4P1L

8 thoughts on “4P1L”

1. Pentode curves! Good job Ale, thanks. Do you have any info about G2 current value?
   Just finished pentode spice model, but Ig2 looks like too large.

   Reply

   1. Hi,
      No, unfortunately don’t have info on screen current.
      Can you share the pentode model?
      Thanks
      Ale

      Reply

      1. Ofcourse. This is a LT spice model.
         KG2 (Inverse Ig2 sensitivity) is a sizable. But who knows, perhaps it is good.

         .SUBCKT 4P1L 1 4 2 3 ; Ug2=150V; (E74GD – 6.1.13.)
         + PARAMS: MU= 9.2 EX= 1.362 KG1= 1468 KP=510 KG2=4200
         + KVB= 48.8 VCT= 0.00 RGI=220
         + CCG=9P CPG1=0.1P CCP=9.5P
         RE1 7 0 1G
         RE2 8 3 1G
         E1 7 0 VALUE= ; E1 BREAKS UP LONG EQUATION FOR G1.
         +{V(4,3)/KP*LOG(1+EXP((1/MU+V(2,3)/V(4,3))*KP))}
         G1 1 3 VALUE={(PWR(V(7),EX)+PWRS(V(7),EX))/KG1*ATAN(V(1,3)/KVB)}
         G2 8 3 VALUE={(PWR(V(7),EX)+PWRS(V(7),EX))/KG2*(2.5708-ATAN(V(1,3)/KVB))}
         E2 8 4 VALUE={0}
         RCP 1 3 1G ; FOR CONVERGENCE
         C1 2 3 {CCG} ; CATHODE-GRID 1
         C2 1 2 {CPG1} ; GRID 1-PLATE
         C3 1 3 {CCP} ; CATHODE-PLATE
         R1 2 5 {RGI} ; FOR GRID CURRENT
         D3 5 3 DX ; FOR GRID CURRENT
         .MODEL DX D(IS=1N RS=1 CJO=10PF TT=1N)
         .ENDS

         Reply

         1. Thanks,
            Just tried my version of it, see the post I created on 4P1L pentode spice model. Can you try the model?
            cheers
            ale

            Reply

            1. Yes Ale, I can when involved your values ​​in my model.
               Beautiful !!!
               Im big fan of pentode mode drivers for output triodes. I have C3g ->300B and
               C3m ->6C33C.

               Just tried the first attempt to simulate 4p1L->300B with 5K OPT primary.
               Very encouraging !

               Vin=2Vrms, Pout=8,7Wrms, THD=1,8% (k2=-18dB, k3=-17dB, k4=-53%, k5=-59dB, k7=-70dB).

               4P1L op. point:
               240V/90V/-4,2V, Ia=15mA, Ig2=5,5mA.
               Low current CCS`ed shunt fed series mosfet to regulate Ug2.
               RC filter on cathode,
               Ra=6K8

               Rajko

            2. Great, please test it and let me know.
               4P1L likes currents above 20mA. What is the distortion of the driver?
               I’m sure I did my tests in the wrong bias point
               The mu follower gyrator is better as a load for a driver, I wouldn’t use an CCS..
               ale

2. Forget pentode with CCS.
   I will try gyrator.

   Ale, any email for possible send some picture or sch ?

   Reply

   1. Yes send it to my email valves @ bartola.co.uk
      Cheers
      Ale

      Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.