On 8 Jun, 11:20, Richard Clark wrote:
On Fri, 08 Jun 2007 06:27:13 GMT, Owen Duffy wrote:
If so, are they relevant to rating the wire for current handling capacity
at RF where for example skin effect increases the dissipation for a given
current?

Hi Owen,

Really, a 1mm wire is sufficient for a 100W transmitter in a long wire
antenna application. There is no need to elaborate.

73's
Richard Clark, KB7QHC

Sorry Owen, you have been censored.

John Smith I wrote:
Anyone know how many amps commonly flow through a current node on a 1/4
or 1/2 wave ant? Now, that's the real question, isn't it?

John, you should be talking about the current anti-node,
i.e. the current maximum, not the current node (minimum).
For a 1/2WL center-fed dipole or a 1/4WL monopole, the
current is maximum at the feedpoint which is easy to
calculate, e.g. 1.414 amps for 100 watts into 50 ohms.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:

...
calculate, e.g. 1.414 amps for 100 watts into 50 ohms.

Cecil:

Then, since E = I*R, 70.7 volts ... thanks.

Still, I like my 1/4 copper tubing, silver would be better ...

Regards,
JS

Then, since E = I*R, 70.7 volts ... thanks.

But on the other ends where there could be 6000 ohms the current is
low (0.13 A) but the voltage is around 775 V.

Andrea
IZ2LSC

Andrea wrote:
Then, since E = I*R, 70.7 volts ... thanks.

But on the other ends where there could be 6000 ohms the current is
low (0.13 A) but the voltage is around 775 V.

Andrea
IZ2LSC


Exactly, tape a ne-2 bulb on the antenna, will light when you xmit ...

JS

the answer makes prefect sense professor!

On Jun 8, 12:00 pm, art wrote:
On 8 Jun, 11:20, Richard Clark wrote:

On Fri, 08 Jun 2007 06:27:13 GMT, Owen Duffy wrote:
If so, are they relevant to rating the wire for current handling capacity
at RF where for example skin effect increases the dissipation for a given
current?

Hi Owen,

Really, a 1mm wire is sufficient for a 100W transmitter in a long wire
antenna application. There is no need to elaborate.

73's
Richard Clark, KB7QHC

Sorry Owen, you have been censored.

Andrea wrote in news:1181394846.390221.30080
@c77g2000hse.googlegroups.com:


Then, since E = I*R, 70.7 volts ... thanks.

But on the other ends where there could be 6000 ohms the current is
low (0.13 A) but the voltage is around 775 V.

Something tells me we're going to end up with tapered wires here
pretty soon... ;^)

One more thing is not clear to me:
If I use a 1/4 wave wire, where are the 6000 ohms?
Near the feed point or on the far end?

Thanks

Andrea
IZ2LSC


On Jun 9, 11:44 pm, Mike Coslo wrote:
Andrea wrote in news:1181394846.390221.30080
@c77g2000hse.googlegroups.com:



Then, since E = I*R, 70.7 volts ... thanks.

But on the other ends where there could be 6000 ohms the current is
low (0.13 A) but the voltage is around 775 V.

Something tells me we're going to end up with tapered wires here
pretty soon... ;^)

On Mon, 11 Jun 2007 08:34:06 -0000, Andrea wrote:

One more thing is not clear to me:
If I use a 1/4 wave wire, where are the 6000 ohms?
Near the feed point or on the far end?

Hi Andrea,

At the far end. Think of the antenna as a resonant transmission line
(meaning it is not terminated in its characteristic Z) and that hi
impedance at the end is transformed through the length to the lower 30
- 50 Ohms typically encountered (accumulating real resistances of the
wire and radiation resistance along the way).

73's
Richard Clark, KB7QHC

Andrea wrote in news:1181550846.846262.75560
@m36g2000hse.googlegroups.com:

One more thing is not clear to me:
If I use a 1/4 wave wire, where are the 6000 ohms?
Near the feed point or on the far end?


It will be at the far end of the antenna, Andrea.

- 73 de Mike KB3EIA -