Using speaker wire for a dipole
 

On 8/3/2011 4:48 PM, Irv Finkleman wrote:
Hear! Hear!

I would have been off the air forever if this newsgroup had been
my only source of knowledge. I would have been afraid!
What I didn't know about Jx and SWR didn't make any difference -- I was on
the air and really enjoying the hobby! I didn't even know how to solder
then!

Right.

But I would like to say that it isn't at all that the information is
wrong. In fact, the experts are generally 100 percent right. And that is
where some of the problems are.

A noob comes in, and gets 3 different answers, and becomes hopelessly
confused because they would seem to contradict each other. They don't
really know how to figure it out.

It isn't confined to this group. Another group I'm in where I am a bit
of an expert, Amateur telescope making, some times suffers from the same
thing.

My point is that I'm not trying to chide the experts. After all, it's
not very graceful to bust peoples chops when they take the time to
answer a question. I's more begging them to realize that I'm a bit of an
idiot, and easily confused!

- 73 de Mike N3LI -

Using speaker wire for a dipole
 

"Irv Finkleman" wrote in message
...

snip

After 50 plus years of hamming fun, I have come to the conclusion that
anything with a little metal in it will serve as an antenna if you hook it
up in the right manner.


Yes.

I have properly-built 6m jpole which terminates in my shack. If I
disconnect the coax from the 6m rig, the connector center pin fits nicely
into the LONG WIRE terminal on my HF tuner. Electrically, the antenna is
merely a 13' hunk of metal, untuned as far as HF is concerned, except after
a little tuner knobulation. It's not the equal of a 'proper" antenna, but
it works.

Using speaker wire for a dipole
 

On 8/2/2011 3:14 AM, wrote:
Stainless steel mig welding wire. Any reason why this won't work as a
wire antenna? Very strong, fairly cheap, but doesn't like kinks.
'I personally think Ray Davies wrote some very good songs.'

http://en.wikipedia.org/wiki/Ray_Davies



SS is a terrible conductor?

I've seen copper clad MIG wire

The real issue is either you're putting that antenna up for the ages, in
which case the NEC (aka NFPA 70) rules are a good sizing guideline; or,
you're putting it up expecting it to fall down sooner or later, in which
case you might as use whatever wire is convenient. For a lot of folks,
buying a 500 foot spool of solid AWG14 wire at the hardware store is a
good compromise.

The real issue is paying attention to "what happens when the wire
breaks" so that you don't wind up inadvertently connecting the 14.4kV MV
distribution line to your hand via the feedline and rig.

Using speaker wire for a dipole
 

On 8/2/2011 8:24 AM, John S wrote:
On 8/1/2011 7:52 PM, Jim Lux wrote:
On 7/31/2011 3:26 PM, Owen Duffy wrote:
John wrote in :


Maybe because NFPA 70 costs $150 US?


Yes, standards are expensive things and it is a frustration when
researching.

Anyway, NFPA makes recommendation on the wires for ham antennas
specifically, and it may be binding in some places.

I suspect the reason for ignoring it is that the advice is unaccepable
to most hams.

That said, it does seem over the top in some areas, and is hardly
comprehensive in its thinking. For example, the prescription for
feedlines seems to not be aware of the existence and use of coax.

You refer to the "continuously enclosed metallic shield", I suspect.


I guess it is these gaps that give critics the basis for arguing against
the whole thing.

Anyway, in respect of antenna wires, it does not 'permit' annealled
copper or other low strength materials, and it 'requires' a minimum
conductor diameter of #14 for up to 150' span.

They may have had in mind the risk to persons and property where low
strength conductor are broken in high wind and make contact with power
lines.


That is precisely why. (ice loads, too)

NFPA (according to what you posted) requires heavier gauge wire for
transmitting than for receiving. Transmitting makes the wire weigh more?


An interesting observation. You'd have to go look at the history of
that article in the code to find out why. It's not impossible that they
were following standard commercial installation practice/recommendations
back in the day, and it was "acceptable power loss" related. (the wire
sizing for AC branch circuits is based on tolerating a 2% voltage drop,
not overheating of the conductor)

Using speaker wire for a dipole
 

On 8/2/2011 12:24 PM, Sal wrote:
wrote in message ...
On 1 Aug,
This replaces one which failed a couple of years ago constructed with
thin insulated 5A lighting flex not much more than bell wire that had been
up
nearly 30 years.

This got me thinking. (Dangerous, yes, but I occasionally risk it.)

Since a normal dipole has current max near the center, is there more
localized heating (I-squared-R) nearer the feed point? Seems like it ought
to be. Can you overheat a small wire and make it fail there by melting?????

No, I don't want to try it. I'm hoping somebody knows. Exciting story even
better.

"Sal"



Fusing current is remarkably high for small conductors in free air, even
for 100% duty cycle.

AWG30 (0.01" diameter) = about 10 Amps (Preece equation)

Scales as 1.5 power..
so, going to AWG 20 (.0316") - about 50 amps..

Considering an inverted V dipole with feedpoint Z of 50 ohms, at 1kW,
the current is about 5 amps...

So running that legal limit amp with a brick on the key to your AWG30
stealth antenna won't melt it. (it probably will get pretty warm.. and
corona at the ends might be spectacular)

Using speaker wire for a dipole
 

On 8/2/2011 4:42 PM, Tom Horne wrote:
On 8/1/2011 20:42, Jim Lux wrote:
On 7/31/2011 2:02 PM, Owen Duffy wrote:


PS: hams universally ignore the guidance of NFPA 70 which makes
recommendation on conductors for antennas.

Are you saying the electrical code is sort of like the pirate code? more
guidelines than actual requirements?

I think the way that hams can rationalize it is that most wire antennas
(particularly those made with fine wire) are, by their nature,
"temporary installations". The finer the wire, the more temporary.

The National Electric Code limits the use of Temporary installations to
power and lighting conductors.

"ARTICLE 527 Temporary Installations
527.1 Scope.
The provisions of this article apply to temporary electrical power and
lighting installations." Copyright 2002 the National Fire Protection
Association.

--
Tom Horne, W3TDH


I was thinking more of local codes or enforcement. After all, the local
"Authority Having Jurisdiction" (AHJ in code-speak) can and does
override the NEC all the time.

There are also a whole lot of other "installations of a temporary
nature" in the code: check out the sections about theatrical and motion
picture filming. They allow substantially higher currents for a given
size wire, on the not unreasonable basis that they're being operated
under the (hopefully) continuous supervision of qualified personnel.

Using speaker wire for a dipole
 

"Jim Lux" wrote in message
...

Fusing current is remarkably high for small conductors in free air, even
for 100% duty cycle.

AWG30 (0.01" diameter) = about 10 Amps (Preece equation)

Scales as 1.5 power..
so, going to AWG 20 (.0316") - about 50 amps..

Considering an inverted V dipole with feedpoint Z of 50 ohms, at 1kW, the
current is about 5 amps...

So running that legal limit amp with a brick on the key to your AWG30
stealth antenna won't melt it. (it probably will get pretty warm.. and
corona at the ends might be spectacular)


Thank you very much. It's exactly what I was wondering about.

"Sal"

Using speaker wire for a dipole
 

On Aug 1, 6:32*am, KD2AIP wrote:
Anyone have experience making a dipole from 18 gauge speaker wire? *I
have a whole lot of it lying around the house, and was wondering if I
could put it to some good use.

Well, not sure what gauge wire it is, but I've been using cheap
speakerwire for HF dipoles with no problems whatsoever. Not certain,
but I think this is the stuff I use he

http://www.jaycar.com.au/productView...SUBCATID=992#1

My prime HF antenna started out as a coax-fed 40m half-wave (10m/leg)
dipole made of this stuff in an inverted-V configuration. I used a
home made 1:1 voltage balun at the feed point. Over time, I moved the
feed point to near the back of the tuner with a short 3in length of
coax, and ran a random length of 300ohm ribbon to the feed point of
the dipole.

Later after reading about the G5RV, I extended each leg to 16m long.
It is important to note that while similar to a G5RV, my antenna does
not feature the same length of ribbon as a G5RV. The antenna is not
mounted up high, the apex would be at gutter level (we have a two-
storey house here). Legs tie off no higher than 2m in the air. One
end ties off to a frangipannie (sp?) tree in our front yard, the other
to a piece of rope running to a macadamia tree in our back yard. I
have a feeling the frangipannie is helping form part of the antenna.

This antenna, while quite deaf I find on the 10m band, has worked into
VK5 on 15m, I have had contacts into ZL on 20m, and it works quite
well locally on 40m and 80m. I have had successful contacts using QRP
power levels on 80m with this antenna, and it is very easy to tune
there.

It has broken once or twice. It has never taken me any longer than
about 15 minutes to repair and get back up in the air. It's also
cheap enough to consider being disposable, should disaster truly
strike.

So I say, go for it … it might as well do something useful.

Regards,
Stuart VK4MSL

Using speaker wire for a dipole
 

A local job lot store was selling 100' rolls of #18 speaker wire. I bought as many as I could. I use it for not only hf antennas, but am making open wire line with discarded Bic pens as separators (there was an article in QST about this). I have had a lot of success with this.

Using speaker wire for a dipole
 

On 8/12/2011 8:30 PM, wrote:


I use it for not only hf antennas, but am
making open wire line with discarded Bic pens as separators (there
was an article in QST about this).

That has to be a lot of old pens.

- 73 de Mike N3LI -