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Old 27th July 2014, 10:44 AM   #1
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Default best operating points for e182cc tube

hi,
im trying to find the best operating points for the e182cc in dac output stage,
im using pcm1704 dac chip conectec to a pot. (volume control) and than straight to the grid of e182cc tubes through 1k resistor in series,
-grid resistor (to ground) at the moment is 360K.
-cathode resistor 330R
-anode voltage 220V
-current .around 13ma
....if you have any comments or suggestions please let me know.
best,k.
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Old 27th July 2014, 02:02 PM   #2
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You have forgotten to state your anode resistance, and also if the tube is supposed to be working as a buffer or a amplifying stage.

If the latter, have you bypassed the cathode? This will give you more gain.

Anyway, the E182CC can handle some power, however I would use it quite conservatively. There is little point in running this tube that hard.
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Old 27th July 2014, 02:22 PM   #3
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hi v4lve lover,
thanx for your reply,
the anode resistance is 8kohm
tube is working as amplifying stage
no cathode bypass
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Old 27th July 2014, 03:53 PM   #4
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Hi,
I have operate the tube at 120V@20mA with a CCS.
Btw when you run the tube hard only use one half. When it gets to warm it sounds strange. This goes for the 5687 as well.
When using a CCS as load you can take the cathode C out.

Best
Karsten
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Old 27th July 2014, 04:15 PM   #5
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Why would you only use one half?

Why not just load both halves whit a CCS set at 5-7mA?
that way you are not heating one side you won't use
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Old 13th August 2014, 06:59 PM   #6
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Hi,
If you run at low current like 5mA the tube will not reach its spec. Check out the data sheet. You will see at 5mA that gm is low and Rp is high.
Run only one half of the tube due to temperature. The tube sounds odd when it is too warm.

Best
Karsten
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Old 13th August 2014, 08:30 PM   #7
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Attached is the specified operating conditions of Rl = 8k ohms, Ebb = 220V. You could choose an operating point anywhere along this 8k load line. I would stack a couple of 1.2V or 1.4V red LEDs as the cathode bias and expect the plate voltage to be about 100V with a plate current of about 12mA and Eg = -2.8V.
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Old 1st September 2014, 05:13 AM   #8
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Quote:
Originally Posted by Palustris View Post
Attached is the specified operating conditions of Rl = 8k ohms, Ebb = 220V. You could choose an operating point anywhere along this 8k load line. I would stack a couple of 1.2V or 1.4V red LEDs as the cathode bias and expect the plate voltage to be about 100V with a plate current of about 12mA and Eg = -2.8V.
Thanx for your help i will try that s soon as im back home. Traveling a lot at the moment .
Would you please explain where to place the red LEDs and whats the advantage of doing it
Best.
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Old 1st September 2014, 05:37 PM   #9
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Normally one would use a 220r or 240r resistor bypassed by a capacitor to bias the tube for the above example. If one uses a couple of 1.4V LEDs between the cathode and ground to bias the tube, the cathode capacitor can be eliminated.
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Old 1st September 2014, 06:21 PM   #10
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Quote:
Originally Posted by Palustris View Post
Normally one would use a 220r or 240r resistor bypassed by a capacitor to bias the tube for the above example. If one uses a couple of 1.4V LEDs between the cathode and ground to bias the tube, the cathode capacitor can be eliminated.
....I.ve never bypassed cathode to ground resistor either with capacitor or LED....I will try that in future. Could you tell me why you prefer LED over cap as bypass. And what is the usual cap size ?
Can I use mkp or have to be electrolytic?
Best. And many thanx for your time.
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