Hi there...
I have few of these great tubes on my DIY stock and two polish made 5k2 OPT's. Now I am in process of design some simple SE amp with 4P1L tubes in triode mode. I am little confused with data presented in original datasheets. On one page I found data that 2nd grid maximum disipation is 1,5W and for triode connected tube this value is limiting factor (not the anode disipation of 7,5W?). Looking on chart Ip vs Vp and with power envelope of 1,5W my only space for operating point is in lower part of chart and with low voltages.
Please help me with some aditional data:
is nominal value of 1,5W actual value for maximum power disipation of tube in triode mode or is maximum disipation up to plate power of 7,5W?
I even found some calculations on web with note that power pentode maximum disipation in triode mode is in fact sum of 2nd grid and plate disipation.
What is in fact true for triode mode?
Thank You in advance and take care...
Dubravko
I have few of these great tubes on my DIY stock and two polish made 5k2 OPT's. Now I am in process of design some simple SE amp with 4P1L tubes in triode mode. I am little confused with data presented in original datasheets. On one page I found data that 2nd grid maximum disipation is 1,5W and for triode connected tube this value is limiting factor (not the anode disipation of 7,5W?). Looking on chart Ip vs Vp and with power envelope of 1,5W my only space for operating point is in lower part of chart and with low voltages.
Please help me with some aditional data:
is nominal value of 1,5W actual value for maximum power disipation of tube in triode mode or is maximum disipation up to plate power of 7,5W?
I even found some calculations on web with note that power pentode maximum disipation in triode mode is in fact sum of 2nd grid and plate disipation.
What is in fact true for triode mode?
Thank You in advance and take care...
Dubravko
I can't find the second statement in any of the datasheets. Can you please share?
That's generally true (apart from the fact that you can't always be sure of what percent of the total power dissipation goes to each electrode)
The sum of G2 and anode power is correct.
You may have to be careful about g2 current - I'm novice myself and havent used 4P1L.
You may have to be careful about g2 current - I'm novice myself and havent used 4P1L.
In same datasheet is noted that maximum 2nd grid current is 7mA. So, total disipated power is 1,5+7,5W but with limitation of 2nd grid current must be below 7mA. Is that correct?
I know that G2 Pmax is 1.5W.
I'm asking where you've found the statement that this value is limiting factor for triode connection?
This is my mistake in writing.
Calculation of conditions of triode operated pentode is new area for me, but in any case 2nd grid electrical data are most limiting in triode mode? If I make some sort of current balance between 2nd grid and plate then will be possible to disipate full nominal power 1,5+7,5W on tube.
Calculation of conditions of triode operated pentode is new area for me, but in any case 2nd grid electrical data are most limiting in triode mode? If I make some sort of current balance between 2nd grid and plate then will be possible to disipate full nominal power 1,5+7,5W on tube.
Well, technically yes, but I personally woudn't go over 7.5W of total dissipation, especially with higher plate voltages (around 250V).
My idea is to put voltage regulator in between of main rectifier tube and each channel because my transformer gives 350Vdc after rectification and smoothing. Design of regulator will be proven 6С19П / 6Ж1П-ЕВ / СГ3С simple circuit. Sonicaly this solution is not the best one but for test of amp circuit will do. First stage of amp will be KC1 DHT.
