LS50.....GU50 Translation Please

[pl802]

Would a German speaker please translate this data for me.....much appreciated.

 

[Kay Pirinha]

Well, here we are:


Left pic:
Operating data as a triode
13. Screen tied to plate, suppressor grounded
Heater voltage 12.6 V
Max. plate supply voltage 400 V
Max. plate voltage 800 V
Max. plate dissipation 40 W
Max. plate idle current 30 mA
µ = 20
gm = 2 mS


Right pic:
14. Control and screen grids connected (suppressor grounded)
Heater voltage 12.6 V
Max. plate supply voltage 1000 V
Max. plate dissipation 40 W
Max. plate idle current 30 mA
µ = 28,6
gm = 5 mS


Hope that helps!

 

[pl802]

Thank you Kay Pirinha.

 

[pl802]

Hold on that means rp=10K in triode mode!
And Rl is usually 3 times rp
What am I missing here?

 

[32860]

See next post.

 

[32860]

"Durchgriff" = (1/mu) x 100%

So 20% corresponds with mu = 5 and 0,35 % with mu = 285

Edit: I am not so sure about the max. idle current of 30 mA in triode mode. That value looks too low to me. But this value appears in more datahseets (EL152, FL152, P50) so it's a bit of a mistery to me.

Edit 2: I found this so the 30 mA must be wrong.

 

[pl802]

''So 20% corresponds with mu = 5 and 0,35 % with mu = 285''
In Triode mode rp=2k5 and Rl would be at least 3 times that or 7k5.
Actually a 10K loadline looks good.

 

[TG]

I have no experience with LS-50, but GU-50's plate resistance in triode mode is about 800-900 Ohm

 

[pl802]

TG would you post your data here please....much appreciated.

 

[TG]

TG would you post your data here please....much appreciated.

 

[brightcity]

I believe they are for different specific use cases irregardless of same socket and pin out. That and the possible inclusion of a zirconium (high temp + self healing) getter with the standard barium getter.

 

[TG]

I believe they are for different specific use cases irregardless of same socket and pin out.

GU-50 is technically the LS-50 clone, but copies aren't always equal to their prototypes indeed

 

[brightcity]

Cool, good to remember.

 

[pl802]

Thanks TG
Not that far off

 

[RajkoM]

From triode curves posted here, anode resistance for LS50 is 1k2 and 1k1 for GU50

 

[TG]

That's just wasting the tube 😀
Push-pull, 400V B+, 100mA per tube, Ra-a=6.6k - about 25-30 clean watts at the output (GU-50 is not very well suited for SE due to large 2nd harmonic)

 

[pl802]

Hi RajkoM.
Would you post your calculations here please....much appreciated.
Tube math is something I would like to learn!

 

[RajkoM]

From tangent: Rp = Ua/Ia = 230V/220mA = 1045 ohms

 

[pl802]

''Ua/Ia = 230V/220mA''
This is not arbitary.....how have you selected for these points on the curve?
Also would you explain that line running from 50V to 230V.
Thanks for your patience

 

[RajkoM]

From tangent you can select point you want. Usually a point is taken somewhere at the top of the tangent.

The tangent is drawn exactly on the curve where the operating point is. I chose Ia = 40mA at Ug = 0V just for example.