Return to KLUBNL.PL main page

rsgb_lf_group
[Top] [All Lists]
<prev [Date] next>
[Advanced]
 <prev [Thread] next>

Re: LF: Lost current in a coil

from [Dick Rollema] [Permanent Link][Original]
To: [email protected]
Subject: Re: LF: Lost current in a coil
From: Dick Rollema <[email protected]>
Date: Wed, 02 Mar 2005 16:43:46 +0100
In-reply-to: <4225CA7F.15619.BBCBA7@localhost>
References: <4225CA7F.15619.BBCBA7@localhost>
Reply-to: [email protected]
Sender: [email protected]
To Mike and All

At 15:15 2-3-05, G3XDV wrote:
A useful test to see whether radiation causes the loss, would be to
completely screen the loading coil.
Because the size of the coil is so small, expressed in wavelength,  radiation is negligible.

I have never understood why, if the current is thought to stay the
same from top to bottom of a coil, the voltage is much bigger at the
top? Is this a phase thing?

The voltage at the bottom is equal to the output voltage of the transmitter; at e.g. 100W this is 70V over 50 ohm.

As an example let the inductance of the coil  be 5mH. Then its reactance at 136kHz is 4270 ohm.
With an aerial current of for instance 2A flowing through the coil the voltage at the top of the coil will be
2 * 4270 = 8541V higher than at the bottom. 
So total voltage at the top will be 70 + 8541 = 8610V.

73, Dick, PA0SE
[More with this subject...]
<Prev in Thread] Current Thread [Next in Thread>
Previous by Date:  LF: Lost current in a coil, Mike Dennison
Next by Date:  Re: LF: Lost current in a coil, Rik Strobbe
Previous by Thread:  LF: Lost current in a coil, Mike Dennison
Next by Thread:  Re: LF: Lost current in a coil, Rik Strobbe
Indexes:  [Date] [Thread] [Top] [All Lists]