http://elecraft.85.s1.nabble.com/KPA-500-Output-for-Input-schedule-tp6352735p6354054.html
I imported Gary's measured data to analyze it. It's a little bit difficult,
because I'm just using a graphical method (a.k.a. 'eyeballing') to try and find
highest power point. I estimate, if we extrapolate out a little bit, that the
1dB point is at about 45 W input power (at approx. 700 W output). One of the
obvious sources of error, if you plot the data, is the linearity of Gary's power
The RFsensing on the K3 is a real trick. The frst 'dit' may suffer a mild
Low power band changing does occur with 1W on CW. Tested it just now with a
> Joe,
>
> Just to clarify, the last measurements were on 28.447.44 (a clear frequency
> here at the moment), SWR is 1.1:1, tri-band yagi.
>
>
> On 12 May 2011 08:40, Gary Gregory <
[hidden email]> wrote:
>
>> Joe,
>>
>> 325W @ 15W drive
>> 410W @ 20W drive
>> 490W @ 25W drive
>> 510W @ 26W drive
>> 530W @ 27W drive
>> 560W @ 28W drive
>> 580W @ 29W drive
>> 600W @ 30W drive
>> 630W @ 31W drive
>> 650W @ 32W drive
>> 675W @ 35W drive
>> 690W @ 37W drive
>> 700W @ 40W drive
>>
>> Is this still about right for your calculations.....
>>
>> Gary
>>
>>
>> On 12 May 2011 08:18, Joe Subich, W4TV <
[hidden email]> wrote:
>>
>>>
>>> Adding gain calculation ...
>>>
>>>
>>> > 2W = 30W 11.8 dB
>>> > 2.5W = 40W 12.0 dB
>>> > 3w = 50w 12.2 dB
>>> > 3.5w = 60w 12.3 dB
>>> > 4w = 70w 12.4 dB
>>> > 4.5w = 75w 12.2 dB
>>> > 5w = 80w 12.0 dB
>>> > 5.5w = 90w 12.1 dB
>>> > 6w = 100w 12.2 dB
>>> > 6.5w = 110w 12.3 dB
>>> > 7w = 120w 12.3 dB
>>> > 7.5w = 130w 12.4 dB
>>> > 8w = 150w 12.7 dB
>>> > 8.5w = 160w 12.7 dB
>>> > 9w = 170w 12.8 dB
>>> > 9.5w = 180w 12.8 dB
>>> > 10w = 190w 12.8 dB
>>> > 11w = 200w 12.6 dB
>>> > 12w = 225w 12.7 dB
>>>
>>> The numbers look about right including the decreased gain at low level
>>> (as expected). Using 12.6/12.7 dB would indicate 33W drive for 600W
>>> out. 40W drive for 600W output would indicate ~1 dB of compression.
>>>
>>> 73,
>>>
>>> ... Joe, W4TV
>>>
>>> On 5/11/2011 5:28 PM, Gary Gregory wrote:
>>> > 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<
[hidden email]> 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
>>> >> ______________________________________________________________
>>> >> Elecraft mailing list
>>> >> Home:
http://mailman.qth.net/mailman/listinfo/elecraft>>> >> Help:
http://mailman.qth.net/mmfaq.htm>>> >> Post: mailto:
[hidden email]
>>> >>
>>> >> This list hosted by:
http://www.qsl.net>>> >> Please help support this email list:
http://www.qsl.net/donate.html>>> >>
>>> >
>>> >
>>> >
>>> ______________________________________________________________
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http://mailman.qth.net/mmfaq.htm>>> Post: mailto:
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>>>
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>>
>>
>>
>> --
>>
>> VK4FD - Motorhome Mobile
>> Elecraft Equipment
>> K3 #679, KPA-500 #018
>> Living the dream!!!
>>
>>
>
>
> --
>
> VK4FD - Motorhome Mobile
> Elecraft Equipment
> K3 #679, KPA-500 #018
> Living the dream!!!
>
>