starman wrote in message ...
Dave wrote:

I am using a DX-402 (aka Sangean ATS 505). I would be surprised if
it had a balanced antenna input, and have been thinking about just
clipping the external antenna to my whip after all. I hooked 20 feet
of 300 ohm twinlead to a 300/75 ohm transformer and miniplug last
night and plugged it in, but the signal strength was about half of
what my whip gives me. Therefore, the change in plans.

It would be a mistake to connect a good external antenna directly to the
whip. The receiver will almost certainly overload. You know the symptoms
for overloading now. If you build the low noise inverted-L, the coax can
be connected to the external antenna jack with a mini plug.

I was planning on running the vertical portion of twinlead that
went from ground level/grounding rod/coax up to the eaves over the
steel siding, but I could just as easily run the coax up the side of
the house, which would put all of the twinlead above the steel
siding. Still not "out in the open" but probably the best I can do.
Wifey doesn't want anything that obviously says "Hi there, I'm an
antenna!"

It's funny how women have an aversion to antennas. Must be an esthetic
thing. :-)

I am beginning to consider running the coax around to the end of the house and up that side, and laying the twinlead along the ridge of the roof from one end to the other. That would be a up a lot higher and a lot more "out in the open."


DAVE & STARMAN,

- - - - - - - - - - This would be my recommendation - - - - - - - - -
-

The horizontal section (single wire) of an inverted-L could also run
along the roof ridge. The vertical downlead wire would connect to one
end of the horizontal section and run down the end wall of the house to
the ground. The balun would be located near the ground next to a ground
rod. The coax would go from the balun to the receiver. That's the design
of the low noise inverted-L except it's better to locate the antenna
away from the house when you can.

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

Unless you have a Target Frequency and Country (Direction)
I do not recommend Dipole Antennas for general all around
broadband 500kHz to 30MHz Shortwave Listener "SWL" Antennas.

iane ~ RHF


No problem with the questions. It's nice to see an interesting on topic
thread for a change.

Thanks for the encouragement. I'm not yet sure what I will end up doing,
but I want to make the best decision possible.


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THANK YOU for this link! I especially like the schematic for the MFJ-956.
I'm definetly going to build that.

Dave


"CW" wrote in message
...
The word balun to describe this device, while quite common, is incorrect.
Go
he www.kc7nod.20m.com
Look for matching transformer.

"Dave" wrote in message
...
Away from the house is not possible. Even if it was, that would put it
near
the power lines. How would I build a balun? (Websites/links?)

So, a matching transformer is all I need? I have pretty much decided to use
300 ohm twinlead along the rood ridge with a 300/75 ohm matching transformer
to connect it to the coax, and more as needed between the coax and radio.
Will that honestly work?

Thanks,

Dave


"starman" wrote in message
...
It's an impedance matching transformer or unun. I use the word 'balun'
because most people haven't heard the term 'unun'.

CW wrote:

The word balun to describe this device, while quite common, is
incorrect. Go
he www.kc7nod.20m.com
Look for matching transformer.

"Dave" wrote in message
...
Away from the house is not possible. Even if it was, that would put
it
near
the power lines. How would I build a balun? (Websites/links?)


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I *think* I do. I'll definetly read more on the subject though.


Dave


"CW" wrote in message
...
We knew that you knew the difference. I was just insuring that Dave new
the difference.

"starman" wrote in message
...
It's an impedance matching transformer or unun. I use the word 'balun'
because most people haven't heard the term 'unun'.

CW wrote:

The word balun to describe this device, while quite common, is
incorrect. Go
he www.kc7nod.20m.com
Look for matching transformer.

"Dave" wrote in message
...
Away from the house is not possible. Even if it was, that would put
it
near
the power lines. How would I build a balun? (Websites/links?)


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"RHF" wrote in message
m...
starman wrote in message
...
Dave wrote:

I am using a DX-402 (aka Sangean ATS 505). I would be surprised if
it had a balanced antenna input, and have been thinking about just
clipping the external antenna to my whip after all. I hooked 20 feet
of 300 ohm twinlead to a 300/75 ohm transformer and miniplug last
night and plugged it in, but the signal strength was about half of
what my whip gives me. Therefore, the change in plans.

It would be a mistake to connect a good external antenna directly to the
whip. The receiver will almost certainly overload. You know the symptoms
for overloading now. If you build the low noise inverted-L, the coax can
be connected to the external antenna jack with a mini plug.

I was planning on running the vertical portion of twinlead that
went from ground level/grounding rod/coax up to the eaves over the
steel siding, but I could just as easily run the coax up the side of
the house, which would put all of the twinlead above the steel
siding. Still not "out in the open" but probably the best I can do.
Wifey doesn't want anything that obviously says "Hi there, I'm an
antenna!"

It's funny how women have an aversion to antennas. Must be an esthetic
thing. :-)

I am beginning to consider running the coax around to the end of the
house and up that side, and laying the twinlead along the ridge of the
roof from one end to the other. That would be a up a lot higher and a lot
more "out in the open."


DAVE & STARMAN,

- - - - - - - - - - This would be my recommendation - - - - - - - - -
-

The horizontal section (single wire) of an inverted-L could also run
along the roof ridge. The vertical downlead wire would connect to one
end of the horizontal section and run down the end wall of the house to
the ground. The balun would be located near the ground next to a ground
rod. The coax would go from the balun to the receiver. That's the design
of the low noise inverted-L except it's better to locate the antenna
away from the house when you can.

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

Unless you have a Target Frequency and Country (Direction)
I do not recommend Dipole Antennas for general all around
broadband 500kHz to 30MHz Shortwave Listener "SWL" Antennas.

iane ~ RHF


Gotcha. Thanks for that clarification. I do appreciate it.

Dave



No problem with the questions. It's nice to see an interesting on
topic
thread for a change.

Thanks for the encouragement. I'm not yet sure what I will end up
doing,
but I want to make the best decision possible.


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Forgot to mention, I was going to connect the conductors on the far end so
as to have a longer single line. One side of the near end would be hanging
out in space, in other words, so as not to form a loop.

Dave


"Dave" wrote in message
...
So, a matching transformer is all I need? I have pretty much decided to
use
300 ohm twinlead along the rood ridge with a 300/75 ohm matching
transformer
to connect it to the coax, and more as needed between the coax and radio.
Will that honestly work?

Thanks,

Dave


"starman" wrote in message
...
It's an impedance matching transformer or unun. I use the word 'balun'
because most people haven't heard the term 'unun'.

CW wrote:

The word balun to describe this device, while quite common, is
incorrect. Go
he www.kc7nod.20m.com
Look for matching transformer.

"Dave" wrote in message
...
Away from the house is not possible. Even if it was, that would put
it
near
the power lines. How would I build a balun? (Websites/links?)


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-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

Dave wrote:

So, a matching transformer is all I need? I have pretty much decided to use
300 ohm twinlead along the rood ridge with a 300/75 ohm matching transformer
to connect it to the coax, and more as needed between the coax and radio.
Will that honestly work?

Thanks,

Dave

A 300/50 ohm transformer is the most common type for a shortwave folded
dipole. You can still use 75-ohm coax to the 50-ohm side of the
transformer. There would be a slight impedance mismatch but it's not
that important for a receiving antenna. I do not recommend using a
300/75 TV balun for this purpose because it's designed to operate at
much higher frequencies than shortwave. Remember that you *must* connect
the two wires in the ends of the twinlead together to make a folded
dipole. Otherwise the high impedance side of the matching transformer
(300-ohms) won't be the right value for the antenna. Finally, don't
expect this antenna to be great for all shortwave frequencies and
directions. We discussed why this is so in an earlier exchange.


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STARMAN,

Why Use a TV type 300 to 75 Ohm Matching Transformer with
your SWL Antenna and 'portable AM/FM/Shortwave Radio.

May I interject my opinion based on some simple observations
using both SWL/HAM Matching Transformers and the cheap TV
type 300 to 75 Ohm Matching Transformers.

ABOUT - The TV type 300 to 75 Ohm Matching Transformers a

* Easy to Find. {RadioShack, WalMart, Walgreens, Kragens, etc}

* Simple to Use. {How To - Hook-Em-Up is Self-Evident}

* Low Cost. {Under $5}

* Generally Functions well and Operates down to 5 MHz and
well above 30 MHz. (Most of the better quality ones are now
"Marked" for 5 MHz and up.)

* Provides Coverage of 'most' of the International
Shortwave Bands: 60M, 49M, 41M, 31M, 25M, 21M, 19M,
16M, 13M, and 11M. (But not 90M and 75M Bands)

* Plus 'helps' to "Attenuate" Strong AM/MW Signals
that create images in the Shortwave Bands.
{This is an Important Bonus.}

* Allows the 'direct' Connection "Hook-Up" of Low Cost
75 Ohm TV type Coax Cable as an antenna Lead-in-Line.

IMHO: For most/many 'portable' AM/FM/Shortwave Radios
using a TV type 300 to 75 Ohm Matching Transformer is
a very good alternative to a SWL/HAM Matching Transformer.
[ Value and Cost ]

iane ~ RHF
..
..
= = = starman wrote in message
= = = ...
Dave wrote:

So, a matching transformer is all I need? I have pretty much decided to use
300 ohm twinlead along the rood ridge with a 300/75 ohm matching transformer
to connect it to the coax, and more as needed between the coax and radio.
Will that honestly work?

Thanks,

Dave

A 300/50 ohm transformer is the most common type for a shortwave folded
dipole. You can still use 75-ohm coax to the 50-ohm side of the
transformer. There would be a slight impedance mismatch but it's not
that important for a receiving antenna. I do not recommend using a
300/75 TV balun for this purpose because it's designed to operate at
much higher frequencies than shortwave. Remember that you *must* connect
the two wires in the ends of the twinlead together to make a folded
dipole. Otherwise the high impedance side of the matching transformer
(300-ohms) won't be the right value for the antenna. Finally, don't
expect this antenna to be great for all shortwave frequencies and
directions. We discussed why this is so in an earlier exchange.


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Starman,

I am no longer intending to use a folded dipole, or a dipole of any kind. I
am currently planning to connect the conductors at the far end of the 300
ohm twinlead but only connect one side of the near end to the 300/75 ohm
matching transformer. Will this not work? I don't need perfection, just
reasonably good (I think.)

Thanks,

Dave


"starman" wrote in message
...
Dave wrote:

So, a matching transformer is all I need? I have pretty much decided to
use
300 ohm twinlead along the rood ridge with a 300/75 ohm matching
transformer
to connect it to the coax, and more as needed between the coax and
radio.
Will that honestly work?

Thanks,

Dave

A 300/50 ohm transformer is the most common type for a shortwave folded
dipole. You can still use 75-ohm coax to the 50-ohm side of the
transformer. There would be a slight impedance mismatch but it's not
that important for a receiving antenna. I do not recommend using a
300/75 TV balun for this purpose because it's designed to operate at
much higher frequencies than shortwave. Remember that you *must* connect
the two wires in the ends of the twinlead together to make a folded
dipole. Otherwise the high impedance side of the matching transformer
(300-ohms) won't be the right value for the antenna. Finally, don't
expect this antenna to be great for all shortwave frequencies and
directions. We discussed why this is so in an earlier exchange.


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Dave wrote:

Starman,

I am no longer intending to use a folded dipole, or a dipole of any kind. I am currently planning to connect the conductors at the far end of the 300 ohm twinlead but only connect one side of the near end to the 300/75 ohm matching transformer. Will this not work? I don't need perfection, just reasonably good (I think.)

Thanks,

Dave

So you're going to use the twinlead as if it was a single wire. In that
case, you might as well connect the two wires in the near end too. There
isn't any advantage to keeping the wires of the near end seperated.
Connect the twinlead's near end to one wire of the high impedance side
(300-ohm) of the matching transformer (balun). The other wire on the
300-ohm side should go to a ground rod, IF you're building the antenna
design on the website I gave you. Otherwise connect the remaining
300-ohm wire to the shield of the coax. This will require some kind of
adapter, if the balun has a threaded female F-connector for the coax on
the low impedance side. A standard coax inline grounding adapter (block)
would work. These are made for connecting a ground wire to the coax
shield in a TV installation. This adapter has a female F-connector on
each end and a grounding screw on the outside of the 'block'. Connect
the remaining wire on the 300-ohm side to the ground screw on the
adapter block. If you use this kind of adapter you will also need
another adapter with a male F-connector on each end to connect the
ground adapter block to the threaded female side of the balun. You might
be able to find a coax grounding adapter which has a male F-connector on
one end and a female on the other end, along with the grounding
terminal. Then you wouldn't need two adapters.

The center wire of the coax goes to the low impedance side of the balun
which is the center hole of the threaded female F-connector on the
balun. The coax shield connects to the outside threads of that
F-connector, which would also go to the ground rod from the grounding
adapter, if you're making the website antenna.

All of the above assumes you're using a standard TV balun which has a
threaded female coax F-connector for the low impedance side and two
wires (pigtails) on the high side. You should install a male F-connector
on the balun end of the coax. In the previous post I advised against
using a TV balun because it will most likely attenuate signals below
about 10-Mhz. This means the lower shortwave bands and also the regular
AM(MW) band would be somewhat weaker but this might not be a problem,
depending on what frequencies/bands you want to hear best.



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