Even if you do match it, it will be at only one frequency. At any other, the
mismatch returns.

"-=jd=-" wrote in message
...
I had about 300' of #14 insulated wire strung in this "Z" shape down one
of the woodlines on my property. It really overloaded the receiver, but
with an external attenuator, it was a very useable signal snagger.

Last week, the new wore off and I decided to change it. I now have about
100' of that wire arranged in horizontal triangular loop.

The happy surprise is that the S/N ratio is much, much better.

The one thing that I would like to do is try to figure out the actual
characteristic impedance of the antenna. I've found information that shows
me how to do this with a noise-bridge, but I don't have one of those.

I was wondering if anyone knows of a link or a formula for finding a
relatively close "ballpark" figure for characteristic impedance. I'm
thinking there isn't (without the inclusion of one or more physical
measurements) due to all of the variables involved.

To add to the dificulty, the antenna is over sloping terrain and I recall
that height above terrain affects impedance.

The end goal is to match a coax feed to the antenna as closely as
*reasonably* possible. I understand that there's the distinct possibility
that after going through all the effort to determine what ratio is needed
for the transformer, a SWAG may well have produced the same or similar
results... But, it's a hobby and I have the time.

-=jd=-
--
My Current Disposable Email:

(Remove YOUR HAT to reply directly)

CW wrote:

Even if you do match it, it will be at only one frequency. At any other, the
mismatch returns.

There are ways to get more of a broadband match, via the use of a matching
transformer.



"-=jd=-" wrote in message
...
I had about 300' of #14 insulated wire strung in this "Z" shape down one
of the woodlines on my property. It really overloaded the receiver, but
with an external attenuator, it was a very useable signal snagger.

Last week, the new wore off and I decided to change it. I now have about
100' of that wire arranged in horizontal triangular loop.

The happy surprise is that the S/N ratio is much, much better.

The one thing that I would like to do is try to figure out the actual
characteristic impedance of the antenna. I've found information that shows
me how to do this with a noise-bridge, but I don't have one of those.

I was wondering if anyone knows of a link or a formula for finding a
relatively close "ballpark" figure for characteristic impedance. I'm
thinking there isn't (without the inclusion of one or more physical
measurements) due to all of the variables involved.

To add to the dificulty, the antenna is over sloping terrain and I recall
that height above terrain affects impedance.

The end goal is to match a coax feed to the antenna as closely as
*reasonably* possible. I understand that there's the distinct possibility
that after going through all the effort to determine what ratio is needed
for the transformer, a SWAG may well have produced the same or similar
results... But, it's a hobby and I have the time.

-=jd=-
--
My Current Disposable Email:

(Remove YOUR HAT to reply directly)

Steve, if i were to mount something like that,
and bring it to the radio by coax; how would
this be grounded for static and lighting?
i would rather ground outside and not at the
radio...thanks...
Drifter...

Drifter wrote:

Steve, if i were to mount something like that,
and bring it to the radio by coax; how would
this be grounded for static and lighting?
i would rather ground outside and not at the
radio...thanks...

You can do it several different ways. Here, I use the type of
transformer that utilises a ground at the feed point. Hence, the antenna
itself is always at DC ground.

It's simply a matter of how one connects the windings. It's certainly
possible to short the one end of the winding to the coax connector, and
then just get away with a ground at the receiver.

I believe this is the method that the RF Systems MLB balun uses. Myself,
I prefer to have a ground at the feed point.

From the feed point here it's about 9' down to an 8' or so ground rod.

I also have a separate ground for the receiver(s), and I would still
recommend it's use.

I used to offer them for sale, and could build one any way the customer
wanted. It's time consuming to make them though so I jut drifted away
from it. Last time I wound one up was for a fellow in Ireland a couple
years ago, and he has good success with it. I think I sold about 275 of
them, but I just could not keep up.

If you have other questions I'll try and help you out. I'm much better
at explaining in person and if I have some exhibits to use!

Steve
Holland, MI
Drake R7, R8 and R8B

http://www.iserv.net/~n8kdv/dxpage.htm

just re-read you web page. good info by the way. also
looked at the 20m site. 9-1 seems to be the way to go.
i 'll try making one of these. don't have the junk box
i had as a youngster, (had my ticket in the 50's). used
my Dad's radios, never had my own set-up and never seemed
to get the time to get back into it. after my wife died, i
moved farther into the country. quiet out here. and, i got
about an acre here, should be lots of room to run wire.
i had looked at an alpha-delta. thought i'd try to brew
my own. been using a an-lp1 here. want to get outside now.
picked up 2 RS long wires and stranded 18 for a song and
a danced at a local winter fest. Breezshooters fest next
month, should find the rest of parts and a mini box. will
give it a go. i feel 55 is still young enough to fall off
a roof. you recommend long wire or something like an
inverted V? thanks a lot Steve...
Drifer...

Drifter wrote:

just re-read you web page. good info by the way. also
looked at the 20m site. 9-1 seems to be the way to go.
i 'll try making one of these. don't have the junk box
i had as a youngster, (had my ticket in the 50's). used
my Dad's radios, never had my own set-up and never seemed
to get the time to get back into it. after my wife died, i
moved farther into the country. quiet out here. and, i got
about an acre here, should be lots of room to run wire.
i had looked at an alpha-delta. thought i'd try to brew
my own. been using a an-lp1 here. want to get outside now.
picked up 2 RS long wires and stranded 18 for a song and
a danced at a local winter fest. Breezshooters fest next
month, should find the rest of parts and a mini box. will
give it a go. i feel 55 is still young enough to fall off
a roof. you recommend long wire or something like an
inverted V? thanks a lot Steve...
Drifer...

I've found that around 70' or so works pretty well for all 'round use.
Start going longer and the antenna starts to get more directional with
respect to the direction the wire is running.

Gotta go! The boomers are moving in again!

http://www.weatherunderground.com/ra...olland%2c%20MI

Steve
Holland, MI
Drake R7, R8 and R8B

http://www.iserv.net/~n8kdv/dxpage.htm

thanks Steve...
Drifter...

Take a look on my website. www.kc7nod.20m.com

"Drifter" wrote in message
...
Steve, if i were to mount something like that,
and bring it to the radio by coax; how would
this be grounded for static and lighting?
i would rather ground outside and not at the
radio...thanks...
Drifter...

Drifter schrieb:

Steve, if i were to mount something like that,
and bring it to the radio by coax; how would
this be grounded for static and lighting?
i would rather ground outside and not at the
radio...thanks...
Drifter...

Be aware that grounding does not save your radio from a lightning shock
hitting your antenna. It will for some chance only prevent to burn down
your house. ALL electronical stuff in your house may be dead then.

If done right is does.

"Volker Tonn" wrote in message
...


Drifter schrieb:

Steve, if i were to mount something like that,
and bring it to the radio by coax; how would
this be grounded for static and lighting?
i would rather ground outside and not at the
radio...thanks...
Drifter...

Be aware that grounding does not save your radio from a lightning shock
hitting your antenna. It will for some chance only prevent to burn down
your house. ALL electronical stuff in your house may be dead then.