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Old 7th January 2004, 12:29 AM   #11
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Konnichiwa,

Quote:
Originally posted by fdegrove

I just wondered why the Philips datasheets state Vg3 at 0V for a triode connected E55L.
They cannot seem to be able to make up their minds. I have equally seen datasheets with both extra Grids anoded....

Quote:
Originally posted by fdegrove

As these datasheets don't provide operating curves for your suggested connections, I assume you draw the curves yourself and pick operating point from that?
The term is extrapolating. And G3 does not change the operating point (which is intended as "first cut", to be further optimised by listening) that drastically. The curve shape does though in some areas.

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Old 7th January 2004, 12:46 AM   #12
barossi is offline barossi  Germany
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Default Ultrapath

Hi,

what exactly does the Ultrapath capacitor. I have huge Leclance 50uF/500V + 20uF/500V (i think MP's) Cans on stock. I think i will use them.
I have problems with the following:

After switching on the Amp the 6C33 the operating point at 200mA will reach at about 20min. What could i do against this problem? Could i use a mixture between fixed bias and cathode resistor? (I use now a 10 Ohm resistor at the cathode just to measure the voltage drop with adjustable bias between -50V to - 100V)

Greeting + Thanks

Barossi
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Old 7th January 2004, 12:46 AM   #13
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Hi,

Quote:
They cannot seem to be able to make up their minds.
Yeah...Yet I can understand their reasoning: add a grid to the anode (g2) and another to the cathode (g3) and hope it will balance itself out for most applications.

For all audio purposes I'd tie both grids to the anode, makes more sense to me.

We now have a new valve however and I've no idea if this is going to respond to the laws of physics the way I think it should.

TRIODED PENTODES.

Fascinating how you can make new tubes just by tieing some elements to others...

Frightening for those of us having to work "blind" on this though....

Cheers,

P.S. I vaguelly recall a technical article stating that if you wanted true triode operation for a valve such as an EL34 you needed to tie g2 and g3 to the anode....
If only I could recall where I read it....
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Old 7th January 2004, 12:57 AM   #14
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Hi,

Quote:
what exactly does the Ultrapath capacitor.
Very short answer: it keeps DC out of your xformer.

Quote:
After switching on the Amp the 6C33 the operating point at 200mA will reach at about 20min.
That's normal for a 6C33C.

Quote:
What could i do against this problem? Could i use a mixture between fixed bias and cathode resistor? (I use now a 10 Ohm resistor at the cathode just to measure the voltage drop with adjustable bias between -50V to - 100V)
You can but that's not going to solve that particular problem...
The 6C33C has huge cathodes, so they need time to reach cruising speed.

Just don't play music full blast before they're properly warmed up, you'll hear the distortion right away and they may pop a fuse or cathode resistor if you do.

Cheers,
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Old 7th January 2004, 01:12 AM   #15
barossi is offline barossi  Germany
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Angry Ultrapath

Hello,

are there any "rules" for the ultrapath capacitors?

Greetings Barossi
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Old 7th January 2004, 01:15 AM   #16
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Hi,

Quote:
are there any "rules" for the ultrapath capacitors?
Other than plain math? Don't think so.

Look at it as a coupling cap for the OPT shifted to the cathode and take the math from there.

Cheers,
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Old 7th January 2004, 01:35 AM   #17
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Hey-Hey!!!,
The 'ultrapath' cap does *NOT* keep DC form the output tx. This would be a parafeed arrangement. Ultra-Path is anouther connection completely.
regards,
Douglas
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Old 7th January 2004, 01:42 AM   #18
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Hi,

Quote:
The 'ultrapath' cap does *NOT* keep DC form the output tx. This would be a parafeed arrangement. Ultra-Path is anouther connection completely.
Ha...O.K.

I had parafeed in mind...

Does anyone want to explain the difference between the two?

Hopefully I'm not the only one confused by these two concepts....

Cheers,
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Old 7th January 2004, 01:50 AM   #19
Previously: Kuei Yang Wang
 
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Konnichiwa,

Quote:
Originally posted by fdegrove
We now have a new valve however and I've no idea if this is going to respond to the laws of physics the way I think it should.
From experience - yes, with E810F, E180F, C3m, EL34 and EL84.

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Old 7th January 2004, 02:06 AM   #20
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Hi,

Thank you for the reply.

Quote:
From experience - yes, with E810F, E180F, C3m, EL34 and EL84.
While I do absolutely believe you on this, it's a pity no hard facts seem to be publicised regarding this.

If there are I'd like to be directed to some more precise info even if my instincts and common sense tell me Thorsten is absolutely right here...

Ta,
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