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Re: [TowerTalk] tuners and power rating

To: towertalk@contesting.com
Subject: Re: [TowerTalk] tuners and power rating
From: Steve Hunt <steve@karinya.net>
Date: Wed, 01 Dec 2010 12:43:51 +0000
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Jim,

I disagree!

If we restrict ourselves to talking about the series-form complex load 
impedance, the reactive component will *not* affect the current required 
through the load for a particular power dissipation. For example, to 
dissipate 150W in a load of 150+j0 you need a current of 1A; you also 
need the same 1A if you want to dissipate 150W in a load of 150+j1000.

Once you start talking about parallel components, things are different. 
Your example of a 150 Ohm resistor in parallel with a 150 Ohm inductor 
represents a load of 75+j75 Ohms - the resistive part is no longer 150 Ohms.

73,
Steve G3TXQ



On 01/12/2010 04:14, jimlux wrote:
>
> The current could be higher or lower.  Say you've got a 150 ohm resistor
> in parallel with a 150 ohm inductor.  The current that flows through the
> inductor also flows through the feedline, and contributes to the loss.
>
> Or, if you've got the resistor and inductor in series.  Now the current
> flow will be even less. (by a factor of 70%).
>
> that's the difference between apparent power (Irms * Vrms) and active
> and reactive power.
>
>
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