Amps
[Top] [All Lists]

Re: [Amps] Measuring RF Power

To: garyschafer@comcast.net
Subject: Re: [Amps] Measuring RF Power
From: R.Measures <r@somis.org>
Date: Wed, 23 Mar 2005 03:58:26 -0800
List-post: <mailto:amps@contesting.com>
On Mar 22, 2005, at 11:18 AM, Gary Schafer wrote:

>
>
> R.Measures wrote:
>> On Mar 22, 2005, at 8:16 AM, Gary Schafer wrote:
>>>
>>> ... ... ...
> 1. How much peak power do you get when you have 10 volts peak across a 
> 50 ohm resistor?
> @ 2 watts.

Agreed
>
> 2. What is the average power across that resistor?
> @ 1 watt.  (average power = 1/2 peak power)

The question is indeterminate unless the waveform is stated.
>
> 3. If you find the RMS voltage of that 10 volts peak that = 7.07 volts.

Not unless the waveform is stated.   For example, the RMS potential of 
a square-wave is not .707 of E-pk.

>    What do you get when you find power from the RMS voltage?
> @ 1 watt.
>
> Why would the one watt be average power in one case and RMS power in 
> the other ?


PEP measurement as used for SSB does not indicate the average power 
delivered to the load, instead, it is the RMS value of the power 
delivered at the instant of the crest of modulation.
>
> 73
> Gary  K4FMX
>
>
>
>

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org

_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps

<Prev in Thread] Current Thread [Next in Thread>