Closed loop stability help needed.

[TheGimp]

I haven't had a chance to breadboard it yet, but simulations show greater distortion with the screen controlled servo amp than the cathode controlled servo amp.

[aeandm]

I can recommend bring temporary change in diagram.
I imply real device, use oscillograph .I sure in diagram keep error.
Alternative draw another diagram, on this diagram insufficiently information .

[jan.didden]

Originally Posted by TheGimp

I haven't had a chance to breadboard it yet, but simulations show greater distortion with the screen controlled servo amp than the cathode controlled servo amp.

Too much loop gain again. Try 10-50 ohms in series with D3.

jan didden

[TheGimp]

aeandm, the Zener diode actually works on the breadboard. It keeps VGs near 180V. Max screen voltage is specified as 170 for the 6P41S, and it I allow it to go much higher bias voltage must go much lower.

I do not understand your schematic. Am I supposed to bias the screen at a fixed level with the circuit shown?

janneman, I added 33 and eventually got it up to 51Ohms. that helps. tks.

[aeandm]

Originally Posted by TheGimp

aeandm, the Zener diode actually works on the breadboard. It keeps VGs near 180V. Max screen voltage is specified as 170 for the 6P41S, and it I allow it to go much higher bias voltage must go much lower.

I do not understand your schematic. Am I supposed to bias the screen at a fixed level with the circuit shown?

janneman, I added 33 and eventually got it up to 51Ohms. that helps. tks.

Ask colleague Wavebourn translate: Мне не понятна схема где питание драйвера
связано с раскачкой выходного каскада, на транзисторах реализован эл. фильтр, зачем сигнал подан на него(33К) и где минус фиксированого смещения? Поэтому и предложил временно упростить, может я
чего-то не знаю?

[Wavebourn]

Originally Posted by aeandm

Ask colleague Wavebourn translate: Мне не понятна схема где питание драйвера
связано с раскачкой выходного каскада, на транзисторах реализован эл. фильтр, зачем сигнал подан на него(33К) и где минус фиксированого смещения? Поэтому и предложил временно упростить, может я
чего-то не знаю?

Скорее всего Вы не знаете того, что я пытался защитить Вас от модераторов, которые Вас забанят за нарушение правил форума. Если нужна помощь - добро пожаловать в Private Messages. Попросите -- помогу, но переводить каждое Ваше сообщение, написанное по-русски в нарушение правил Форума, я не обещал.

Translation:

What you probably don't know that I tried to save you from being banned by moderators. Did you read forum rules? I offered you to help, but did not promise to translate each message. If you need help please go to Private Messages and ask me there.

[aeandm]

Originally Posted by Wavebourn

Скорее всего Вы не знаете того, что я пытался защитить Вас от модераторов, которые Вас забанят за нарушение правил форума. Если нужна помощь - добро пожаловать в Private Messages. Попросите -- помогу, но переводить каждое Ваше сообщение, написанное по-русски в нарушение правил Форума, я не обещал.

Translation:

What you probably don't know that I tried to save you from being banned by moderators. Did you read forum rules? I offered you to help, but did not promise to translate each message. If you need help please go to Private Messages and ask me there.

Извините там слишком сложно чтобы я перевел(6П41С), а по поводу
предупреждений их можно взять и плавно переместить туда, переведите
как учетную запись aeandm можно удалить здесь мне не интересно

[kevinkr]

Originally Posted by aeandm

Извините там слишком сложно чтобы я перевел(6П41С), а по поводу
предупреждений их можно взять и плавно переместить туда, переведите
как учетную запись aeandm можно удалить здесь мне не интересно

Anatoliy is right, you need to send this to him via PM, and ask him nicely for help as he is probably very busy.. I understand English is not your native language but as he points out you are violating the English language forum policy. (However don't give up perhaps you'll get the hang of the language over time.)

[TheGimp]

This has been a rather interesting exercise. So far I've only had time to run simulations and it will probably be the weekend before I can get my tubelab back on the bench to verify the results.

Both circuits produce the same results (or so close as to be the same) given that the anode current and grid to cathode voltage are the same and the screen voltage is adjusted to produce the same cathode current. The input voltage is nearly the same to produce the same output voltage under these conditions.

Unfortunately both produce fairly high distortion (25%) at 1W, 2.8Vrms into 8 ohms.

[kevinkr]

Originally Posted by TheGimp

This has been a rather interesting exercise. So far I've only had time to run simulations and it will probably be the weekend before I can get my tubelab back on the bench to verify the results.

Both circuits produce the same results (or so close as to be the same) given that the anode current and grid to cathode voltage are the same and the screen voltage is adjusted to produce the same cathode current. The input voltage is nearly the same to produce the same output voltage under these conditions.

Unfortunately both produce fairly high distortion (25%) at 1W, 2.8Vrms into 8 ohms.

Looks like an interesting exercise, and somehow I think you will eventually get it to perform the way you want, but you are most definitely the master of understatement - 25% indeed..