In Reply to: RE: What tubes to use with this Interstage Transformers? posted by megasat16 on September 8, 2016 at 14:38:28:
"Any drop in voltage and current and phase coherence is being compensated by the FG internal circuitry. That is something an external series 5K resistor can't do."
But the whole point is that a signal generator with 5K output impedance will NOT compensate for voltage drop in the way you are saying. If it did, then its output impedance would be lower. The output voltage of a signal generator with 5K output impedance will drop to one half of its unloaded output voltage if it drives into a 5K load. That is what it means to have a 5K output impedance.
If instead the signal generator compensated by means of internal feedback circuitry, so that connecting the 5K external load caused less than 50% drop in output voltage, it would mean that the output impedance of the signal generator was actually, by definition, less than 5K.
A signal generator with unloaded AC output voltage V and output impedance R can be modelled by an ideal zero-output-impedance voltage source with AC voltage V, in series with a resistor of resistance R.
Yes, there are certain approximation issues concerning some possible reactive component to the output impedance of the generator. But I would think that any modern half way decent signal generator will have an essentially resistive (non-reactive) output impedance, at least at low (like audio) frequencies.
And as I said before, if one is making a 5K output impedance (or 5050 to be more precise) signal generator by putting a 5K resistor in series with a 50 ohm output impedance signal generator, the issue of whether the 50 ohm impedance is reactive or not will pale into insignificance when put in series with 5K of purely resistive impedance.
Chris
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Follow Ups
- RE: What tubes to use with this Interstage Transformers? - cpotl 15:01:00 09/08/16 (5)
- RE: What tubes to use with this Interstage Transformers? - megasat16 15:05:55 09/08/16 (4)
- RE: What tubes to use with this Interstage Transformers? - cpotl 15:33:49 09/08/16 (3)
- RE: What tubes to use with this Interstage Transformers? - megasat16 15:37:29 09/08/16 (2)
- RE: What tubes to use with this Interstage Transformers? - cpotl 15:55:04 09/08/16 (1)
- RE: What tubes to use with this Interstage Transformers? - megasat16 16:11:01 09/08/16 (0)