On 11/06/2010 7:43 PM, Radiomatt wrote:
Krypsis wrote:

The FM band is 88 - 108 MHz.

Hold on, young fella. That depends where in the world you are. Japan
uses 76–90 MHz, and the OIRT band in Eastern Europe is 65.8–74 MHz. It's
only the rest of the world that uses 88-108 MHz!

OK, then use the calculator on this website to readjust your figures if
you live or intend to live in those regions.

http://www.1728.com/freqwave.htm

88 - 108 is the most common. You will also note that my example of
100MHz is not exactly the centre of that spectrum but, for the purposes
of the exercise, close enough.

Krypsis

On Jun 10, 4:01*pm, bpnjensen wrote:
On Jun 10, 12:55*pm, Twitchell wrote:

I've seen some car radio whip antennas that look like they have a wire wrapped
around them. *The wraps are not close but lazily spiral down the length of the
antenna.

Does this help reception? *Is the coil attached somehow to the car or just the
antenna itself?

twitch

My antenna on my minivan is like that.

I think the supporting whip is fiberglas/or some insulating material,
and the wire is the actual electrical element; and in the interest of
saving length and providing strength, they wrap the wire around the
slightly shorter antenna pole. *The wire is then connected to the lead
of the antenna. *It works fine, about as good as a metal whip of
similar length. *Antennas for cars are pretty uncomplicated
critters... :-)

I can't believe I have never seen that before. Wouldn't there be a
chance for eventually the wire to work itself free, is it glued or
clipped to the whip?

On Jun 10, 2:27*pm, Gregg wrote:
On Jun 10, 4:01*pm, bpnjensen wrote:





On Jun 10, 12:55*pm, Twitchell wrote:

I've seen some car radio whip antennas that look like they have a wire wrapped
around them. *The wraps are not close but lazily spiral down the length of the
antenna.

Does this help reception? *Is the coil attached somehow to the car or just the
antenna itself?

twitch

My antenna on my minivan is like that.

I think the supporting whip is fiberglas/or some insulating material,
and the wire is the actual electrical element; and in the interest of
saving length and providing strength, they wrap the wire around the
slightly shorter antenna pole. *The wire is then connected to the lead
of the antenna. *It works fine, about as good as a metal whip of
similar length. *Antennas for cars are pretty uncomplicated
critters... :-)

I can't believe I have never seen that before. Wouldn't there be a
chance for eventually the wire to work itself free, is it glued or
clipped to the whip?- Hide quoted text -

- Show quoted text -

Picture a thin pole (the whip) with a very gently coiled wrap of wire,
a turn every inch or so, from top to bottom. Then, the entire thing
is covered with a wrap of something like shrink-wrap to hold it
altogether. Unless the antenna is traumatized, the wire is pretty
much set for life.

On Jun 10, 5:58*pm, bpnjensen wrote:
On Jun 10, 2:27*pm, Gregg wrote:





On Jun 10, 4:01*pm, bpnjensen wrote:

On Jun 10, 12:55*pm, Twitchell wrote:

I've seen some car radio whip antennas that look like they have a wire wrapped
around them. *The wraps are not close but lazily spiral down the length of the
antenna.

Does this help reception? *Is the coil attached somehow to the car or just the
antenna itself?

twitch

My antenna on my minivan is like that.

I think the supporting whip is fiberglas/or some insulating material,
and the wire is the actual electrical element; and in the interest of
saving length and providing strength, they wrap the wire around the
slightly shorter antenna pole. *The wire is then connected to the lead
of the antenna. *It works fine, about as good as a metal whip of
similar length. *Antennas for cars are pretty uncomplicated
critters... :-)

I can't believe I have never seen that before. Wouldn't there be a
chance for eventually the wire to work itself free, is it glued or
clipped to the whip?- Hide quoted text -

- Show quoted text -

Picture a thin pole (the whip) with a very gently coiled wrap of wire,
a turn every inch or so, from top to bottom. *Then, the entire thing
is covered with a wrap of something like shrink-wrap to hold it
altogether. *Unless the antenna is traumatized, the wire is pretty
much set for life.- Hide quoted text -

- Show quoted text -

Yeah OK, you didn't mention that is was encased, I thought it was
flowing freely in the wind, my post above mentioned what you just
said. ;-)

"bpnjensen" wrote in message
...
On Jun 10, 12:55 pm, Twitchell wrote:
I've seen some car radio whip antennas that look like they have a wire
wrapped
around them. The wraps are not close but lazily spiral down the length of
the
antenna.

Does this help reception? Is the coil attached somehow to the car or just
the
antenna itself?

twitch

My antenna on my minivan is like that.

I think the supporting whip is fiberglas/or some insulating material,
and the wire is the actual electrical element; and in the interest of
saving length and providing strength, they wrap the wire around the
slightly shorter antenna pole. The wire is then connected to the lead
of the antenna. It works fine, about as good as a metal whip of
similar length. Antennas for cars are pretty uncomplicated
critters... :-)

Car antennas my be simple critters, but the coax used is special.
Mike

On Jun 10, 3:55*pm, Twitchell wrote:
I've seen some car radio whip antennas that look like they have a wire wrapped
around them. *The wraps are not close but lazily spiral down the length of the
antenna.

Does this help reception? *Is the coil attached somehow to the car or just the
antenna itself?

twitch

Hmm, I've never seen that. I have seen the radio whips that have wire
around them but they are then encased in plastic, like some CB
antennas are.

In article ,
Gregg says...

On Jun 10, 3:55=A0pm, Twitchell wrote:
I've seen some car radio whip antennas that look like they have a wire wr=
apped
around them. =A0The wraps are not close but lazily spiral down the length=
of the
antenna.

Does this help reception? =A0Is the coil attached somehow to the car or j=
ust the
antenna itself?

twitch

Hmm, I've never seen that. I have seen the radio whips that have wire
around them but they are then encased in plastic, like some CB
antennas are.

That's what I'm talking about...they're encased (sometimes) in plastic.

Gregg wrote:


Hmm, I've never seen that. I have seen the radio whips that have wire
around them but they are then encased in plastic, like some CB
antennas are.

On a Firestick, the wire is real.

On Jun 11, 9:44*am, dave wrote:
Gregg wrote:

Hmm, I've never seen that. I have seen the radio whips that have wire
around them but they are then encased in plastic, like some CB
antennas are.

On a Firestick, the wire is real.

I know that.

In message
,
Gregg writes
On Jun 11, 9:44*am, dave wrote:
Gregg wrote:

Hmm, I've never seen that. I have seen the radio whips that have wire
around them but they are then encased in plastic, like some CB
antennas are.

On a Firestick, the wire is real.

I know that.

I once made a helically compressed 80m halfwave dipole by winding each
leg of around 66' of PVC insulated wire on 33' of the type plastic line
used for rotary clothlines/airers (making sure, of course, that the
inner core was nylon, and not steel).

I marked the line every 6", and the wire every 1'. After a few false
starts, I soon got the knack of getting the spacing of the turns
correct. I suppose that diameter of the line was around 1/8", and I
needed to space the turns at around 3/8".

Obviously, I had dipole consisting of 132' of wire, but I have no idea
whether the turns were close enough to make a significant increase in
the inductance per unit length, thereby loading the antenna, and making
it electrically longer than a halfwave.

I only used the antenna once, at a scout 'Jamboree on the Air' event. I
put it up as an inverted V, with the centre at about 30', and the ends
at 20'. I used 300 ohm feeder. It was very sharply tuned (using a
balanced Z-match tuner). Daytime conditions on 80m were not very good,
but the antenna seemed particularly poor. I think I only managed a
couple of contacts, with only S5 reports where I would have expected
s9+.

40m was a bit better but, at the end of the day, just before we packed
up, things seemed distinctly lively on 20m. I got a 59 from 350 miles
away and, surprisingly, another from 40 miles (extremely short skip
conditions, it appeared, which may have explained the poor conditions on
80m).

I haven't bothered to try the antenna again. I have no idea if it was
working OK on 80m, and the poor performance was simply poor conditions.
I've still got it somewhere, so maybe one day, I'll get around to it.
--
Ian