Al, Output was measured using the KPA FW which has proven to be very accurate so far in FT units.
Gary On 12 May 2011 10:10, Al Lorona <alor...@sbcglobal.net> wrote: > 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 > the 1 dB compression point, but it is only compressed about 0.6 dB at > Gary's > 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 > meter, but anyway that's what a first cut at it looks like. > > Al W6LX > > > > > ________________________________ > From: Gary Gregory <garyvk...@gmail.com> > To: "Joe Subich, W4TV" <li...@subich.com> > Cc: elecraft@mailman.qth.net > Sent: Wed, May 11, 2011 3:46:57 PM > Subject: Re: [Elecraft] KPA-500 "Output for Input" schedule? > > The RFsensing on the K3 is a real trick. The frst 'dit' may suffer a mild > truncation on band change, but this only happens if you don't press a band > button prior to transmitting. > > Low power band changing does occur with 1W on CW. Tested it just now with a > band change from 10M to 15M > > Maybe this is of help? > > Gary > > On 12 May 2011 08:41, Gary Gregory <garyvk...@gmail.com> wrote: > > > 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 <garyvk...@gmail.com> 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 <li...@subich.com> 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<alor...@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 > >>> >> ______________________________________________________________ > >>> >> Elecraft mailing list > >>> >> Home: http://mailman.qth.net/mailman/listinfo/elecraft > >>> >> Help: http://mailman.qth.net/mmfaq.htm > >>> >> Post: mailto:Elecraft@mailman.qth.net > >>> >> > >>> >> This list hosted by: http://www.qsl.net > >>> >> Please help support this email list: http://www.qsl.net/donate.html > >>> >> > >>> > > >>> > > >>> > > >>> ______________________________________________________________ > >>> Elecraft mailing list > >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft > >>> Help: http://mailman.qth.net/mmfaq.htm > >>> Post: mailto:Elecraft@mailman.qth.net > >>> > >>> This list hosted by: http://www.qsl.net > >>> Please help support this email list: http://www.qsl.net/donate.html > >>> > >> > >> > >> > >> -- > >> > >> 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!!! > > > > > > > -- > > VK4FD - Motorhome Mobile > Elecraft Equipment > K3 #679, KPA-500 #018 > Living the dream!!! > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > -- VK4FD - Motorhome Mobile Elecraft Equipment K3 #679, KPA-500 #018 Living the dream!!! ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
