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Question about antennas

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Anonymous
June 2, 2005 6:04:58 PM

Archived from groups: rec.audio.tech (More info?)

I have a JVC MX-J50. The FM antenna seems to be just a piece a wire. I
would like to listen to a local FM station on 90.5 MHz. This station
is hard to receive. When I touch the wire to reposition it the station
comes in clearly as soon as I let go of the wire it disappears.
Can someone patiently explain to me all that and how to get to work.
What kind of indoor antenna can I make or buy to get this station?
Thanks.

More about : question antennas

Anonymous
June 2, 2005 6:04:59 PM

Archived from groups: rec.audio.tech (More info?)

"Nathan Gutman" wrote ...
>I have a JVC MX-J50. The FM antenna seems to be just a piece a wire. I
> would like to listen to a local FM station on 90.5 MHz. This station
> is hard to receive. When I touch the wire to reposition it the station
> comes in clearly as soon as I let go of the wire it disappears.
> Can someone patiently explain to me all that and how to get to work.
> What kind of indoor antenna can I make or buy to get this station?
> Thanks.

You could experiment with just adding more wire to the
length you currently have (the equivalent of touching it).
It may be sensitive to position and orientation as FM
radio waves are pretty direcional.

Or you could Google for: DX FM antenna

("DX" is the radio abbreviation for "distance")
Anonymous
June 2, 2005 8:02:45 PM

Archived from groups: rec.audio.tech (More info?)

I found instructions to design and make a simple antenna for the
frequency I want to receive out of 300ohm twin lead-in wire. The
receiver needs a 75ohm antenna.
Do I need a matching transformer? I see that Radio Shack has one for
$3.99.
On Thu, 2 Jun 2005 07:17:37 -0700, "Richard Crowley"
<rcrowley7@xprt.net> wrote:

>"Nathan Gutman" wrote ...
>>I have a JVC MX-J50. The FM antenna seems to be just a piece a wire. I
>> would like to listen to a local FM station on 90.5 MHz. This station
>> is hard to receive. When I touch the wire to reposition it the station
>> comes in clearly as soon as I let go of the wire it disappears.
>> Can someone patiently explain to me all that and how to get to work.
>> What kind of indoor antenna can I make or buy to get this station?
>> Thanks.
>
>You could experiment with just adding more wire to the
>length you currently have (the equivalent of touching it).
>It may be sensitive to position and orientation as FM
>radio waves are pretty direcional.
>
>Or you could Google for: DX FM antenna
>
>("DX" is the radio abbreviation for "distance")
Related resources
Anonymous
June 2, 2005 8:02:46 PM

Archived from groups: rec.audio.tech (More info?)

On Thu, 02 Jun 2005 16:02:45 GMT, Nathan Gutman
<nzgutman@sbcglobal.net> wrote:

>I found instructions to design and make a simple antenna for the
>frequency I want to receive out of 300ohm twin lead-in wire. The
>receiver needs a 75ohm antenna.
>Do I need a matching transformer? I see that Radio Shack has one for
>$3.99.
>
Yes, get a transformer if the radio receiver only has a 75 ohm F
connector. Do the plans have you make this sort of diapole? That's
the antenna you want.

http://www.radioshack.com/product.asp?catalog%5Fname=CT...

This is the transformer I believe you need and are referring to:

http://www.radioshack.com/product.asp?catalog%5Fname=CT...

Gary E
--
|Gary A. Edelstein
|edelsgNO@SPAMyahoo.com.invalid (remove NO SPAM and .invalid to reply)
|"We have met the enemy and he is us." - Walt Kelly's Pogo
Anonymous
June 2, 2005 8:34:21 PM

Archived from groups: rec.audio.tech (More info?)

On Thu, 02 Jun 2005 14:04:58 GMT, Nathan Gutman
<nzgutman@sbcglobal.net> wrote:

>I have a JVC MX-J50. The FM antenna seems to be just a piece a wire. I
>would like to listen to a local FM station on 90.5 MHz. This station
>is hard to receive. When I touch the wire to reposition it the station
>comes in clearly as soon as I let go of the wire it disappears.
>Can someone patiently explain to me all that and how to get to work.
>What kind of indoor antenna can I make or buy to get this station?
>Thanks.
US FK sits (along with othe services) between TV channels 6 and 7.
Almost any VHF (2-13) TV antenna would work. I connect my FM to the
same roof antenna system as my TV (No cable or satellite in my house).

As others mentioned a DX antenna works better, especially if you have
signal reflection problems.
, _
, | \ MKA: Steve Urbach
, | )erek No JUNK in my email please
, ____|_/ragonsclaw dragonsclawJUNK@JUNKmindspring.com
, / / / Running United Devices "Cure For Cancer" Project 24/7 Have you helped? http://www.grid.org
Anonymous
June 3, 2005 1:22:59 AM

Archived from groups: rec.audio.tech (More info?)

"Nathan Gutman" <nzgutman@sbcglobal.net> wrote in message
news:f44u91l2tbab632me91n8eb9oetsc6tuq1@4ax.com...
>I have a JVC MX-J50. The FM antenna seems to be just a piece a wire. I
> would like to listen to a local FM station on 90.5 MHz. This station
> is hard to receive. When I touch the wire to reposition it the station
> comes in clearly as soon as I let go of the wire it disappears.
> Can someone patiently explain to me all that and how to get to work.
> What kind of indoor antenna can I make or buy to get this station?
> Thanks.

You can try a folded dipole antenna. These are made of twin lead and have a
T shape. They are cheap. Connect it to the 300 Ohm connectors if possible or
use a 300 to 75 Ohm transformer. If you know the general direction of the
signal, adjust the antenna so that the horizontal part of the T is
perpendicular to the signal. You may need to move the antenna around due to
multipath and shading effects.
John
Anonymous
June 3, 2005 1:23:00 AM

Archived from groups: rec.audio.tech (More info?)

Do we know what kind of antenna connector this has?
If any? It could be just a captive wire hanging out the back.
Anonymous
June 3, 2005 2:11:48 AM

Archived from groups: rec.audio.tech (More info?)

Yes, looks exactly like what I was going to make. It doesn't give the
length of the lead-in section.
According to my calculations for a 90.5mhz I need an 62" element.
Radio Shack specs say 58" element which is good for about 96.8mhz.
Do you think this will have any serious adverse effect?
On Thu, 02 Jun 2005 14:56:47 -0500, Gary A. Edelstein
<edelsgNO@SPAMyahoo.com.invalid> wrote:

>On Thu, 02 Jun 2005 16:02:45 GMT, Nathan Gutman
><nzgutman@sbcglobal.net> wrote:
>
>>I found instructions to design and make a simple antenna for the
>>frequency I want to receive out of 300ohm twin lead-in wire. The
>>receiver needs a 75ohm antenna.
>>Do I need a matching transformer? I see that Radio Shack has one for
>>$3.99.
>>
>Yes, get a transformer if the radio receiver only has a 75 ohm F
>connector. Do the plans have you make this sort of diapole? That's
>the antenna you want.
>
>http://www.radioshack.com/product.asp?catalog%5Fname=CT...
>
>This is the transformer I believe you need and are referring to:
>
>http://www.radioshack.com/product.asp?catalog%5Fname=CT...
>
>Gary E
Anonymous
June 3, 2005 2:24:55 AM

Archived from groups: rec.audio.tech (More info?)

In article <9mcu91d86iqijb8p2c8epckqcrbop9h2nj@4ax.com>,
Steve Urbach <dragonsclaw@NOTmindspring.com> wrote:

> On Thu, 02 Jun 2005 14:04:58 GMT, Nathan Gutman
> <nzgutman@sbcglobal.net> wrote:
>
> >I have a JVC MX-J50. The FM antenna seems to be just a piece a wire. I
> >would like to listen to a local FM station on 90.5 MHz. This station
> >is hard to receive. When I touch the wire to reposition it the station
> >comes in clearly as soon as I let go of the wire it disappears.
> >Can someone patiently explain to me all that and how to get to work.
> >What kind of indoor antenna can I make or buy to get this station?
> >Thanks.
> US FK sits (along with othe services) between TV channels 6 and 7.
> Almost any VHF (2-13) TV antenna would work.

Not necesarily true. There's a "third harmonic" relationship between
channels 2-6 and channels 7-13 that makes it attractive to design
antennas that do just fine for all the VHF TV channels while being
rather insensitive to the 88-108 MHz FM band.

You can always try an existing TV antenna to see how well it works, but
if you're buying new, it's possible to find ones specifically designed
to include the FM frequencies.

Isaac
Anonymous
June 3, 2005 3:49:57 AM

Archived from groups: rec.audio.tech (More info?)

There are two connections: one labeled FM 75ohm and the other is
"ground". Right now I have a single wire about 10 feet long hanging
from the FM 75ohm connection. I manipulated that wire to be able to
hear the 90.5mhz station but the reception is very poor.
On Thu, 2 Jun 2005 16:23:41 -0700, "Richard Crowley"
<richard.7.crowley@intel.com> wrote:

>Do we know what kind of antenna connector this has?
>If any? It could be just a captive wire hanging out the back.
>
Anonymous
June 3, 2005 3:49:58 AM

Archived from groups: rec.audio.tech (More info?)

"Nathan Gutman" wrote ...
> There are two connections: one labeled FM 75ohm and the other is
> "ground". Right now I have a single wire about 10 feet long hanging
> from the FM 75ohm connection. I manipulated that wire to be able to
> hear the 90.5mhz station but the reception is very poor.

1) Try just making the wire longer and experiment with moving it
around. You just get lucky for little or no cost.

2) Get an "FM antenna" from any number of places. Radio Shack
sells dozens of different things, most of which would likely
improve your reception.

Of course if we knew the power, terrain and distance, it would
be easier to recommend something more appropriate. What are
the call-letters of the station? Where are you? (City & State)
June 3, 2005 5:45:25 AM

Archived from groups: rec.audio.tech (More info?)

As a good make-it-yourself antenna, try a 30-inch piece of wire, straight
up. Or possibly oriented some other way.
Anonymous
June 3, 2005 3:30:22 PM

Archived from groups: rec.audio.tech (More info?)

Nathan Gutman <nzgutman@sbcglobal.net> writes:

> I have a JVC MX-J50. The FM antenna seems to be just a piece a wire. I
> would like to listen to a local FM station on 90.5 MHz. This station
> is hard to receive. When I touch the wire to reposition it the station
> comes in clearly as soon as I let go of the wire it disappears.

When you touch the antenna, your presence there has considerable
effect on the antenna operation, and when you let go that effect
dissappears. The effect that you can have to the antenna is
chage it's tuning by the your capacitance, you acting as extra
part of antenna picking more signal or you acting as some
kind of reflector that reflects more signal to antenna..
Dpending your position, reeivign conditions and antenna design
you touchign the antenna can make th reception consierably
worse or better.

> Can someone patiently explain to me all that and how to get to work.
> What kind of indoor antenna can I make or buy to get this station?


The FM dipole antenna is economical and relatively simple to install,
whilst offering a considerable increase in reception quality compared
to "just a piece of wire" antennas. You just hang this kind of
dipole to your wall or window, etc..

The best quality FM radio receiver system for weak stations
consists of a directional FM antenna, permanently erected externally
and pointing to the FM station transmitter you want to listen to.
This kind of FM antenna is very much like a VHF television antenna,
just sligtly different in the constrution (optimized for FM band
operation instead of TV channel frequencies).


Some links on the topics:

FM Antennas
http://www.abc.net.au/reception/radio/fm_antenna.htm

FM Dipole for 88-108 MHz
http://www.northcountryradio.com/Articles/fmdip.htm

AXIS 7945 FM Dipole Antenna
http://electrogalaxy.dtopinc.com/index.html?object=an85...

FM DIPOLE ANTENNA
http://www.ecreso.com/uk/docs/D_DLBFM5_uk.pdf


--
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at
http://www.epanorama.net/
Anonymous
June 3, 2005 9:02:47 PM

Archived from groups: rec.audio.tech (More info?)

On Thu, 02 Jun 2005 22:11:48 GMT, Nathan Gutman
<nzgutman@sbcglobal.net> wrote:

>Yes, looks exactly like what I was going to make. It doesn't give the
>length of the lead-in section.
>According to my calculations for a 90.5mhz I need an 62" element.
>Radio Shack specs say 58" element which is good for about 96.8mhz.
>Do you think this will have any serious adverse effect?
>
I doubt it. Go for it.

Gary E
--
|Gary A. Edelstein
|edelsgNO@SPAMyahoo.com.invalid (remove NO SPAM and .invalid to reply)
|"We have met the enemy and he is us." - Walt Kelly's Pogo
Anonymous
June 4, 2005 4:17:48 AM

Archived from groups: rec.audio.tech (More info?)

On Thu, 2 Jun 2005 18:51:33 -0700, "Richard Crowley"
<rcrowley7@xprt.net> wrote:

>"Nathan Gutman" wrote ...
>> There are two connections: one labeled FM 75ohm and the other is
>> "ground". Right now I have a single wire about 10 feet long hanging
>> from the FM 75ohm connection. I manipulated that wire to be able to
>> hear the 90.5mhz station but the reception is very poor.
>
>1) Try just making the wire longer and experiment with moving it
>around. You just get lucky for little or no cost.
I moved the wire around incredibly through a doorway, around a wall
and the reception is good. If I move portion of the wire just a few
inches I lose the reception. Incredible!
>
>2) Get an "FM antenna" from any number of places. Radio Shack
>sells dozens of different things, most of which would likely
>improve your reception.
>
>Of course if we knew the power, terrain and distance, it would
>be easier to recommend something more appropriate. What are
>the call-letters of the station? Where are you? (City & State)

The station is an NPR station WPKT and I am in Simsbury, CT. It's
website says that their signal is supposed to be strong here.
June 4, 2005 4:34:31 AM

Archived from groups: rec.audio.tech (More info?)

> The station is an NPR station WPKT and I am in Simsbury, CT. It's
> website says that their signal is supposed to be strong here.

Most NPR stations have rather low power. Also, there can be "dead spots" in
any city or building.
Anonymous
June 4, 2005 5:21:11 AM

Archived from groups: rec.audio.tech (More info?)

On Sat, 04 Jun 2005 00:17:48 GMT, Nathan Gutman
<nzgutman@sbcglobal.net> wrote:

>On Thu, 2 Jun 2005 18:51:33 -0700, "Richard Crowley"
><rcrowley7@xprt.net> wrote:
>
>>"Nathan Gutman" wrote ...
>>> There are two connections: one labeled FM 75ohm and the other is
>>> "ground". Right now I have a single wire about 10 feet long hanging
>>> from the FM 75ohm connection. I manipulated that wire to be able to
>>> hear the 90.5mhz station but the reception is very poor.
>>
>>1) Try just making the wire longer and experiment with moving it
>>around. You just get lucky for little or no cost.
>I moved the wire around incredibly through a doorway, around a wall
>and the reception is good. If I move portion of the wire just a few
>inches I lose the reception. Incredible!
>>
>>2) Get an "FM antenna" from any number of places. Radio Shack
>>sells dozens of different things, most of which would likely
>>improve your reception.
>>
>>Of course if we knew the power, terrain and distance, it would
>>be easier to recommend something more appropriate. What are
>>the call-letters of the station? Where are you? (City & State)
>
>The station is an NPR station WPKT and I am in Simsbury, CT. It's
>website says that their signal is supposed to be strong here.
Building insulation with foil attenuates and also reflects signals.
There is a chance of finding the perfect WRONG place inside :/ 

Outdoor antennas have a better chance of suppling a better signal
unless you live in a concrete (and iron) jungle.

, _
, | \ MKA: Steve Urbach
, | )erek No JUNK in my email please
, ____|_/ragonsclaw dragonsclawJUNK@JUNKmindspring.com
, / / / Running United Devices "Cure For Cancer" Project 24/7 Have you helped? http://www.grid.org
!