For a moderatly complete study of twisted pair ingress/egress see:

http://www.comsoc.org/sac/private/2002/june/pdf/20jsac05-stolle.pdf#search='twisted%20pair%20ingress'

Get those calulators out.

Please note that this studies much higher levels of "RF" then the
typical SW receiver will be
"see". So what is acceptable for a networking or telco environment, may
not be acceptable
for a receiving use.

A comparison betweent the details int his link and the coax link:
http://www.tennadyne.com/pdf/coaxial_tenn.pdf
could be educational.

Or maybe not, after all some people still insist the world is flat.....

Enjoy!

Terry

wrote in message
Or maybe not, after all some people still insist the world is flat.....
or twisted...
Good stuff, Terry.

Tom

R2000SW & TH,

The World is a Cork-Screw and the Universe is . . .
a Bottle of Wine - Drink-Up ! ) ~ RHF

In article ,
"Tom Holden" wrote:

wrote in message
Or maybe not, after all some people still insist the world is flat.....
or twisted...
Good stuff, Terry.

Twisted pair or coax are just engineering solutions to a problem. Both
have their place depending on what you want to accomplish, money spent,
et cetera.

--
Telamon
Ventura, California

Telamon wrote:
In article ,
"Tom Holden" wrote:

wrote in message
Or maybe not, after all some people still insist the world is flat.....
or twisted...
Good stuff, Terry.

Twisted pair or coax are just engineering solutions to a problem. Both
have their place depending on what you want to accomplish, money spent,
et cetera.

--
Telamon
Ventura, California
++++++++++++++++++++++++
I wasn't trying say that coax is always "better" then twisted, but
after the 150
nonesense posts on the subject I wanted to dump some reality based math

on the subject.

As I have pointed out before in this NG, even coax can suffer from
ingress.
It just has a lot less then any balanced line I have experimented with.

I use balanced audio, video, data and networking, lines everyday at
work and
at home. But for low level RF distribution I have found that coax,
triax or twinax
beats any sort of balanced line when it comes to keeping iterference
out.

I still wish the proponenets on both sides would just string ~100' of
each type
line out, terminate properly, couple to the receiver properly, ie use a
transformer
to convert the balanced to unbalanced, and see which has the most
"stary" signal
pickup.

I want to do every thing I can to make sure that my 1uV signal from my
antenna
doesn't get smoothered in crud before it gets into my receiver. I get
enough crud
from the electronic crap that surrounds me.

Terry

On 3 Dec 2005 19:10:06 -0800, wrote:


David wrote:

The R-390A has a Twinax RF Input.
-------------------------------------
And the R-390 also has the Twinax input.

I have had much better sucess feeding it with coax.

There is a simple mod to allow an unbalanced connection
that is maybe 10dB more sensitive.

Terry

I used a CATV BalUn for mine. Note: The Unbalanced input bypasses the
preselector.

Telamon wrote:

You hit on the main problem I think most people have and that is the
local noise problem wether it is picked up by the antenna or lead-in as
the determining factor to hearing a station or not.


Here, it's usually downstream in the audio section. I can hear the
incessant 'When are you taking the garbage out' even now. It's quite
disruptive.



mike

David wrote:
On 3 Dec 2005 19:10:06 -0800, wrote:


David wrote:

The R-390A has a Twinax RF Input.
-------------------------------------
And the R-390 also has the Twinax input.

I have had much better sucess feeding it with coax.

There is a simple mod to allow an unbalanced connection
that is maybe 10dB more sensitive.

Terry

I used a CATV BalUn for mine. Note: The Unbalanced input bypasses the
preselector.
-----------------------------------------
A friend uses this scheme:http://www.r390a.com/html/feedpoint.html

I use a 7 turn primary to 10 turn, CT to ground, secondary.
I tried many different combinaitons and this appears to give the best
overall response.

The difference is minimal.

I own a R-391, synchro motor drive, and my friend has a R-390A.
In side by side tests it is difficult to impossible to tell which
recever is active.

It is cool enough to use the R-390 and my cats love to sleep on top of
the
receiver.

Terry

On 4 Dec 2005 08:23:25 -0800, wrote:


David wrote:
On 3 Dec 2005 19:10:06 -0800, wrote:


David wrote:

The R-390A has a Twinax RF Input.
-------------------------------------
And the R-390 also has the Twinax input.

I have had much better sucess feeding it with coax.

There is a simple mod to allow an unbalanced connection
that is maybe 10dB more sensitive.

Terry

I used a CATV BalUn for mine. Note: The Unbalanced input bypasses the
preselector.
-----------------------------------------
A friend uses this scheme:http://www.r390a.com/html/feedpoint.html

I use a 7 turn primary to 10 turn, CT to ground, secondary.
I tried many different combinaitons and this appears to give the best
overall response.

The difference is minimal.

I own a R-391, synchro motor drive, and my friend has a R-390A.
In side by side tests it is difficult to impossible to tell which
recever is active.

It is cool enough to use the R-390 and my cats love to sleep on top of
the
receiver.

Terry

I sold mine when I moved into SoCal Edison area at 14 cents a KWH.
Was fun in HL&P country at 6 cents a KWH. Also had the Dual IF
version of theRacal RA-17, quite possibly a better receiver than the
R-39X series.

On 3 Dec 2005 17:09:19 -0800, wrote:


wrote:
How about using twisted wire inside the coax cables?
cuhulin
---------------------------------------------
Twinax is a balanced pair in side a coaxial shield.
I haven't ever seen a true twisted pair inside a braid.


Twinax is used for balanced video and some instrumentation connections.

Standard on IBM AS/400s.



Another varient of coax is triax. Think of normal coax with another
braid
over the coaxial pvc jacket. Can acheive decade more of isolation.
Commonly usd for very long, up to ~1/3mile professinal mobile video
runs.

I use Triax to feed a Doty style transformer located about 25' up.
The outer shield is the low side of the Hi-Z winding and connects to
it's own ground system.

Terry


Terry