slinky beverage
the captain
at this web site. any suggestions before I plop down at the drafting table ?
N8KDV
the captain wrote:
> the captain is thinking about a slinky beverage using the super slinky
> at this web site. any suggestions before I plop down at the drafting table ?
What's wrong with wire?
Joe Strain
My indoor slinky serves my dx 398 real well on 31 M 19M even down to 80M if
the stations are out'a the "mud"
Yodar
===============
"N8KDV" <n8...@nospam.iserv.net> wrote in message
the captain
wire. it's time for new adventures.
N8KDV
the captain wrote:
> the captain sails new and unexplored waters, most people already use
> wire. it's time for new adventures.
Well if you intend to make a Beverage antenna with slinkys you'd better be
prepared to buy a bunch of em.
the captain
puppies. 4000 feet, now that be an antenna !
RHF
> the captain wrote:
>
> > the captain is thinking about a slinky beverage using the super slinky
> > at this web site. any suggestions before I plop down at the drafting table ?
>
> What's wrong with wire?
>
It's All in a Name - The SLINKY is a "Metal Toy"
> >
> >
> > http://www.metaltoys.com/Slinky.htm
yachtboy!
Let me know how well it works, Ill post the results on my Slinky page.
==========
"Being diabetic is alot like having an un-invited
guest at a picnic, who keeps pointing out the potato
salad may have gone bad."--W.B. Willis
"Destiny has a strange sense of humor..." K. Honeycutt
----------
http://www.geocities.com/swl_yb400pe
http://www.geocities.com/swl_yb400pe/psychedelic.htm
http://www.geocities.com/swl_yb400pe/slinkypage.html
"He not busy being born is busy dying..." B. Dylan
=======================
Gregg
I had one - worked awesome!
Get the electrolytic coated ones - they won't rust.
--
Gregg
*Perhaps it's useful, even if it can't be SPICE'd*
Visit the GeeK Zone - http://geek.scorpiorising.ca
John Doty
"the captain" <cap...@captain.com> wrote:
It won't work as a Beverage. The trick to a Beverage is that the TEM mode
trapped on the wire moves at the same speed as the incoming waves, so even
the weak longitudinal coupling due to ground absorption builds up. The
wave on the wire stays in phase with a signal coming from the direction
the wire is pointed.
A Slinky is a "slow wave" structure: the speed of the trapped mode is much
less than the vacuum speed of light. The phase relationship that makes a
Beverage work won't hold.
--
| John Doty "You can't confuse me, that's my job."
| Home: j...@w-d.org
| Work: j...@space.mit.edu
snow
area and it made for excellant reception on the mediumwave AM band. I used
an Icom 735. I pulled in the carribean some from Maine, and stations in
middle America...stuff I could not do without the 500 foot wire. It seems
the longer the better for mediumwave as it picks up the ground wave signal.
the captain <cap...@captain.com> wrote in message
news:lwO_a.98739$3o3.6...@bgtnsc05-news.ops.worldnet.att.net...
Jake Brodsky
wrote:
>the captain sails new and unexplored waters, most people already use
>wire. it's time for new adventures.
The "captain" has no idea what he's doing. This ain't no beverage
you're making. I'm not saying you won't hear some interesting things
with it, but it won't have the properties a real Beverage with plain
wire would have.
73,
Jake Brodsky, AB3A mailto:fru...@erols.com
"Beware of the massive impossible!"
the captain
yours is the only opinion I would trust
would a slinky make a good travel antenna ? take it to the park or
camping and stretch it out? seems like it would be quick to put away and
to set up.
the captain
english from this thread
the big C
Frank Dresser
> hey bud, "ain't" is not proper english. there could be children learning
> english from this thread
>
> the big C
>
>
Ain't's almost OK with the good folk at dictionary.com:
"Even educated and upper-class speakers see no substitute in folksy
expressions such as Say it ain't so and You ain't seen nothin' yet."
http://dictionary.reference.com/search?q=ain%27t
Too bad the online version of the OED is a subscription service. I'm sure
they'd have even more to say about this fine colloquialism.
Frank Dresser
John Doty
<cap...@captain.com>.101637$0v4.7...@bgtnsc04-news.ops.worldnet.att.net>,
"the captain" <cap...@captain.com> wrote:
> would a slinky make a good travel antenna ? take it to the park or
> camping and stretch it out? seems like it would be quick to put away and
Well, what I use is a dipole made with a pair of 3 meter lengths of wire
connected to a plug. The wires have alligator clips at the ends, mostly
just as a handy way to string them up, but I also sometimes clip them to
available metal objects. It's not hard to coil up.
The Slinky is fun, but calculations of its performance relative to a
straight wire are discouraging. Below resonance it's just a hunk of wire,
only slightly better than a straight wire of similar length. It's a
relatively efficient antenna at resonance (which for a "standard" slinky
is around 7 MHz), but above resonance it is less efficient than a straight
wire of the same length. For HF reception, efficiency generally matters
most at the higher frequencies where the Slinky's efficiency is in
decline.
RHF
"It's a relatively efficient antenna at resonance (which for a
"standard" slinky is around 7 MHz)"
So what would you think the relative 'resonant frequency' of the small
diameter and shorter Slinky Jr. be ? ? ?
~ RHF
.
.
= = = "John Doty" <j...@w-d.org>
= = = wrote in message news:<mpidnanT7N9...@speakeasy.net>...
John Doty
rhf-...@pacbell.net wrote:
> So what would you think the relative 'resonant frequency' of the small
> diameter and shorter Slinky Jr. be ? ? ?
One of the peculiar things about a small diameter helix is that over a
rather wide range of pitch angles and diameters it resonates at
approximately twice twice the frequency that it would if it were
stretched out straight.
RHF
> In article <e5e13af8.03081...@posting.google.com>,
> rhf-...@pacbell.net wrote:
>
> > So what would you think the relative 'resonant frequency' of the small
> > diameter and shorter Slinky Jr. be ? ? ?
>
> One of the peculiar things about a small diameter helix is that over a
> rather wide range of pitch angles and diameters it resonates at
> approximately twice twice the frequency that it would if it were
> stretched out straight.
>
JD,
So basically, Measure the Diameter and Count the Number of Turns in
the Slinky. Use these two numbers to calculate the length of the wire
(flat metal strip) used to make the Slinky. Take that Length in Feet
to use the Full Wavelength Antenna Formula to determine the
Theoretical Frequency and Double that for the Apparent/Resonate
Frequency of the Slinky.
My 3 Pack of "Metal Springs" (Mini-Slinkys) Toys
- - From the Dollar Tree (99 Cent) Store.
* Outside Diameter = 1 1/8 Inch
* Pie = 3.14
* Number of Turns = 100
= = = 353.25 Inches = 29 Feet 5.5 Inches
Formula: FWL / MHz = Feet (1005 / MHz = 29.4375)
This Slinky's Theoretical Frequency would be 34.140 MHz
Then the Apparent/Resonate Frequency of this Slinky would be 68.280
MHz
I guess that one of these Mini-Slinkys, alone will not work to well
for a SWL Antenna. Although it does Stretch-Out (8FT) nicely from
Ceiling to Floor as an Indoor Vertical Antenna (Missing Broomstick
Antenna).
But a pair of these Mini-Slinkys, set-up as a Half Wave Dipole Antenna
using a 300 Ohm Twin Lead FeedLine would have an Apparent/Resonate
Frequency of 16.713 MHz.
Enough of my ramblings ~ RHF
.
.
Telamon
"John Doty" <j...@w-d.org> wrote:
> In article <e5e13af8.03081...@posting.google.com>,
> rhf-...@pacbell.net wrote:
>
> > So what would you think the relative 'resonant frequency' of the small
> > diameter and shorter Slinky Jr. be ? ? ?
>
> One of the peculiar things about a small diameter helix is that over a
> rather wide range of pitch angles and diameters it resonates at
> approximately twice twice the frequency that it would if it were
> stretched out straight.
Looking at it from the lumped element perspective you increase the
parasitic capacitance of the wire by making it into a helix. This
capacitance over its length reduces its inductive value, which causes
its electrical length to be shorter.
3 dimensionally the helix will just look like a shorter piece of metal
to a far field. This is because the physical length of the wire in free
space is shorter as a radiating element. In other words you raise the
frequency in which the wire is an efficient radiator by making it into a
helix.
--
Telamon
Ventura, California
starman
>
> In article <e5e13af8.03081...@posting.google.com>,
> rhf-...@pacbell.net wrote:
>
> > So what would you think the relative 'resonant frequency' of the small
> > diameter and shorter Slinky Jr. be ? ? ?
>
> One of the peculiar things about a small diameter helix is that over a
> rather wide range of pitch angles and diameters it resonates at
> approximately twice twice the frequency that it would if it were
> stretched out straight.
Is there a formula that applies to a Slinky?
-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
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Frank Dresser
"starman" <sta...@tech.net> wrote in message
news:3F52D4F8...@tech.net...
>
> Is there a formula that applies to a Slinky?
>
>
I suppose you could try the solonoid3 program from Reg Edward's selelection.
Among other things, it calculates the self resonant frequency of solonoid
coils.
http://www.btinternet.com/~g4fgq.regp/page3.html#S301"
Frank Dresser
Telamon
wrote:
> John Doty wrote:
> >
> > In article <e5e13af8.03081...@posting.google.com>,
> > rhf-...@pacbell.net wrote:
> >
> > > So what would you think the relative 'resonant frequency' of the small
> > > diameter and shorter Slinky Jr. be ? ? ?
> >
> > One of the peculiar things about a small diameter helix is that over a
> > rather wide range of pitch angles and diameters it resonates at
> > approximately twice twice the frequency that it would if it were
> > stretched out straight.
>
> Is there a formula that applies to a Slinky?
Not hard to calculate this with a helix of at least three turns will
result in an impedance of ~ 140 ohms:
Wavelength = WL
Diameter of a turn .35 WL
Circumference of a turn 1.1 WL
Pitch ~ 13.5 deg
Spacing between turns WL tan 13.5 deg (about 1.35 WL)
Seen from the side the helix should look like a sine wave proportional
to the size of an EM wave it is made for in air. From this you can
probably guess how it works.
A typical slinky would work in the microwave range.
I consider the helix to be a basic antenna in that it emulates the way a
wave travels in space. A reference dipole is like space terminated to a
passing wave.
--
Telamon
Ventura, California