What Antenna for Short Wave

[Michael A. Terrell]

GregS wrote:

In article <V5udnRT6OM_05hXUnZ2dnUVZ_uednZ2d@earthlink.com>, "Michael A. Terrell" <mike.terrell@earthlink.net> wrote:

letterman@invalid.com wrote:

OK, now we have two conflicting sources of information. Aside from
trying both of them and seeing which works better I am not sure
whether to ground it or not ?????
I would have thought this would be an established fact !


news:rec.radio.amateur.antenna would be the right newsgroup for your
questions.



I don't agree. Its a Ham newsgroup.

How about rec.radio.shortwave

The last time I went there it was >90% trolls but if that's where you
want to go, I don't care.


--
http://improve-usenet.org/index.html

aioe.org, Goggle Groups, and Web TV users must request to be white
listed, or I will not see your messages.

If you have broadband, your ISP may have a NNTP news server included in
your account: http://www.usenettools.net/ISP.htm


There are two kinds of people on this earth:
The crazy, and the insane.
The first sign of insanity is denying that you're crazy.

 

On Tue, 03 Feb 2009 12:17:59 -0500, Van Chocstraw
<boobooililililil@roadrunner.com> wrote:

letterman@invalid.com wrote:
I just bought a portable AM-FM-SW radio. It picks up pretty well on
all bands, but I live in a metal house and know I am losing signal
because of it. In fact I took the radio outdoors and got much better
reception. The radio just has a single telescoping antenna that comes
up to about 30 inches. I want to add an outdoor antenna for the
shortwave. I was told that any piece of wire strung from the house to
a pole would help. I can only clip it onto the telescoping antenna
since there is no antenna connector on the radio, so I'd just use an
alligator clip. My question is what the ideal length of the wire
should be, or don't it matter? OR maybe it should be as long as I can
make it? Also, does height matter? Or does the location matter, such
as going east, north, or .....

Please advise me.

Thanks

LM


I thought short wave radio was dead. Internet radio has far more to offer.

Internet radio does not work on a dialup account like I have. Living
in the country, we're lucky to have dialup. Until 2001 there was no
internet at all unless it was a long distance call.

 

[Dave]

"GregS" <zekfrivo@zekfrivolous.com> wrote in message
news:gm9tmb$jpa$3@usenet01.srv.cis.pitt.edu...

In article <ptmdnen5qMK36BXUnZ2dnUVZ_qfinZ2d@posted.internetamerica>,
"Dave" <db5151@hotmail.com> wrote:

letterman@invalid.com> wrote in message
news:insfo490h8tn7172vuvoqg5ru74rk8bbu1@4ax.com...
On Tue, 3 Feb 2009 01:50:42 -0000, "Arfa Daily"
arfa.daily@ntlworld.com> wrote:


"Engineer" <junk2007@rogers.com> wrote in message
news:07a737ae-cbb0-45af-ad72-d558fe929217@g1g2000pra.googlegroups.com...
On Jan 30, 7:23 pm, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:
letter...@invalid.com> wrote in message

news:f5v6o4hbs14o02c8m40ggfq9s144i5l6p0@4ax.com...

(snip)

You might not need (or in fact want) to make a direct physical
connection
to
the telescopic antenna. Experiment with just wrapping a few turns of
the
(still insulated) end of the wire around the telescopic. You can also
try
grounding the end of the wire, and then wrapping a few turns around
the
telescopic.

(snip)

No, don't ground anything. Any coil around the metal telescopic
antenna is effectively shorted by the metal "core" (a single shorted
turn - read transformer theory.) If you ground the end you short out
all the antenna signal. If you leave it ungrounded you have decent
capacitive coupling that works.
But if you take a few turns around a true antenna coil (to make a
primary coil) you will couple some signal into the radio - but this is
generally too much trouble. Better, connect the antenna via a 100 pF
capacitor to the telescopic antenna.
Cheers,
Roger

There are many references on the 'net to 'inductively' coupling an
external
long wire antenna to a telescopic, by either wrapping turns directly
around
the telescopic, and grounding the 'free' end, or by wrapping the turns
around a tube, also with the free end grounded, and then sliding the
tube
over the telescopic, the latter method claiming to allow a certain
amount
of
'adjustment' to the degree of coupling, to prevent strong signals
overloading the front end, and giving rise to all manner of intermod
products.

Arfa


OK, now we have two conflicting sources of information. Aside from
trying both of them and seeing which works better I am not sure
whether to ground it or not ?????
I would have thought this would be an established fact !


I personally have a (roughly) 110 foot random wire antenna hiding under
the
edges of the ridgevent on my house, and it is only grounded in the sense
that the shield of the coax between it and my radio is attached to a
couple
of 10 foot copper-plated ground rods driven into the ground. The "signal"
line (wire antenna and center conductor of the coax) are not attached to
ground anywhere, as this would indeed kill any signal intended for the
input
of the radio. And the coax comes in my wndow and terminates in a "male"
plug, to which I attach an alligator clip that goes to a foot or so of
(insulated) wire that I coil around my (closed) whip antenna. And this
works great. Note that I only use the coax to shield the signal line
against EMI from the A/C that all of this has to go past to get to my
window. The shield to that coax is grounded where line comes off of the
roof, and again where it comes in my window. At the random-wire end, the
shield is unconnected, and the center conductor of the coax is soldered to
the 110 feet of wire. Also, if you directy connect the wire antenna to
your
whip, I believe you may eventually have trouble from static discharge
building up from wind blowing across the wire. Note that I said "I
believe", as I do not actually *know* this to be a fact. But that is why
I
put a static discharge circuit into the RF amplifier that I built to
enhance
weak signals.

My $.02. Hope that perhaps it helps...

Shortwave Dave


In any case a static discharge device would be very NICE to have.
We used to use Blitz Bugs on antennas. I don't know what the rating
was. There are probably other low capcitance devices that can be used to
drain
a charge, even a high value resistor will drain a charge to ground without
affecting the antenna. Having an outside "spark plug" to ground would make
me happier.

greg

Check out alt.binaries.schematics.electronic for my recent posting of the
static-discharge circuit I use on my RF amplifier for shortwave. Also
protects against nearby lightening strikes (see previous post on 1/31/09 on
the topic of single wire shortave antennas."

Dave