There has been, and will always be hot debates over the best and or
safest
way to ground an radio and antenna system.
While I do not have enough room for a beverage, the "isolation"
technque
from this web page helped knock the local QRM down to make listening
much more enjoyable. I have my isolation transformer mounted outside
my
"radio" room. I did not use the resistive matching pads.
My antenna is about 60 feet and runs from wouth east to north west,
with
the feed point on the south-east end. I have an 8 foot ground rod at
the
base of a fairly tall tree and the antenna is tied off at about 15
feet off
the ground and runs to another tree where it is about 25 up. I use a
9:1 matching transformer at the base of the tree with the coax
grounded to the ground rod.
At the house end a 1:1 transformer is mounted in a metal box with the
incoming shield connected to a gas discharge protective device mounted
to
the case which is then grounded. The coax braid will be grounded if
the
voltage exceeds about 150V. The added stray capacitance did not effect
the noise level. But grounding the briad bumps the noise lee by everal
S units
on my R2000. The output side of the 1:1 transformer has one side
grounded.
This helps to keep noise from my desk top PC out of the received
signals.
You can wind your own transformers and there are many sites that offer
directions on a 9:1 antenna, (check out Joh Doty's ideas) and the 1:1
can be made with the same type core used for the 9:1, just with
anywhere from 10 to
30 turns per side. I tried several different turns and it did not
effect
the received levels to any noticable degree. I went with store bought
transformers because of size issues. I wanted to build the boxes as
small as possible. My antenna is designed be nearly invisible.
I have a mini patch bay with all the incoming antennas, this "long"
wire, an
HF active antenna and a VHF/UHF scanner antenna, and all the radio's
antenna
inputs so I can easily connect any antenna to any radio. I choose BNC
because
I got a great deal on a buch of Amp BNC females and solder male
connectorc.
They are mounted on a grounded right angle piece of alumium about 14"
long.
I use short jumpers to route the antenna to the desired radio. It
sounds a lot fancier then it it really is. I would love to have the
money to spring for decent RF Relays to allow rorting by throwing athe
right switch.
I use a MiniCirucits ZFSC-2-1 "power divider" to split the incoming HF
signal so that I can feed it to my R2000 and my DX398. While this
splitter is rated for 5~500MHz, it passes NDBs with no significant
attenuation. I also use this spllter to allow two VHF/UHF scanners to
work from the same scanner antenna.

This web site is not mine, I found it several years ago and found the
ideas presented to be useful.
Check it out at:
http://members.aol.com/WA1ION/nrants.pdf

On 11 Mar 2004 15:11:15 -0800, (Terry) wrote:

There has been, and will always be hot debates over the best and or
safest
way to ground an radio and antenna system.
While I do not have enough room for a beverage, the "isolation"
technque
from this web page helped knock the local QRM down to make listening
much more enjoyable. I have my isolation transformer mounted outside
my
"radio" room. I did not use the resistive matching pads.

If you'd like to experiment with REALLY low-noise antenna systems,
might I suggest you build a simple receiving loop for the desired band
or bands you wish to listen to. A good receiving loop antenna will
blow the doors off a longwire. Here are a few articles and some
experience to help you get started. Even someone in an apartment can
have super receiving antennas!

http://www.qsl.net/kc2tx/
http://pages.zdnet.com/radio_k7zb/id14.html
http://members.aol.com/articles4lf/bploop.pdf
http://members.fortunecity.com/xe1bef/loop.htm
http://www.hard-core-dx.com/nordicdx/antenna/loop/
(If you use hula hoops, buy your own, not use your kids')
http://www.angelfire.com/md/k3ky/page45.html

Just like the loop antenna in your AM table radios, you can NULL OUT
that damned insulator down the street or your neighbor's livingroom
lamp dimmers with a loop....(c;



Larry W4CSC
POWER is our friend!

(Larry W4CSC) wrote in message ...
On 11 Mar 2004 15:11:15 -0800, (Terry) wrote:

There has been, and will always be hot debates over the best and or
safest
way to ground an radio and antenna system.
While I do not have enough room for a beverage, the "isolation"
technque
from this web page helped knock the local QRM down to make listening
much more enjoyable. I have my isolation transformer mounted outside
my
"radio" room. I did not use the resistive matching pads.

If you'd like to experiment with REALLY low-noise antenna systems,
might I suggest you build a simple receiving loop for the desired band
or bands you wish to listen to. A good receiving loop antenna will
blow the doors off a longwire. Here are a few articles and some
experience to help you get started. Even someone in an apartment can
have super receiving antennas!

http://www.qsl.net/kc2tx/
http://pages.zdnet.com/radio_k7zb/id14.html
http://members.aol.com/articles4lf/bploop.pdf
http://members.fortunecity.com/xe1bef/loop.htm
http://www.hard-core-dx.com/nordicdx/antenna/loop/
(If you use hula hoops, buy your own, not use your kids')
http://www.angelfire.com/md/k3ky/page45.html

Just like the loop antenna in your AM table radios, you can NULL OUT
that damned insulator down the street or your neighbor's livingroom
lamp dimmers with a loop....(c;



Larry W4CSC
POWER is our friend!

The only problem with all of the loops that I am familiar with is the
need to tune the loop for the frequency of interest. Since I listen
from below 200KHz to 20MHz, it is difficult to do this with commonly
available parts. The advantage of a "long" wire antenna is the wide
frequency range with no tunning.
I have a VLF loop for listening to "whistlers" and other ELF events.
And a McKay Dymek loop for MW. Perhaps someday I will be able to
affoard to build a remote loop, that covers the 3 decades from 100KHZ
trrhough 20MHz.
I have dreamed of a remote loop, with servos to allow it to be rotated
and tilted from the radio position. It is clearly "do-able", but not
by me.
Terry