>I think he is just being stubborn. :>)
>
>There is nothing wrong with running the exciter and power amp at below
>maximum level. As Rich points out "that is the proper way to run them".
>
>The exciter should be loaded and operated at its "best operating point"
>and its pep limited to that amount. The amount of drive applied to the
>amp from that exciter should be adjusted so that the maximum pep never
>drives the amp into grid current. This can be done with an attenuater
>between the exciter and amp as an example.
>
>With a tube like a 4CX1000 it may be an advantage to have a rather high
>impedance bias supply rather than one that is "regulated". As that tube
>is rated at zero grid dissipation, it can stand only the slightest
>amount of grid current. By allowing the bias to increase as grid current
>is attempted protects the grid from drawing excess current.
** Good point, Gary.
>Normal operation should be adjusted so as to never draw grid current.
>
>73
>Gary K4FMX
>
>
>GGLL wrote:
>> I've been following this nice discussion, and want to ask something
>> about Ian's post, ¿what's bad with running exciter at a lower level and
>> to have the amplifier "seriously under-driven"? (it seems to be not only
>> a lower power output matter).
>> My modest guess is something related with operating points due to
>> distortion considerations, is it?.
>>
>> Many thanks and have all a prosperous 2004
>> Guillermo - LU8EYW.
>>
>> Ian White, G3SEK wrote:
>>
>>> R. Measures wrote:
>>>
>>>> ** The grid does not and can not draw current when a competent
>>>> operator sets the grid potential just above the level where it can
>>>> draw grid-current with the max PEP drive that's available.
>>>
>>>
>>>
>>> That is only true if the grid input circuit is guaranteed to be able
>>> to soak up all possible levels of drive without allowing grid
>>> current... but that also has disadvantages: either the exciter runs
>>> flat-out and generates unnecessary IMD of its own, or else the exciter
>>> runs at a lower level and the amplifier is seriously under-driven.
>>>
>>> I truly cannot see why anyone should design (or defend) a
>>> high-impedance bias supply whose voltage regulation will collapse at
>>> the first trace of either normal or negative grid current. What's the
>>> point, when a better-regulated supply is just as easy?
>>>
>>>
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>
>
>
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