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-   -   6H30 VA stage? (http://www.diyaudio.com/forums/tubes-valves/225352-6h30-va-stage.html)

deicide67 10th December 2012 12:12 AM

6H30 VA stage?
 
Does anyone have a link to a 6H30 as a VA stage? I am working on an amp, and I have 184V on the plates with a 28.8K anode resistor, and 11.7V on the cathode. Just wondering what is "normal" for this tube. I have a 1.5K cathode resistor.

Thanks for any information!

Blair

Charm 10th December 2012 05:44 AM

http://klausmobile.narod.ru/testerfiles/6n30p.htm

''Исток2''. Радиолампы - почтой. Параметры и характеристики 6Н30П-ДР классика

Next-Tube. Справочные данные по лампам и трансформаторным сердечникам.

http://www.tubes.ru/techinfo/HiFiAudio/6n30pdr.html

http://www.tubeampdoctor.com/images/...ns%206N30P.pdf

Google steers!

deicide67 10th December 2012 11:31 AM

Hi,

Thank you! I can find the tube data, but I wanted to see if anyone had a working schematic of this tube as the VA stage of their or a commercial amplifier. In my amp, I have:

Using a 28.8K plate resistor and 1.5K cathode resistor:

184V on the plate, and 11.7V on my cathodes.

I have never seen cathode voltage that high in a VA stage and wondered if it looked OK to run like this.

Thank you!

Blair

TheGimp 10th December 2012 12:03 PM

You are running 7.8mA for cathode current, which is well within the spec of the tube.

However, this is a low for best performance for this tube. Also your anode voltage is a too high. The two together will put you out of the most linear bias region.

I would suggest decreasing your cathode resistor significantly, to increase anode current and lower anode voltage.

deicide67 10th December 2012 12:13 PM

Thanks!

Looking at the tube specs, it looks like I need to also decrease the plate resistor from almost 30k to around 6-10K and change my dropping resistor in my PS to lower the plate voltage.

You think 250-560 ohms for the cathode resistor?

Ill tinker with it and post some voltages if you don't mind.

Thanks again!

Blair

12B4A 10th December 2012 12:28 PM

pRC put some 6H30Pi experimentation up on his website. AudioVidioPhilia: Mambo Foreplay

deicide67 10th December 2012 02:41 PM

I tinkered with it a bit by changing the dropping resistor, plate and cathode resistor.

Now, I have a B+ of around 150V

72V on the plates, and 3.45V on the cathodes.

Look better?

Thanks?

Blair

euro21 10th December 2012 04:51 PM

1 Attachment(s)
My suggestion.

12B4A 10th December 2012 07:36 PM

Is that for both sections in parallel?

deicide67 10th December 2012 07:58 PM

It was a single side. I ditched the 6H30. It acted very unstable and both that I have are fairly noisy. I had some wicked 120hz artifacts.

I swapped plate resistors, changed my cathode resistor, dropped a 6CG7 in and away went the noise and wobbly sine waves.

I got the 6H30s from a buddy, so god knows what they went through.

Thanks!


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