>
>> ? I am not trying to use Thevenin's. I am using the max power transfer
>> theorem, which essentially states that when half of the total P is being
>> dissipated in the generator, transfer of P to the load is max.
>
>Nowhere in the maximum power transfer theorem does it consider
>source efficiency.
? With half of the total P being dissipated in the generator, and half
of the power being delivered to the load R, the efficiency is obviously
50%.
>
>The maximum power transfer theorem simply gives two
>conclusions:
>
>1.) When the magnitude and angle of an impedance connected to
>the terminals of a network is adjustable, the largest power results
>when Z load is the conjugate of the output impedance of the
>network when the load is removed.
>
? Say what?
>2.) When only the magnitude is adjustable, maximum power is
>transferred when the absolute magnitude of the load impedance is
>equal to the network or source impedance magnitude.
>
>As a matter of fact, the Maximum Power Transfer Theorem only
>refers back to Thevenin and Norton models, both of which rule out
>using the model in any application for describing source efficiency.
>In all cases the source is a black box, and the matching process
>does not define anything in that black box including energy
>conversion efficiency.
>
>> >If you do the interchange you will find your 60 percent amplifier
>> >model made by wrongly applying Thevenin's theorem to a PA
>> >suddenly becomes less than 50% efficient with the very same
>> >parameters of operation.
>> >
>> ? I don't see how doing the Thevenin/Norton interchange is going to solve
>> the discrepancy. If the T/N interchange is valid, why not do it twice and
>> we are back to square one?.
>
>The rules say the models are fully interchangeable. If they do not
>interchange, you are misapplying the model. It is not your "right" to
>pick the particular model that gives the results you want to use at
>any given moment, unless you are invent a 300 mpg carburetor for
>a 66 Caddy or a CFA antenna.
>
>> ? True . It has everything to with dissipative resistances -- i.e., the
>> dissipative ESR in the generator and the dissipative resistance of the
>> load. When power in the load is the maximum possible, an equal amount of
>> power will be dissipated in the ESR in the generator. Thus, the
>> efficiency is 50% at max. power transfer to the load.
>
>Georgia Power's generators just went up in smoke.
>
>Seriously, let me use a generator as an example. Assume we have
>a generator with a fixed shaft speed and unlimited torque compared
>to the power we are consuming. If we fix the field winding
>magnitude by opening the feedback loop to the regulator and do a
>load pull on the generator, we will find maximum power is being
>delivered at that fixed field amplitude for an impedance almost
>exactly equal to the load impedance before the regulation was
>removed.
? ¿?
>
>If we increase ZL, voltage rises but current drops faster so net
>power decreases. If we decrease ZL, current increases but voltage
>drops faster. A load pull shown optimum load Z occurs at a fixed
>impedance, which happens (in a well designed system) to be equal
>to the load impedance set by the regulator at any given load
>condition. The alternator or generator efficiency at that point is far
>more than 50%, yet maximum or optimum power is being
>transferred.
? I agree that large stationary generators typically operate at
efficiency percentages in the high 90s. However, optimum efficiency
necessarily means that maximum power is not being transferred-- i.e.,
optimum power transfer is not maximum possible power transfer. .
>.......
>......
>> >If you add an EQUAL amount of
>> >capacitance in series with the grid you shift the resonant frequency LESS
>> >than 50% higher. That would require about 10 pF or so in an 811A.
>> >
>> ? close enough
>>
>> >Adding a few hundred pF barely changes the self-neutralizing
>> >frequency of the tube, when that parameter is properly measured.
>> >
>> ? I agree that the resonance shift is relatively small, however, perhaps
>> it was far enough to decrease feedthough a bit at the anode-resonance.
>
>No, they plainly claim it adds negative feedback.
>
? I am not talking about a published claim. When I was writing "The
Nearly Perfect Amplifier", I discovered that there is a gimmick in the
30S-1 that is not detailed in the published blueprints.
>......
>We could look at the 30L1, but I don't have the values handy
>without digging. Let's look at the SB220 mistake that Kenwood
>also copied.
>.......
>
? I already agreed that the feedback claim was nonsense, Tom.
> ...........
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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