>R. Measures wrote:
>>
>>
>>>On Wednesday 19 November 2003 13:09, A.J Moss wrote:
>>>snip
>>>> If I were to make a floating adjustable regulated DC supply, I could
>>>> use an ordinary pot to control the heater volts, meter it, and have a fine
>>>> adjustment to within ca. 1V either way to set optimum heater volts. I
could
>>>> also then add a current limiting option on the regulator to limit inrush
at
>>>> switch-on
>>>>
>>>> Are there benefits, advantages, or just risks of using such a scheme?
>>>> Constant unvarying power at the heaters seems good, but is 'less' 'more'
to
>>>> use the cliche.
>>
>>>Repays itself in no time at all if you're ever going to operate portable.
>>>
>>** True, but there is no reason to limit inrush-current to heater-type
>>tubes.
>
>Not with a normal small mains transformer, which has some degree of
>built-in current limiting anyway.
>
>But a voltage regulated power supply will do the opposite - it will try
>to push *extra* current through the lower resistance of a cold heater,
>unless there is some kind of current limiting or a slow ramp-up in
>voltage at startup.
** So why not follow the tube manufacturer's recommendation?
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