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## [Amps] tank calculations - need input

 To: [Amps] tank calculations - need input "ka1mwp" Sat, 17 Oct 2009 16:49:39 -0400 mailto:amps@contesting.com>
 ```GU-84b based amp ? tetrode boards for control. OK so, working again on my amp, 2.3kv on plate, 350v (when ON) to G2 and G1 has -65v. I have well over 1 amp available for plate current if needed. Used several tank calculators, Jim Hawkins, PI network v1.0, G4FGQ?s calculator..whatever Else I could find out there to do comparisons. Found out that the W4ZT calculator was pretty close. I used about 940ohm for my plate impedance, I can run 1, 1.5, 2kw calculations but I started with 1.8kw. assumed that the tank Q Was 12 ? 12.5, Rp made 968 ohms. I set this all up with my Boonton inductance meter, cap meter on the C1 and C2 (all out of circuit) and assembled it. I have done this Several times. I used my MFJ analyzer and setup the circuit, tube in place connected just swept the tank and looked OK. Power up - 3.8mhz, C1 ? variable to 0 to 500pf, vacuum cap. Set as needed C2 ? variable to 1000pf vacuum cap PLUS THREE 470pf Russian door knob caps. 1400- 2400pf total available. (I checked these with cap meter all ok) Set that as needed. Inductance pretty close to 5uh a little below, I had to short one coil section to get it there as I am using the whole coil I wound Out of ¼ copper tube ? wound over a Krylon spray can. Now then? Problem I am CONSTANTLY having is to have tons of C2, like the vacuum cap has no more, seems like both 80m (and 40m I tapped the coil there for 40 also). I can pull easily 1.5kw out on both these bands but its with the vacuum cap out all the way (max capacitance) and When I am turning the cap in (decrease pf) the power decreases. And I do see the grid current start to drop also. I switched from a 600pf to 1000pf vacuum cap to see what that would do and it still wanted more. I have checked the total C2 pf readings they look OK. What?s wrong with this picture?? Now what direction should I go in here with this? Assume different Rp and see what I can poke and hope with? Thanks ?Chuck ~ka1mwp _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps ```
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