_
sensitive. What it sounds like you're looking for is selectivity,
and you do that with tuned circuits. Or you did back when I was
learning this stuff. ;-)

Hope This Helps!
Rich

Yes, a tuned circuit, I am thinking. There is currently much more signal
than I need. Is an antenna tuner what I am looking for?

I hooked up 300 microhenries worth of RF choke, which reduces the entire
signal just a hair, but that is enough to knock the noise level down
considerably. I am not yet sure, but this *may* be all I need. BTW, did
some fiddling withe the anchor of the random wire, and decided it is more
like 45 - 50 feet total. I am planning on moving it, however, and placing
it under the eaves and off to the side of the aluminum rain gutter, which
may deflate it some. Right now I have signal to waste. That may change.

Thanks for the input. Working with RF is new to me.

Dave
[email protected]

 

[Rich Grise]

Yes, a tuned circuit, I am thinking. There is currently much more signal
than I need. Is an antenna tuner what I am looking for?

I hooked up 300 microhenries worth of RF choke, which reduces the entire
signal just a hair, but that is enough to knock the noise level down
considerably. I am not yet sure, but this *may* be all I need. BTW, did
some fiddling withe the anchor of the random wire, and decided it is more
like 45 - 50 feet total. I am planning on moving it, however, and placing
it under the eaves and off to the side of the aluminum rain gutter, which
may deflate it some. Right now I have signal to waste. That may change.

Thanks for the input. Working with RF is new to me.

Actually, if you've got good electrical conductivity, the aluminum
rain gutters themselves might make a passable antenna. Ground _one_
of the downspouts at the bottom end, and experiment with different
pickoff points along the length of the gutter. An antenna has
different impedances at different points along its length, based on
the wavelength of interest. And you'd add inductance and capacitance
as needed to make the whole thing resonant at the freq. you want.
(that's the philosophy of an "antenna tuner.")

It really wouldn't do any harm to look up some books on antennas
and stuff, like "The ARRL Antenna Book", and talk with practically
any radio amateur - those guys do this stuff all day long.

Cheers!
Rich

 

[Telamon]

Yes, a tuned circuit, I am thinking. There is currently much more signal
than I need. Is an antenna tuner what I am looking for?

I hooked up 300 microhenries worth of RF choke, which reduces the entire
signal just a hair, but that is enough to knock the noise level down
considerably. I am not yet sure, but this *may* be all I need. BTW, did
some fiddling withe the anchor of the random wire, and decided it is more
like 45 - 50 feet total. I am planning on moving it, however, and placing
it under the eaves and off to the side of the aluminum rain gutter, which
may deflate it some. Right now I have signal to waste. That may change.

Thanks for the input. Working with RF is new to me.

Anytime you have to much signal and want to reduce it you employ an
attenuator. For coax it would be composed of three resistors in a pie
network. You would select values that would cause the input and output
resistance of the attenuator to appear 50 ohms using the source and load
impedance of the antenna and receiver so it would not generate
reflections. Additionally the resistor values would provide the voltage
division required. All calculations use ohms law. Since the radios S
meter basically is a reflection of the signal voltage a 6 dB attenuator
would cause the meter deflection to be about half what it was without
the attenuator.

If you don't care about reflections then you can make a quick and dirty
variable attenuator using a potentiometer from Radio Shack. The outer
shield of the coax goes to the same radio connection and one end of the
potentiometer, the other end of the potentiometer goes to the coax
center conductor and the potentiometer wiper goes to the radio input
where the coax center conductor would normally go. A 10K potentiometer
would be good to use.

 

[-=jd=-]

{snippage}

If you don't care about reflections then you can make a quick and dirty
variable attenuator using a potentiometer from Radio Shack. The outer
shield of the coax goes to the same radio connection and one end of the
potentiometer, the other end of the potentiometer goes to the coax
center conductor and the potentiometer wiper goes to the radio input
where the coax center conductor would normally go. A 10K potentiometer
would be good to use.

I just made one of these. I got a 10k and a 100k pot because I didn't know
which one I would need, ad Rat-Shack had both. It turns out the 100K pot
suits me better. However, they're so cheap, get both and try each to see
which one works best for your situation/receiver.

So far, it works like a charm for me. I can either have no attenuation
(signal at full strength) or I can reduce the signal strength as much as I
need.

I haven't noticed any "reflections"... yet... I may have them... ummm...
ok, I don't even know what they are... Are they like harmonics?

-=jd=-
"Stumbling through SWL like a 4-year old in the dark..."

 

[Dave]

Actually, if you've got good electrical conductivity, the aluminum
rain gutters themselves might make a passable antenna. Ground _one_
of the downspouts at the bottom end, and experiment with different
pickoff points along the length of the gutter. An antenna has
different impedances at different points along its length, based on
the wavelength of interest. And you'd add inductance and capacitance
as needed to make the whole thing resonant at the freq. you want.
(that's the philosophy of an "antenna tuner.")

It really wouldn't do any harm to look up some books on antennas
and stuff, like "The ARRL Antenna Book", and talk with practically
any radio amateur - those guys do this stuff all day long.

Cheers!
Rich

I thought about trying to use the rain gutter as an antenna, but decided
against it for a number of reasons. The main reason was that I didn't want
to fiddle with trying to get good electrical connections between the many
pieces. Anything I did to it would have to be most asthetically appealing,
or I would never hear the end of it from my wife. She absolutely hates
having a piece of wife laying across the roof, and can't wait until I fix it
in place underneath the eaves.

I have a copy of the latest edition of Joe Carr's Practical Antenna Handbook
(I think that's what it's called) but don't have a tremendous amount of time
to spend with it. So much else to do... I need to set aside a couple hours
every night and just plow through it.

Thanks again for your input.

Dave
[email protected]

 

[Dave]

Anytime you have to much signal and want to reduce it you employ an
attenuator. For coax it would be composed of three resistors in a pie
network. You would select values that would cause the input and output
resistance of the attenuator to appear 50 ohms using the source and load
impedance of the antenna and receiver so it would not generate
reflections. Additionally the resistor values would provide the voltage
division required. All calculations use ohms law. Since the radios S
meter basically is a reflection of the signal voltage a 6 dB attenuator
would cause the meter deflection to be about half what it was without
the attenuator.

If you don't care about reflections then you can make a quick and dirty
variable attenuator using a potentiometer from Radio Shack. The outer
shield of the coax goes to the same radio connection and one end of the
potentiometer, the other end of the potentiometer goes to the coax
center conductor and the potentiometer wiper goes to the radio input
where the coax center conductor would normally go. A 10K potentiometer
would be good to use.

Thanks for the info. Not really sure which avenue I am going to persue at
this point. Trying to sort out all the options. I appreciate the input.

Dave
[email protected]

 

[-=jd=-]

She absolutely hates
having a piece of wife laying across the roof, and can't wait until I
fix it in place underneath the eaves.

There's a few different ways I could interpret that!!


-=jd=-

 

[Dave]

There's a few different ways I could interpret that!!


-=jd=-
--

LOL! I meant to say "a piece of WIRE..." Guess I was thinking something
else.

Dave
[email protected]

 

[-=jd=-]

LOL! I meant to say "a piece of WIRE..." Guess I was thinking
something else.

Dave
[email protected]

Ha! At first I was going to ask if she improved your reception much, but
was afraid of the possible spike in domestic-violence related 911 calls
when others tried to duplicate your results. ;-)


-=jd=-

 

[RHF]

DAVE,

So you have a Sangean ATS -505 and your 'problems' are Antenna
Overload and Noise Levels.
* Consider a 'smaller' shorter Antenna will reduce the overload problems.
* Consider a Low Noise Antenna Design will reduce the noise problems.
{LOW NOISE SWL ANTENNA - popularized by John Doty}
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/2
http://www.anarc.org/naswa/badx/antennas/low-noise_antenna.html

For a simple 'external' Shortwave Antenna to use with the Sangean
ATS-505 'portable' Shortwave Radio, using the 1/8" Mono-Jack
External Shortwave Antenna Input. Consider a Random Wire
Antenna using a Matching Transformer and Ground for Low Noise
and Wide Range Frequency Coverage.

PARTS: Here is a simple SWL Antenna Idea using a few common
RadioShack TV Antenna type parts:
Catalog #: 15-1174 = 25~50 Foot 300 Ohm (Flat) TV Twin-Lead
Catalog #: 15-1230 = 75 to 300 Ohm Matching Transformer (2 Ea.)
Catalog #: 274-286 = 1/8" Mono (Phone) Plug
Catalog #: Catalog #: 15-1579 = 25~50 Foot Coax Cable with F Connectors

NOTE: This is an 'improved' Random Wire SWL Antenna using "TV"
Parts for 'reducing' Man Made Noise (RFI EMF) that is generated in
or near most modern homes/buildings.

EXTERNAL "OUTSIDE" SWL ANTENNA:

The Antenna [Loop] Element is Stretched outside Horizontally or
in the shape of an Inverted "L". The Antenna [Loop] Element is
formed by connecting the two ends of the Far-End of the 300 Ohm
TV Twin Lead. This forms a continuous single skinny horizontal
flat loop going out and back. This also represents a Balance
300 Ohm Load to match-up with the 300 Ohm Matching Transformer.
The 300 Ohm Leads of the Matching Transformer connects to the
Near-Ends of the Loop Antenna Element. The 75 Ohm F Connector
of the Matching Transformer is connected to the 75 Ohm Coax Cable.
The 75 Ohm Coax Cable acts as the Lead-In from the Outside to
inside the house to the radio shack. The other end of the 75
Ohm Coax Cable is connected to the 75 Ohm F Connector of the
Matching Transformer. The Radio-End of the Coax Cable F Connector
would connect to a 75 to 300 Ohm Matching Transformer; and then
into a 1/8" Mono-Plug to plug into the Radio.
NOTE: Using the 300 Ohm TV Twin Lead in a Skinny Flat Loop
Antenna should balance-cancel-reduce most man made noise and be
Omni-Directional.

GROUND: Find a Grounding Point within/about your dwelling.
Secure a good Grounding Point for your Radio and Antenna.
Run a Heavy & Short Ground Wire to your Radio. Locate the
Ground Terminal on your Radio. Attach/Secure the Ground Wire
to the Coax Cable and/or the Radio's Ground Terminal.

FWIW: This Antenna using common TV Antenna type parts should
be effective as SWL Antennas above 5MHz and beyond 30MHz.


iane ~ RHF
..
Some Say: On A Clear Day You Can See Forever.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/502
I BELIEVE: On A Clear Night...
You Can Hear Forever and Beyond - The Beyond !
..
..

I recently hooked up a thirty-six foot (plus or minus a couple of feet)
piece of four-stranded wire with alligator clip to the internal "whip"
antenna of my portable shortwave receiver, for the extra performance such a
device offered. It works so well that I now cannot usually use my "DX"
setting because of all the background noise (sounds like hundreds of other
broadcasts vying for attention.) I don't know the frequency source of all
this background noise, but would like to filter out as much of it as I can.
One manufacturer of a similar "wind-up" antenna adds a capacitor to the wire
in order to lower the resonance frequency of the wire. If I were going to
try something similar (adding a capacitor, in series) in an attempt to bring
the resonance of the wire down into the 30 MHz range, what size (roughly)
capacitor should I use? Should I just try a few with different ranges, or
does anyone here have any suggestions?

TIA

Cross-posted between sci.electronics.basics and rec.radio.shortwave


Dave
[email protected]

..

 

[Dave]

Wow. Thank you for these concise and clear directions. One thing though, I
really don't *think* I am overloading the set. Only problem I have is
digging the weak (but desired) signals our of the background noise
surrounding them. In another post I mentioned Voice of Korea's Central and
South American broadcast as the point of interest. It is just at the same
level as the background noise that doesn't interfere with other broadcasts
like the BBC on 5975 kHz or Radio Havana, Cuba on 9820 kHz (or Radio China
International, originally from Taiwan and rebroadcast through some place in
Florida, which frequency I can't remember at the moment.) It is only the
weak signals I am having trouble with. If I tune into WWV our of Ft.
Collins CO I can barely make out some out-of-band signals coming in, but
they are so weak as to be vanishing. Does this still sound like
overloading? Because the troublesom signals are also very weak, I am
thinking that a preselector will probably take care of my problems. (I am
still tempted to abandon my random wire and install your suggested antenna
just because it sounds so much more sophisticated. Will let you know.)

Thanks for the feedback.

Dave
[email protected]

DAVE,

So you have a Sangean ATS -505 and your 'problems' are Antenna
Overload and Noise Levels.
* Consider a 'smaller' shorter Antenna will reduce the overload problems.
* Consider a Low Noise Antenna Design will reduce the noise problems.
{LOW NOISE SWL ANTENNA - popularized by John Doty}
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/2
http://www.anarc.org/naswa/badx/antennas/low-noise_antenna.html

For a simple 'external' Shortwave Antenna to use with the Sangean
ATS-505 'portable' Shortwave Radio, using the 1/8" Mono-Jack
External Shortwave Antenna Input. Consider a Random Wire
Antenna using a Matching Transformer and Ground for Low Noise
and Wide Range Frequency Coverage.

PARTS: Here is a simple SWL Antenna Idea using a few common
RadioShack TV Antenna type parts:
Catalog #: 15-1174 = 25~50 Foot 300 Ohm (Flat) TV Twin-Lead
Catalog #: 15-1230 = 75 to 300 Ohm Matching Transformer (2 Ea.)
Catalog #: 274-286 = 1/8" Mono (Phone) Plug
Catalog #: Catalog #: 15-1579 = 25~50 Foot Coax Cable with F Connectors

NOTE: This is an 'improved' Random Wire SWL Antenna using "TV"
Parts for 'reducing' Man Made Noise (RFI EMF) that is generated in
or near most modern homes/buildings.

EXTERNAL "OUTSIDE" SWL ANTENNA:

The Antenna [Loop] Element is Stretched outside Horizontally or
in the shape of an Inverted "L". The Antenna [Loop] Element is
formed by connecting the two ends of the Far-End of the 300 Ohm
TV Twin Lead. This forms a continuous single skinny horizontal
flat loop going out and back. This also represents a Balance
300 Ohm Load to match-up with the 300 Ohm Matching Transformer.
The 300 Ohm Leads of the Matching Transformer connects to the
Near-Ends of the Loop Antenna Element. The 75 Ohm F Connector
of the Matching Transformer is connected to the 75 Ohm Coax Cable.
The 75 Ohm Coax Cable acts as the Lead-In from the Outside to
inside the house to the radio shack. The other end of the 75
Ohm Coax Cable is connected to the 75 Ohm F Connector of the
Matching Transformer. The Radio-End of the Coax Cable F Connector
would connect to a 75 to 300 Ohm Matching Transformer; and then
into a 1/8" Mono-Plug to plug into the Radio.
NOTE: Using the 300 Ohm TV Twin Lead in a Skinny Flat Loop
Antenna should balance-cancel-reduce most man made noise and be
Omni-Directional.

GROUND: Find a Grounding Point within/about your dwelling.
Secure a good Grounding Point for your Radio and Antenna.
Run a Heavy & Short Ground Wire to your Radio. Locate the
Ground Terminal on your Radio. Attach/Secure the Ground Wire
to the Coax Cable and/or the Radio's Ground Terminal.

FWIW: This Antenna using common TV Antenna type parts should
be effective as SWL Antennas above 5MHz and beyond 30MHz.


iane ~ RHF
.
Some Say: On A Clear Day You Can See Forever.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/502
I BELIEVE: On A Clear Night...
You Can Hear Forever and Beyond - The Beyond !
.
.

I recently hooked up a thirty-six foot (plus or minus a couple of feet)
piece of four-stranded wire with alligator clip to the internal "whip"
antenna of my portable shortwave receiver, for the extra performance such a
device offered. It works so well that I now cannot usually use my "DX"
setting because of all the background noise (sounds like hundreds of other
broadcasts vying for attention.) I don't know the frequency source of all
this background noise, but would like to filter out as much of it as I can.
One manufacturer of a similar "wind-up" antenna adds a capacitor to the wire
in order to lower the resonance frequency of the wire. If I were going to
try something similar (adding a capacitor, in series) in an attempt to bring
the resonance of the wire down into the 30 MHz range, what size (roughly)
capacitor should I use? Should I just try a few with different ranges, or
does anyone here have any suggestions?

TIA

Cross-posted between sci.electronics.basics and rec.radio.shortwave


Dave
[email protected]

.

 

[Dave]

Just printed your instructions in prep for a trip to the store, and have one
question: The twin-lead is 300 ohm, connected to a 300/75 ohm matching
transformer, connected to 75 ohm coax. Then the coax is connectect to
another 75/300 ohm matching transformer, which is connected to the 1/8" mono
plug to plug into the external antenna jack? Is the 1/8" jack a 300 ohm
impedance connection? Somehow I thought it would be 50 or 75 ohms, like
coax. Do I need some 300 ohm coax to put between the second transformer and
the plug?

Thanks,

Dave
[email protected]

DAVE,

So you have a Sangean ATS -505 and your 'problems' are Antenna
Overload and Noise Levels.
* Consider a 'smaller' shorter Antenna will reduce the overload problems.
* Consider a Low Noise Antenna Design will reduce the noise problems.
{LOW NOISE SWL ANTENNA - popularized by John Doty}
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/2
http://www.anarc.org/naswa/badx/antennas/low-noise_antenna.html

For a simple 'external' Shortwave Antenna to use with the Sangean
ATS-505 'portable' Shortwave Radio, using the 1/8" Mono-Jack
External Shortwave Antenna Input. Consider a Random Wire
Antenna using a Matching Transformer and Ground for Low Noise
and Wide Range Frequency Coverage.

PARTS: Here is a simple SWL Antenna Idea using a few common
RadioShack TV Antenna type parts:
Catalog #: 15-1174 = 25~50 Foot 300 Ohm (Flat) TV Twin-Lead
Catalog #: 15-1230 = 75 to 300 Ohm Matching Transformer (2 Ea.)
Catalog #: 274-286 = 1/8" Mono (Phone) Plug
Catalog #: Catalog #: 15-1579 = 25~50 Foot Coax Cable with F Connectors

NOTE: This is an 'improved' Random Wire SWL Antenna using "TV"
Parts for 'reducing' Man Made Noise (RFI EMF) that is generated in
or near most modern homes/buildings.

EXTERNAL "OUTSIDE" SWL ANTENNA:

The Antenna [Loop] Element is Stretched outside Horizontally or
in the shape of an Inverted "L". The Antenna [Loop] Element is
formed by connecting the two ends of the Far-End of the 300 Ohm
TV Twin Lead. This forms a continuous single skinny horizontal
flat loop going out and back. This also represents a Balance
300 Ohm Load to match-up with the 300 Ohm Matching Transformer.
The 300 Ohm Leads of the Matching Transformer connects to the
Near-Ends of the Loop Antenna Element. The 75 Ohm F Connector
of the Matching Transformer is connected to the 75 Ohm Coax Cable.
The 75 Ohm Coax Cable acts as the Lead-In from the Outside to
inside the house to the radio shack. The other end of the 75
Ohm Coax Cable is connected to the 75 Ohm F Connector of the
Matching Transformer. The Radio-End of the Coax Cable F Connector
would connect to a 75 to 300 Ohm Matching Transformer; and then
into a 1/8" Mono-Plug to plug into the Radio.
NOTE: Using the 300 Ohm TV Twin Lead in a Skinny Flat Loop
Antenna should balance-cancel-reduce most man made noise and be
Omni-Directional.

GROUND: Find a Grounding Point within/about your dwelling.
Secure a good Grounding Point for your Radio and Antenna.
Run a Heavy & Short Ground Wire to your Radio. Locate the
Ground Terminal on your Radio. Attach/Secure the Ground Wire
to the Coax Cable and/or the Radio's Ground Terminal.

FWIW: This Antenna using common TV Antenna type parts should
be effective as SWL Antennas above 5MHz and beyond 30MHz.


iane ~ RHF
.
Some Say: On A Clear Day You Can See Forever.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/502
I BELIEVE: On A Clear Night...
You Can Hear Forever and Beyond - The Beyond !
.
.

I recently hooked up a thirty-six foot (plus or minus a couple of feet)
piece of four-stranded wire with alligator clip to the internal "whip"
antenna of my portable shortwave receiver, for the extra performance such a
device offered. It works so well that I now cannot usually use my "DX"
setting because of all the background noise (sounds like hundreds of other
broadcasts vying for attention.) I don't know the frequency source of all
this background noise, but would like to filter out as much of it as I can.
One manufacturer of a similar "wind-up" antenna adds a capacitor to the wire
in order to lower the resonance frequency of the wire. If I were going to
try something similar (adding a capacitor, in series) in an attempt to bring
the resonance of the wire down into the 30 MHz range, what size (roughly)
capacitor should I use? Should I just try a few with different ranges, or
does anyone here have any suggestions?

TIA

Cross-posted between sci.electronics.basics and rec.radio.shortwave


Dave
[email protected]

.

 

[-=jd=-]

Just printed your instructions in prep for a trip to the store, and have
one question: The twin-lead is 300 ohm, connected to a 300/75 ohm
matching transformer, connected to 75 ohm coax. Then the coax is
connectect to another 75/300 ohm matching transformer, which is
connected to the 1/8" mono plug to plug into the external antenna jack?
Is the 1/8" jack a 300 ohm impedance connection? Somehow I thought it
would be 50 or 75 ohms, like coax. Do I need some 300 ohm coax to put
between the second transformer and the plug?

Thanks,

Dave
[email protected]

Speaking of which, how would one go about measuring a home-brewed
transformer? I've wound a few, but I'd like to be able to measure them
(somehow) to see if I wound them correctly for the desired impedence. From
what I'm seeing, a regular volt-ohm meter is not the proper device for the
job...

-=jd=-

 

[RHF]

DAVE,

At the Radio-End of the 75 Ohm Coax Cable "F" Connector you can
use a standard 75-300 Ohm Matching Transformer and then connect
it to a Mini-TV External Antenna Adapter. [ RadioShack {Canada}
Catalog #: 15-1148 = 75 to 300 Ohm Mini-Plug Adapter ]
MINI-PLUG-ADAPTER=> http://tinyurl.com/23nsh

FWIW: Some RadioShacks and other electronics stores have an "Adapter"
that directly connects an "F" Connector to a /18" Mono-Phone-Jack.


Please Note: That a 'connection' to a good earthen Ground is
needed to one of the "F" Connectors of the 75 Ohm Coax Cable.

You can use a #14 Wire with a RadioShack Catalog #: 278-002
Heavy-Duty Claw Insulated Test/Jumper Cable Sets. Or, simply
use several windings of bare wire wrapped around one of the "F"
Connectors with a small metal hose clamp to secure the wire.


iane ~ RHF
..
..

Just printed your instructions in prep for a trip to the store, and have one
question: The twin-lead is 300 ohm, connected to a 300/75 ohm matching
transformer, connected to 75 ohm coax. Then the coax is connectect to
another 75/300 ohm matching transformer, which is connected to the 1/8" mono
plug to plug into the external antenna jack? Is the 1/8" jack a 300 ohm
impedance connection? Somehow I thought it would be 50 or 75 ohms, like
coax. Do I need some 300 ohm coax to put between the second transformer and
the plug?

Thanks,

Dave
[email protected]

DAVE,

So you have a Sangean ATS -505 and your 'problems' are Antenna
Overload and Noise Levels.
* Consider a 'smaller' shorter Antenna will reduce the overload problems.
* Consider a Low Noise Antenna Design will reduce the noise problems.
{LOW NOISE SWL ANTENNA - popularized by John Doty}
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/2
http://www.anarc.org/naswa/badx/antennas/low-noise_antenna.html

For a simple 'external' Shortwave Antenna to use with the Sangean
ATS-505 'portable' Shortwave Radio, using the 1/8" Mono-Jack
External Shortwave Antenna Input. Consider a Random Wire
Antenna using a Matching Transformer and Ground for Low Noise
and Wide Range Frequency Coverage.

PARTS: Here is a simple SWL Antenna Idea using a few common
RadioShack TV Antenna type parts:
Catalog #: 15-1174 = 25~50 Foot 300 Ohm (Flat) TV Twin-Lead
Catalog #: 15-1230 = 75 to 300 Ohm Matching Transformer (2 Ea.)
Catalog #: 274-286 = 1/8" Mono (Phone) Plug
Catalog #: Catalog #: 15-1579 = 25~50 Foot Coax Cable with F Connectors

NOTE: This is an 'improved' Random Wire SWL Antenna using "TV"
Parts for 'reducing' Man Made Noise (RFI EMF) that is generated in
or near most modern homes/buildings.

EXTERNAL "OUTSIDE" SWL ANTENNA:

The Antenna [Loop] Element is Stretched outside Horizontally or
in the shape of an Inverted "L". The Antenna [Loop] Element is
formed by connecting the two ends of the Far-End of the 300 Ohm
TV Twin Lead. This forms a continuous single skinny horizontal
flat loop going out and back. This also represents a Balance
300 Ohm Load to match-up with the 300 Ohm Matching Transformer.
The 300 Ohm Leads of the Matching Transformer connects to the
Near-Ends of the Loop Antenna Element. The 75 Ohm F Connector
of the Matching Transformer is connected to the 75 Ohm Coax Cable.
The 75 Ohm Coax Cable acts as the Lead-In from the Outside to
inside the house to the radio shack. The other end of the 75
Ohm Coax Cable is connected to the 75 Ohm F Connector of the
Matching Transformer. The Radio-End of the Coax Cable F Connector
would connect to a 75 to 300 Ohm Matching Transformer; and then
into a 1/8" Mono-Plug to plug into the Radio.
NOTE: Using the 300 Ohm TV Twin Lead in a Skinny Flat Loop
Antenna should balance-cancel-reduce most man made noise and be
Omni-Directional.

GROUND: Find a Grounding Point within/about your dwelling.
Secure a good Grounding Point for your Radio and Antenna.
Run a Heavy & Short Ground Wire to your Radio. Locate the
Ground Terminal on your Radio. Attach/Secure the Ground Wire
to the Coax Cable and/or the Radio's Ground Terminal.

FWIW: This Antenna using common TV Antenna type parts should
be effective as SWL Antennas above 5MHz and beyond 30MHz.


iane ~ RHF
.
Some Say: On A Clear Day You Can See Forever.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/502
I BELIEVE: On A Clear Night...
You Can Hear Forever and Beyond - The Beyond !
.
.

I recently hooked up a thirty-six foot (plus or minus a couple of feet)
piece of four-stranded wire with alligator clip to the internal "whip"
antenna of my portable shortwave receiver, for the extra performance such a
device offered. It works so well that I now cannot usually use my "DX"
setting because of all the background noise (sounds like hundreds of other
broadcasts vying for attention.) I don't know the frequency source of all
this background noise, but would like to filter out as much of it as I can.
One manufacturer of a similar "wind-up" antenna adds a capacitor to the wire
in order to lower the resonance frequency of the wire. If I were going to
try something similar (adding a capacitor, in series) in an attempt to bring
the resonance of the wire down into the 30 MHz range, what size (roughly)
capacitor should I use? Should I just try a few with different ranges, or
does anyone here have any suggestions?

TIA

Cross-posted between sci.electronics.basics and rec.radio.shortwave


Dave
[email protected]

.

 

[Dave]

DAVE,

At the Radio-End of the 75 Ohm Coax Cable "F" Connector you can
use a standard 75-300 Ohm Matching Transformer and then connect
it to a Mini-TV External Antenna Adapter. [ RadioShack {Canada}
Catalog #: 15-1148 = 75 to 300 Ohm Mini-Plug Adapter ]
MINI-PLUG-ADAPTER=> http://tinyurl.com/23nsh

FWIW: Some RadioShacks and other electronics stores have an "Adapter"
that directly connects an "F" Connector to a /18" Mono-Phone-Jack.


Please Note: That a 'connection' to a good earthen Ground is
needed to one of the "F" Connectors of the 75 Ohm Coax Cable.

You can use a #14 Wire with a RadioShack Catalog #: 278-002
Heavy-Duty Claw Insulated Test/Jumper Cable Sets. Or, simply
use several windings of bare wire wrapped around one of the "F"
Connectors with a small metal hose clamp to secure the wire.


iane ~ RHF
.
.

Just printed your instructions in prep for a trip to the store, and have one
question: The twin-lead is 300 ohm, connected to a 300/75 ohm matching
transformer, connected to 75 ohm coax. Then the coax is connectect to
another 75/300 ohm matching transformer, which is connected to the 1/8" mono
plug to plug into the external antenna jack? Is the 1/8" jack a 300 ohm
impedance connection? Somehow I thought it would be 50 or 75 ohms, like
coax. Do I need some 300 ohm coax to put between the second transformer and
the plug?

Thanks,

Dave
[email protected]

DAVE,

So you have a Sangean ATS -505 and your 'problems' are Antenna
Overload and Noise Levels.
* Consider a 'smaller' shorter Antenna will reduce the overload problems.
* Consider a Low Noise Antenna Design will reduce the noise problems.
{LOW NOISE SWL ANTENNA - popularized by John Doty}
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/2
http://www.anarc.org/naswa/badx/antennas/low-noise_antenna.html

For a simple 'external' Shortwave Antenna to use with the Sangean
ATS-505 'portable' Shortwave Radio, using the 1/8" Mono-Jack
External Shortwave Antenna Input. Consider a Random Wire
Antenna using a Matching Transformer and Ground for Low Noise
and Wide Range Frequency Coverage.

PARTS: Here is a simple SWL Antenna Idea using a few common
RadioShack TV Antenna type parts:
Catalog #: 15-1174 = 25~50 Foot 300 Ohm (Flat) TV Twin-Lead
Catalog #: 15-1230 = 75 to 300 Ohm Matching Transformer (2 Ea.)
Catalog #: 274-286 = 1/8" Mono (Phone) Plug
Catalog #: Catalog #: 15-1579 = 25~50 Foot Coax Cable with F Connectors

NOTE: This is an 'improved' Random Wire SWL Antenna using "TV"
Parts for 'reducing' Man Made Noise (RFI EMF) that is generated in
or near most modern homes/buildings.

EXTERNAL "OUTSIDE" SWL ANTENNA:

The Antenna [Loop] Element is Stretched outside Horizontally or
in the shape of an Inverted "L". The Antenna [Loop] Element is
formed by connecting the two ends of the Far-End of the 300 Ohm
TV Twin Lead. This forms a continuous single skinny horizontal
flat loop going out and back. This also represents a Balance
300 Ohm Load to match-up with the 300 Ohm Matching Transformer.
The 300 Ohm Leads of the Matching Transformer connects to the
Near-Ends of the Loop Antenna Element. The 75 Ohm F Connector
of the Matching Transformer is connected to the 75 Ohm Coax Cable.
The 75 Ohm Coax Cable acts as the Lead-In from the Outside to
inside the house to the radio shack. The other end of the 75
Ohm Coax Cable is connected to the 75 Ohm F Connector of the
Matching Transformer. The Radio-End of the Coax Cable F Connector
would connect to a 75 to 300 Ohm Matching Transformer; and then
into a 1/8" Mono-Plug to plug into the Radio.
NOTE: Using the 300 Ohm TV Twin Lead in a Skinny Flat Loop
Antenna should balance-cancel-reduce most man made noise and be
Omni-Directional.

GROUND: Find a Grounding Point within/about your dwelling.
Secure a good Grounding Point for your Radio and Antenna.
Run a Heavy & Short Ground Wire to your Radio. Locate the
Ground Terminal on your Radio. Attach/Secure the Ground Wire
to the Coax Cable and/or the Radio's Ground Terminal.

FWIW: This Antenna using common TV Antenna type parts should
be effective as SWL Antennas above 5MHz and beyond 30MHz.


iane ~ RHF
.
Some Say: On A Clear Day You Can See Forever.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/502
I BELIEVE: On A Clear Night...
You Can Hear Forever and Beyond - The Beyond !
.
.
= = = I recently hooked up a thirty-six foot (plus or minus a couple of feet)
piece of four-stranded wire with alligator clip to the internal "whip"
antenna of my portable shortwave receiver, for the extra performance such a
device offered. It works so well that I now cannot usually use my "DX"
setting because of all the background noise (sounds like hundreds of other
broadcasts vying for attention.) I don't know the frequency source

of
all

this background noise, but would like to filter out as much of it as

I
can.

One manufacturer of a similar "wind-up" antenna adds a capacitor to

the
wire

in order to lower the resonance frequency of the wire. If I were

going
to

try something similar (adding a capacitor, in series) in an attempt

to
bring

the resonance of the wire down into the 30 MHz range, what size (roughly)
capacitor should I use? Should I just try a few with different

ranges,
or

does anyone here have any suggestions?

TIA

Cross-posted between sci.electronics.basics and rec.radio.shortwave


Dave
[email protected]

.

 

[Dave]

Argh. I just posted an empty message. Sorry. Please ignore.

Thanks for the info. I picked up a 300/75 ohm mini-plug adapter at the
store, but failed to get the second 75/300 ohm matching transformer to go
between it and the coax. Tomorrow.

Question: I have an odd situation, and can either install a 1/4 wave dipole
or a half-wave "random" wire loop (I think). Right now the grounding rod is
immediately below where the dipole would go, and I think I could drop the
300 ohm twin-lead down to it where I would ground one side (I think I have
this right, please correct me if I am wrong). At that same point I would
ground the shield of the coax, and hook the other side of the dipole to the
coax center conductor. Coax would travel 10 feet or so to my window and the
radio. Other option involves moving the grounding rod and doing something
similar with the twin-lead as a long loop, grounding one side of that and
coax from the other side of the window. Assuming these are workable ideas,
which do you think would work best? Again, [please don't hesitate to tell
me if I am full of crap. RF is new to me.

I really do appreciate your help. Like I said before, RF is totally new to
me.

Thanks,

Dave
[email protected]

DAVE,

At the Radio-End of the 75 Ohm Coax Cable "F" Connector you can
use a standard 75-300 Ohm Matching Transformer and then connect
it to a Mini-TV External Antenna Adapter. [ RadioShack {Canada}
Catalog #: 15-1148 = 75 to 300 Ohm Mini-Plug Adapter ]
MINI-PLUG-ADAPTER=> http://tinyurl.com/23nsh

FWIW: Some RadioShacks and other electronics stores have an "Adapter"
that directly connects an "F" Connector to a /18" Mono-Phone-Jack.


Please Note: That a 'connection' to a good earthen Ground is
needed to one of the "F" Connectors of the 75 Ohm Coax Cable.

You can use a #14 Wire with a RadioShack Catalog #: 278-002
Heavy-Duty Claw Insulated Test/Jumper Cable Sets. Or, simply
use several windings of bare wire wrapped around one of the "F"
Connectors with a small metal hose clamp to secure the wire.


iane ~ RHF
.
.

Just printed your instructions in prep for a trip to the store, and have one
question: The twin-lead is 300 ohm, connected to a 300/75 ohm matching
transformer, connected to 75 ohm coax. Then the coax is connectect to
another 75/300 ohm matching transformer, which is connected to the 1/8" mono
plug to plug into the external antenna jack? Is the 1/8" jack a 300 ohm
impedance connection? Somehow I thought it would be 50 or 75 ohms, like
coax. Do I need some 300 ohm coax to put between the second transformer and
the plug?

Thanks,

Dave
[email protected]

DAVE,

So you have a Sangean ATS -505 and your 'problems' are Antenna
Overload and Noise Levels.
* Consider a 'smaller' shorter Antenna will reduce the overload problems.
* Consider a Low Noise Antenna Design will reduce the noise problems.
{LOW NOISE SWL ANTENNA - popularized by John Doty}
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/2
http://www.anarc.org/naswa/badx/antennas/low-noise_antenna.html

For a simple 'external' Shortwave Antenna to use with the Sangean
ATS-505 'portable' Shortwave Radio, using the 1/8" Mono-Jack
External Shortwave Antenna Input. Consider a Random Wire
Antenna using a Matching Transformer and Ground for Low Noise
and Wide Range Frequency Coverage.

PARTS: Here is a simple SWL Antenna Idea using a few common
RadioShack TV Antenna type parts:
Catalog #: 15-1174 = 25~50 Foot 300 Ohm (Flat) TV Twin-Lead
Catalog #: 15-1230 = 75 to 300 Ohm Matching Transformer (2 Ea.)
Catalog #: 274-286 = 1/8" Mono (Phone) Plug
Catalog #: Catalog #: 15-1579 = 25~50 Foot Coax Cable with F Connectors

NOTE: This is an 'improved' Random Wire SWL Antenna using "TV"
Parts for 'reducing' Man Made Noise (RFI EMF) that is generated in
or near most modern homes/buildings.

EXTERNAL "OUTSIDE" SWL ANTENNA:

The Antenna [Loop] Element is Stretched outside Horizontally or
in the shape of an Inverted "L". The Antenna [Loop] Element is
formed by connecting the two ends of the Far-End of the 300 Ohm
TV Twin Lead. This forms a continuous single skinny horizontal
flat loop going out and back. This also represents a Balance
300 Ohm Load to match-up with the 300 Ohm Matching Transformer.
The 300 Ohm Leads of the Matching Transformer connects to the
Near-Ends of the Loop Antenna Element. The 75 Ohm F Connector
of the Matching Transformer is connected to the 75 Ohm Coax Cable.
The 75 Ohm Coax Cable acts as the Lead-In from the Outside to
inside the house to the radio shack. The other end of the 75
Ohm Coax Cable is connected to the 75 Ohm F Connector of the
Matching Transformer. The Radio-End of the Coax Cable F Connector
would connect to a 75 to 300 Ohm Matching Transformer; and then
into a 1/8" Mono-Plug to plug into the Radio.
NOTE: Using the 300 Ohm TV Twin Lead in a Skinny Flat Loop
Antenna should balance-cancel-reduce most man made noise and be
Omni-Directional.

GROUND: Find a Grounding Point within/about your dwelling.
Secure a good Grounding Point for your Radio and Antenna.
Run a Heavy & Short Ground Wire to your Radio. Locate the
Ground Terminal on your Radio. Attach/Secure the Ground Wire
to the Coax Cable and/or the Radio's Ground Terminal.

FWIW: This Antenna using common TV Antenna type parts should
be effective as SWL Antennas above 5MHz and beyond 30MHz.


iane ~ RHF
.
Some Say: On A Clear Day You Can See Forever.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/502
I BELIEVE: On A Clear Night...
You Can Hear Forever and Beyond - The Beyond !
.
.
= = = I recently hooked up a thirty-six foot (plus or minus a couple of feet)
piece of four-stranded wire with alligator clip to the internal "whip"
antenna of my portable shortwave receiver, for the extra performance such a
device offered. It works so well that I now cannot usually use my "DX"
setting because of all the background noise (sounds like hundreds of other
broadcasts vying for attention.) I don't know the frequency source

of
all

this background noise, but would like to filter out as much of it as

I
can.

One manufacturer of a similar "wind-up" antenna adds a capacitor to

the
wire

in order to lower the resonance frequency of the wire. If I were

going
to

try something similar (adding a capacitor, in series) in an attempt

to
bring

the resonance of the wire down into the 30 MHz range, what size (roughly)
capacitor should I use? Should I just try a few with different

ranges,
or

does anyone here have any suggestions?

TIA

Cross-posted between sci.electronics.basics and rec.radio.shortwave


Dave
[email protected]

.

 

[RHF]

Argh. I just posted an empty message. Sorry. Please ignore.

Thanks for the info. I picked up a 300/75 ohm mini-plug adapter at the
store, but failed to get the second 75/300 ohm matching transformer to go
between it and the coax. Tomorrow.

Question: I have an odd situation, and can either install a 1/4 wave dipole
or a half-wave "random" wire loop (I think).

A "Random" Wire Antenna is simply that = Any Length that FITS
the Space that is Available to put up and Antenna.

For these general types of Low Noise Antennas. The Inverted "L"
{Shaped} Antenna lends itself to the design the best.

Run the Horizontal Arm for as long as you can at your roof line.

Run the Vertial Leg down to your Ground Rod Location.

Make your 'primary' Grounding Point "Connection".

Run your Coax Cable from the Grounding Point to your Radio.
..
..

Right now the grounding rod is immediately below where the
dipole would go, and I think I could drop the 300 ohm twin-lead
down to it where I would ground one side (I think I have
this right, please correct me if I am wrong).

Initially do NOT Ground the 300 Ohm Twin Lead.
[ This is the Antenna Side of the Matching Transformer. ]
The Near-End of the 300 Ohm Twin Lead is connected across the
300 Ohm-Side of the Matching Transformer; and the other Far-End
of the 300 Ohm Twin Lead Wires are Connected (Joined) Together.
This forms a Long Shinny Loop Antenna Element.

FWIW: This is a very 'quiet' Antenna (almost sounds dead)
until you get spot on the frequency and then the signal is there.
..
..

At that same point I would ground the shield of the coax,
and hook the other side of the dipole to the coax center conductor.
Coax would travel 10 feet or so to my window and the radio.

First simply try Grounding the Outer-Shield of the Coax Cable ONLY.
..
..

Other option involves moving the grounding rod

IF - You move the Ground Rod. Place it so you can have an
Inverted "L" Antenna with the longest Horizontal Arm 'possible'.
(30 <60-90> 120 Feet)

iane ~ RHF
..
..

and doing something similar with the twin-lead as a long loop,
grounding one side of that and coax from the other side of the window.
Assuming these are workable ideas,
which do you think would work best? Again, [please don't hesitate to tell
me if I am full of crap. RF is new to me.

I really do appreciate your help. Like I said before, RF is totally new to
me.

Thanks,

Dave
[email protected]