[Elecraft] KPA-500 "Output for Input" schedule?

[Gary Gregory]

Stan,

Allow some variation to antenna variations also.

This on 15M, swr is 1.0:1

2W = 30W out
2.5W = 40W
3w = 50w
3.5w = 60w
4w = 70w
4.5w = 75w out
5w = 80w
5.5w  = 90w
6w = 100w
6.5w = 110w
7w = 120w
7.5w = 130w
8w = 150w
8.5w = 160w
9w = 170w
9.5w = 180w
10w = 190w
11w = 200w
12w = 225w

NOTE to ALL: This was not done with lab equipment or even a dummy load. This
was measured  using a K3 and a tri-band yagi and a cw tone.

Gary

On 12 May 2011 07:13, Al Lorona <alorona at sbcglobal.net> wrote:

> It's very easy to measure the 1-tone gain compression characteristics of an
> amplifier. The desired result is a graph of Pout vs. Pin, with Pin on the
> horizontal axis and Pout on the vertical.
>
> So what one needs to do is set Pin to the amp, and measure Pout into a
> dummy
> load. If you do this for several values of Pin, you'll be able to plot all
> of
> those measured points on the graph. It will look like a pretty straight
> line
> toward the lower Pin values, then it will flatten out (become more
> horizontal)
> as Pin (and Pout) get higher.
>
> The slope of the line is the gain of the amplifier.
>
> Very often the Pin values are 1 dB apart. One dB is about a 25% increase in
> power. Meaning that if you are measuring Pin in Watts, then you can set Pin
> to
> roughly the following values:
>
> 1, 1.5, 2, 3, 4, 5, 7, 10, 13 Watts, etc.,
>
> and measure the Pout at each value. The values should be converted to dBm
> before
> plotting. That's all there is to it.
>
> This is all done in CW mode. If you want to go further, you can go into SSB
> mode
> and apply two tones to the amp (which a K3 has the ability to do) and then
> look
> at the output of both the K3 and the KPA500 with a spectrum analyzer... but
> I'll
> leave that explanation for another day... or it can be found on the web.
>
> Al W6LX
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