Antenna Ground

Antenna Ground

Post by Jeffrey Donohu » Tue, 25 Feb 1997 04:00:00

I just bought a DX-394. This unit has a grounding terminal on the back. I
have grounded it to a cold water pipe.
Now, when I run my outside antenna to the radio and connnect it to the RCA
type jack, should I ground the antenna as well?

I currently have the antenna hooked up to a 1/8 inch miniplug, and I have
this grounded. If I can find one at radio schack, I may just buy an adapter
so I don't have to cut the miniplug off. I would like to be able to easily
switch the antenna between the 394 and my Sangean 909.
--
Jeffrey Donohue

 
 
 

Antenna Ground

Post by Dan Grunbe » Tue, 25 Feb 1997 04:00:00




>I just bought a DX-394. This unit has a grounding terminal on the back. I
>have grounded it to a cold water pipe.
>Now, when I run my outside antenna to the radio and connnect it to the RCA
>type jack, should I ground the antenna as well?

>I currently have the antenna hooked up to a 1/8 inch miniplug, and I have
>this grounded. If I can find one at radio schack, I may just buy an adapter
>so I don't have to cut the miniplug off. I would like to be able to easily
>switch the antenna between the 394 and my Sangean 909.
>--
>Jeffrey Donohue


This discussion is from the point of view of reception only.  The legal
requirements for protecting your antenna from lightning strikes can be
determined by calling your local building inspector's office.  

Grounding the RADIO is an excellent idea.  Ground is a part of every
antenna system.  Your antenna's signal will find a path to return
to ground, one way or another.  For instance, the ground path of a
typical inexpensive AM portable radio, operating on the fourth floor of
a house might be via capacitive coupling to whatever nearby wiring (the
AC-line's ground wire for example) is connected to ground.  Perhaps
you've noticed that sometimes, you can increase the effect of the
capacitive path to ground enough, just by holding the radio in your
hand, to increase the readability of a weak station.  By providing a
more efficinet wired ground path for your SW receiver, often you can
increase signal readability more reliably (and more comfortably <g>)
than you might by holding onto your receiver.  

It is true that grounding the antenna itself is a good precautionary
measure WHEN YOU AREN'T USING THE ANTENNA.  Grounding the antenna will
give your house and your equipment some measure of protection against
static electrical build up and nearby (but not too nearby <g>) lightning
strikes.  However, grounding the antenna while your using it will
drain away some/most/all of the received signal (depending on where on
the antenna the ground connection is made) to ground rather than to your
receiver.  

BOTTOM LINE

Ground the receiver.

Ground the antenna when you're not using it, or if the antenna was
specifically DESIGNED to be grounded.
--

Daniel Grunberg                     Kensington MD  USA

 
 
 

Antenna Ground

Post by David Rickme » Wed, 26 Feb 1997 04:00:00


>If you have longwire antenna, go ahead and terminate (ground) the end.
>You should be a reduction in noise and the antenna will become more
>directive.

Don't you ground it through a 600-1000 Ohm resistor at the far end to
make it more unidirectional?
dr
 
 
 

Antenna Ground

Post by BobForre » Mon, 03 Mar 1997 04:00:00



Quote:>However, grounding the antenna while your using it will
>drain away some/most/all of the received signal

The original question referred to a mini plug and did not describe the
antenna or cable arrangment. If the antenna is correctly fed by a coaxial
cable, you can ground the shield of the cable or the radio and get similar
results. Grounding the shield offers advantages with respect to lightning
protection. I would not have an unshielded cable running into my house.

The simplest lightning protection is to always remove the antenna from the
radio when not in use. I keep mine in a mayonaise jar with a cover on the
cable that shorts the shield to the center conductor. You can also wire
the cable cover neon bulb that flashes with each static pulse. I also
never use the antenna when storm conditions are nearby, or during high
wind, espcially the dry cold winter winds that can generate large static
discharges.

There are devices (available from most any ham radio store) that will
discharge the static built up on your antenna line and also give you a
***for attaching a ground line.

If your antenna is a single wire with a single wire feedline, consider
replacing the feedline with coax and a stactic discharge device. You could
attach the static discharge block to a wall, with single wire feed going
up to the antenna, and coax (and a ground wire) going down.

Bob Forrester NS3Z