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Old 6th August 2008, 01:52 AM   #1
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Default LTP second grid

I'm building a long tailed pair phase inverter and am wondering what the best thing to do with the second grid is. In others' designs I have seen it connected to ground via a small resistance (10k) or a large one (1Meg). Some even bypass with a capacitor.

What's better, a big or a small resistance? What benefit would bypassing give?
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Old 6th August 2008, 02:09 AM   #2
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It depends on the DC voltage at the first grid. When the first grid is at DC ground, the other grid is generally either grounded directly or used as a feedback point. When the first grid is at an elevated DC potential, the grids are usually connected together with a large-ish resistor (which causes them to assume the same potential), then the second grid is bypassed to ground at AC.
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Old 6th August 2008, 02:47 AM   #3
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First grid is at DC ground. I am not doing any feedback initially so I guess I should be able to connect it directly to ground and then work out resistor values for feedback later.
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Old 6th August 2008, 04:19 AM   #4
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Yes, that grid is a high impedance point, so the resistor values when you do feedback aren't terribly critical. 1k is a reasonable choice, but it could just as easily be 100R.
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Old 6th August 2008, 06:10 AM   #5
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Every now and then I also see it AC coupled to the midpoint of the LTP plates with equal, high value resistors. Haven't seen a theoretical analysis of it though.
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Old 6th August 2008, 07:13 AM   #6
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Why not a cathodyne in front of the LTP ?

Darius
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Old 6th August 2008, 12:34 PM   #7
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Quote:
Originally posted by rdf
Every now and then I also see it AC coupled to the midpoint of the LTP plates with equal, high value resistors. Haven't seen a theoretical analysis of it though.
It's treated in Landee, if you have access to a copy.
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Old 6th August 2008, 01:32 PM   #8
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Quote:
Why not a cathodyne in front of the LTP ?
You mean like Williamson?
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Old 6th August 2008, 01:49 PM   #9
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Quote:
Originally posted by ray_moth

You mean like Williamson?
Yeep,
yes, I made a google search and found this one.


Kind regards,
Darius
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Old 6th August 2008, 06:00 PM   #10
rdf is offline rdf  Canada
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Quote:
Originally posted by SY


It's treated in Landee, if you have access to a copy.
Thx SY. I don't but after a quick search it appears one worth finding.
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