Hi, a friend interested in EF37 and other very similar tubes. I made PSpice model for triode connection, as in the data-sheet.
G2-K, G3-A.
I could not find the value of capacitances in triode mode mode.
Cga and Cak are used from the pentode mode, BUT Cga is missing.
I approximated a bit smaller than input capacitance to 4pF.
So if someone have informations of triode mode capacitance for these tubes please send?
Thanks.
.
This is pretty linear tube. But it has some specifics... In resistive mode load, for linear least distortion mode, Vb is reaching more than 400V of HV value. That is not the issue to use with power tubes which are already have higher HV Vb value to use for this tube.
.
Another option is L load. But that may deserve higher value of inductance, implicating to higher capacitance for more turns. Because the internal resistance is aprox. 9700 ohms... these tubes are not so powerful drivers because of the higher internal resistance and Zout of about 7800 ohms. But distortion is low for that huge output p-p swings and input will not go into positive range in the Ug = -3V for 2Vrms input...
.
Maybe the best option to avoid that high voltage, complicated inductance is some SRPP mode, or Gyrator load?
Gyrator load is introducing non-vacuum tubes elements, that might be not acceptable for tube purists 🙂. But may be an argument to have more affordable and compact load, and if we use these elements in load why not to use them in the PS regulator supply?
.
Al in all there is very useful tube in triode mode as in pentode mode.
Some of the informations as working point values, loads, internal resistance, input and output voltages, output resistance...
.
Copy code content and make .inc file with some TXT soft. Just rename .txt into .inc for PSpice.
You can reuse it in Tools soft and remake LTspice version?
cheers
.
G2-K, G3-A.
I could not find the value of capacitances in triode mode mode.
Cga and Cak are used from the pentode mode, BUT Cga is missing.
I approximated a bit smaller than input capacitance to 4pF.
So if someone have informations of triode mode capacitance for these tubes please send?
Thanks.
.
This is pretty linear tube. But it has some specifics... In resistive mode load, for linear least distortion mode, Vb is reaching more than 400V of HV value. That is not the issue to use with power tubes which are already have higher HV Vb value to use for this tube.
.
Another option is L load. But that may deserve higher value of inductance, implicating to higher capacitance for more turns. Because the internal resistance is aprox. 9700 ohms... these tubes are not so powerful drivers because of the higher internal resistance and Zout of about 7800 ohms. But distortion is low for that huge output p-p swings and input will not go into positive range in the Ug = -3V for 2Vrms input...
.
Maybe the best option to avoid that high voltage, complicated inductance is some SRPP mode, or Gyrator load?
Gyrator load is introducing non-vacuum tubes elements, that might be not acceptable for tube purists 🙂. But may be an argument to have more affordable and compact load, and if we use these elements in load why not to use them in the PS regulator supply?
.
Al in all there is very useful tube in triode mode as in pentode mode.
Some of the informations as working point values, loads, internal resistance, input and output voltages, output resistance...
.
Code:
**********************************************
* Created on 10/12/2024 19:35 using paint_kit.jar 3.1
* www.dmitrynizh.com/tubeparams_image.htm
* Plate Curves image file:
* Data source link: mullard ef37 pdf, G3-A, G2-K
Model can be used for EF6 EF36 CV358 and other equivalents
*----------------------------------------------------------------------------------
.SUBCKT EF37_triode 1 2 3 ; Plate Grid Cathode
+ PARAMS:
+ MU=28.4
+ KG1=1455.45
+ KP=237.5
+ KVB=300
+ VCT=0.65
+ EX=1.39
+ RGI=2000
*----------------------------------------------------------------------------------
* capacitances witout socket, for socket add 0.7pF to each capacitance...
*----------------------------------------------------------------------------------
CCG=5.5P
CGP=4P; this capacitance is estimated
CCP=8.5P
*----------------------------------------------------------------------------------
* Vp_MAX=450 Ip_MAX=17.5 Vg_step=1 Vg_start=2 Vg_count=16
* Rp=40000 Vg_ac=2.21 P_max=1.3 Vg_qui=-3 Vp_qui=153
* X_MIN=67 Y_MIN=20 X_SIZE=944 Y_SIZE=747 FSZ_X=1821 FSZ_Y=897 XYGrid=true
* showLoadLine=y showIp=y isDHT=n isPP=n isAsymPP=n showDissipLimit=y
* showIg1=n gridLevel2=n isInputSnapped=n
* XYProjections=y harmonicPlot=y dissipPlot=y
*----------------------------------------------------------------------------------
E1 7 0 VALUE={V(1,3)/KP*LOG(1+EXP(KP*(1/MU+(VCT+V(2,3))/SQRT(KVB+V(1,3)*V(1,3)))))}
RE1 7 0 1G ; TO AVOID FLOATING NODES
G1 1 3 VALUE={(PWR(V(7),EX)+PWRS(V(7),EX))/KG1}
RCP 1 3 1G ; TO AVOID FLOATING NODES
C1 2 3 {CCG} ; CATHODE-GRID
C2 2 1 {CGP} ; GRID=PLATE
C3 1 3 {CCP} ; CATHODE-PLATE
D3 5 3 DX ; POSITIVE GRID CURRENT
R1 2 5 {RGI} ; POSITIVE GRID CURRENT
.MODEL DX D(IS=1N RS=1 CJO=10PF TT=1N)
.ENDS F37_triode
*$Copy code content and make .inc file with some TXT soft. Just rename .txt into .inc for PSpice.
You can reuse it in Tools soft and remake LTspice version?
cheers
.
Comparing EF6 and EF37 anode chrs in triode mode.
pretty much the same chrs, but different base and socket...
.
pretty much the same chrs, but different base and socket...
.
The gain is with RL=40Kohm load,
Vin=2 x 2.21Vp-p=4.42Vp-p
Vout = 100Vp-p cca
-A=100Vp-p/4.42Vp-p=22.62 cca.
We can expect value of dynamic capacitance, with estimated 4pF of Cga, about:
Cdyn=Cgk+[(I-AI+1) x Cga]=5.5pF+(23.62 x 4pF)
Cdyn = 96pF
Without optional socket-pins capacitance of 0.7pF added to each.
.
for instance if we want -0.1db@20K that will be -3db@131KHz acc.
So the pot value is
Rpot=1 / (2 Pi F Cdyn)
Rpot=12655 ohm
.
That is without Output resistance of source coming before the input.
So if it is say 2500 ohm of output resistance of some preamp, riaa pre-pre or some other tube device,
that value should be substracted from max pot value.
Al this for not to have roll of when levels are low.
.
When levels are low, the almost all value of por is in serial connected to the input creating with the Cdynamic
a Filter. So 10K-15K-22K standard pot will do the job. With say 1meg from pot C.T. and Grid to GND to ensure connection if the wiper pot is lose connection...
And should take a care for output resistance of the source, to be low enough to drive that pot as load,
It probably should have a buffer at the output.
.
Vin=2 x 2.21Vp-p=4.42Vp-p
Vout = 100Vp-p cca
-A=100Vp-p/4.42Vp-p=22.62 cca.
We can expect value of dynamic capacitance, with estimated 4pF of Cga, about:
Cdyn=Cgk+[(I-AI+1) x Cga]=5.5pF+(23.62 x 4pF)
Cdyn = 96pF
Without optional socket-pins capacitance of 0.7pF added to each.
.
for instance if we want -0.1db@20K that will be -3db@131KHz acc.
So the pot value is
Rpot=1 / (2 Pi F Cdyn)
Rpot=12655 ohm
.
That is without Output resistance of source coming before the input.
So if it is say 2500 ohm of output resistance of some preamp, riaa pre-pre or some other tube device,
that value should be substracted from max pot value.
Al this for not to have roll of when levels are low.
.
When levels are low, the almost all value of por is in serial connected to the input creating with the Cdynamic
a Filter. So 10K-15K-22K standard pot will do the job. With say 1meg from pot C.T. and Grid to GND to ensure connection if the wiper pot is lose connection...
And should take a care for output resistance of the source, to be low enough to drive that pot as load,
It probably should have a buffer at the output.
.
Pspice and Ltspice both use the same pin sequence for triodes, not pentodes.
So your triode model should work in Ltspice as is.
In this post Adrian describes a relatively simple way to measure Cag of a triode connected pentode:
And pls post sim models in the sticky tube models thread on this forum,
it is kind of a big data bank for models and easier to search ...
Thanks but i already went trouhg these pdf-s.
How I get the datas for anode characteristic? 🙂
.
Prbaby it can be change in capacitance values because from the sat very similar type of tube 6C6 capacitance are given for triode opperation?
this is for EF37 in pentode
6C6, 6J7 capacitances in pentode
Most lightley
the Capacitance in triode mode for EF37 are sometn=hing like this:
Cgk = 3.5pF cca.
Cak = 12.5pF cca.
Cga= 1.9pF cca.
And, the capacitance should tale into oscillator circuit when the tube is on heating power.
Because it is closer to real working conditions for specific capacitances in tube.
.
How I get the datas for anode characteristic? 🙂
.
Prbaby it can be change in capacitance values because from the sat very similar type of tube 6C6 capacitance are given for triode opperation?
this is for EF37 in pentode
6C6, 6J7 capacitances in pentode
Most lightley
the Capacitance in triode mode for EF37 are sometn=hing like this:
Cgk = 3.5pF cca.
Cak = 12.5pF cca.
Cga= 1.9pF cca.
OK, LT users probably know that, thanks.
I visit the link and it is useful. But the other capacitance are different from pentode connection. Not only Cga.In this post Adrian describes a relatively simple way to measure Cag of a triode connected pentode:
And, the capacitance should tale into oscillator circuit when the tube is on heating power.
Because it is closer to real working conditions for specific capacitances in tube.
.
corrected capacitance value for more probable values.
And dynamic capacitance and max pot value for .PNG from post on top
Cdyn=3.5pF+(23.62 x 1.9pF)=48.4pF cca.
PotMax=25 Kohm cca.
Better, larger pot value is softer load for source before EF37...
.
And dynamic capacitance and max pot value for .PNG from post on top
Cdyn=3.5pF+(23.62 x 1.9pF)=48.4pF cca.
PotMax=25 Kohm cca.
Better, larger pot value is softer load for source before EF37...
.
Code:
**********************************************
* Created on 10/12/2024 19:35 using paint_kit.jar 3.1
* www.dmitrynizh.com/tubeparams_image.htm
* Plate Curves image file:
* Data source link: mullard ef37 pdf, G3-A, G2-K
Model can be used for EF6 EF36 CV358 and other equivalents
*----------------------------------------------------------------------------------
.SUBCKT EF37_triode 1 2 3 ; Plate Grid Cathode
+ PARAMS:
+ MU=28.4
+ KG1=1455.45
+ KP=237.5
+ KVB=300
+ VCT=0.65
+ EX=1.39
+ RGI=2000
*----------------------------------------------------------------------------------
* Capacitances estimated based on 6C6 similar type tube.
* capacitances witout socket, for socket add 0.7pF to each capacitance...
*----------------------------------------------------------------------------------
CCG=3.5P
CGP=1.9P
CCP=12.5P
*----------------------------------------------------------------------------------
* Vp_MAX=450 Ip_MAX=17.5 Vg_step=1 Vg_start=2 Vg_count=16
* Rp=40000 Vg_ac=2.21 P_max=1.3 Vg_qui=-3 Vp_qui=153
* X_MIN=67 Y_MIN=20 X_SIZE=944 Y_SIZE=747 FSZ_X=1821 FSZ_Y=897 XYGrid=true
* showLoadLine=y showIp=y isDHT=n isPP=n isAsymPP=n showDissipLimit=y
* showIg1=n gridLevel2=n isInputSnapped=n
* XYProjections=y harmonicPlot=y dissipPlot=y
*----------------------------------------------------------------------------------
E1 7 0 VALUE={V(1,3)/KP*LOG(1+EXP(KP*(1/MU+(VCT+V(2,3))/SQRT(KVB+V(1,3)*V(1,3)))))}
RE1 7 0 1G ; TO AVOID FLOATING NODES
G1 1 3 VALUE={(PWR(V(7),EX)+PWRS(V(7),EX))/KG1}
RCP 1 3 1G ; TO AVOID FLOATING NODES
C1 2 3 {CCG} ; CATHODE-GRID
C2 2 1 {CGP} ; GRID=PLATE
C3 1 3 {CCP} ; CATHODE-PLATE
D3 5 3 DX ; POSITIVE GRID CURRENT
R1 2 5 {RGI} ; POSITIVE GRID CURRENT
.MODEL DX D(IS=1N RS=1 CJO=10PF TT=1N)
.ENDS F37_triode
*$6BS7 was something like next generation of 6J7 in a smaller 9 pin envelope, top cap retained for G1.
Capacitance Ca-g is maybe smaller on account of smaller elements inside but his don't know for sure.
There is also 6BR7, more general application of the same type, similar to 6J7, Noval base but no top cap ( and a predecessor for EF86 me thinks ).
It seems that 6BS7 is a "pro" version and is hard to find while 6BR7 can be found.
Just my curiosity at development of these from 6C6-6J7 to little different EF36-EF37 to Noval types 6BS7 & 6BR7 and probably at the end EF86.
Capacitance Ca-g is maybe smaller on account of smaller elements inside but his don't know for sure.
There is also 6BR7, more general application of the same type, similar to 6J7, Noval base but no top cap ( and a predecessor for EF86 me thinks ).
It seems that 6BS7 is a "pro" version and is hard to find while 6BR7 can be found.
Just my curiosity at development of these from 6C6-6J7 to little different EF36-EF37 to Noval types 6BS7 & 6BR7 and probably at the end EF86.