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## [AMPS] L-Net calculations: Am I doing something wrong?

 To: [AMPS] L-Net calculations: Am I doing something wrong? measures@vc.net (Rich Measures) Wed, 17 Feb 1999 14:43:06 -0800
 ``` >>>>? RL depends on the ZSAC. ? (Zero Signal Anode Current) >>>>With higher idle current, RL decreases. >>>>Using RL=DCV/2 x I-anode, at 0.8A, RL=3.125k-ohms. Designing for a Q of >>>>15 at 28MHz, a Pi-L with an intermediate Z of 300-ohms, XC1=208 ohms, >>>>C1=26pF. L1=1.5uH. L2=0.64uH. C-load=129pF. Subtracting 10pF for the >>>>C-anode + stray C, C-tune is 18pF. The min. C of a UCS-300 is 5pF. Have >>>>I missed something? > >OK, so I owe you a pizza! > ? ok. If you are ever in the area, we could do lunch. >Some guys use a 1.8 number as the multiplication factor for I-anode. ? With an 8877, or a similar triode, so would I. >No matter, it still is much less than the 4600 Ohms I was using. > >Using your formula, the 4600 Ohms assumes an I-anode of c.500 mA. > >OK, so answer this then: Why am I having problems matching on 10m? ? I would have to measure some things to figure it out. >Why does my power output top out at 800 Watts? Once I get over 60 watts of >drive, I get no more power out no matter what I do. ? Sounds like a tuned input problem. What is C1? >In looking at everything I was assuming it was becasue Q was too high. > >What light can you shed on this? > >Also, how do you determine your peak anode current. ? look at the constant-current characteristic curves. For good linearity, pick the highest peak-current curve that has a defined knee at the anode/plate potential equal to the screen-supply voltage. For the 8166/4-1000A, the highest such curve is 2.6 peak-amps. Divide peak-current by 3 to obtain avg. current. This is how I arrived at the c. 0.8A figure. >The current will >change depending on what amount of drive you have applied to the amp. So >I what I think you are saying is that you would need to drive the amp so >that the plate current is at 0.8 A. But then if you decrease the drive, >you would change the impedance and hence the match. Correct? > ? yes x 3. The guy who wants to take it easy on his linear amp. and tunes up with reduced drive, gets a mistune every time. . . - cheers, Jon Rich... R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures -- FAQ on WWW: http://www.contesting.com/ampfaq.html Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com Search: http://www.contesting.com/km9p/search.htm ```
 Current Thread [AMPS] L-Net calculations: Am I doing something wrong?, (continued) [AMPS] L-Net calculations: Am I doing something wrong?, Rich Measures [AMPS] L-Net calculations: Am I doing something wrong?, Jon Ogden [AMPS] L-Net calculations: Am I doing something wrong?, Rich Measures [AMPS] L-Net calculations: Am I doing something wrong?, Peter Chadwick [AMPS] L-Net calculations: Am I doing something wrong?, Rich Measures [AMPS] L-Net calculations: Am I doing something wrong?, Peter Chadwick [AMPS] L-Net calculations: Am I doing something wrong?, Jon Ogden [AMPS] L-Net calculations: Am I doing something wrong?, Rich Measures [AMPS] L-Net calculations: Am I doing something wrong?, Jon Ogden [AMPS] L-Net calculations: Am I doing something wrong?, Rich Measures [AMPS] L-Net calculations: Am I doing something wrong?, Rich Measures <= [AMPS] L-Net calculations: Am I doing something wrong?, Rich Measures [AMPS] L-Net calculations: Am I doing something wrong?, Jon Ogden [AMPS] L-Net calculations: Am I doing something wrong?, km1h@juno.com [AMPS] L-Net calculations: Am I doing something wrong?, km1h@juno.com [AMPS] L-Net calculations: Am I doing something wrong?, Rich Measures [AMPS] L-Net calculations: Am I doing something wrong?, Peter Chadwick [AMPS] L-Net calculations: Am I doing something wrong?, Rich Measures [AMPS] L-Net calculations: Am I doing something wrong?, Peter Chadwick [AMPS] L-Net calculations: Am I doing something wrong?, Jon Ogden [AMPS] L-Net calculations: Am I doing something wrong?, Jon Ogden