>
>In many commercial high power tube amps the ceramic caps in the tune
>and load circuits are small value, paralleled up to create a bigger
>value. Is this because smaller values drift less? Thanks.
>
>--
> Best Regards,
> Chris Wilson.
It is about reducing drift, but it isn't quite that "smaller values
drift less".
The main reason for using smaller values is to share out the RF current
between several capacitors. As the heat losses and temperature rise are
proportional to I-squared, using two capacitors of half the original
value will reduce the drift by a factor of 4, or three capacitors will
reduce it by a factor of 9.
However, it is also important to use capacitors with a low temperature
coefficient (NP0 ceramic caps or large silver micas) and it's true that
these are more easily obtainable in smaller capacitance values.
73 from Ian GM3SEK
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