[Boatanchors] Theory Question

[Phil]

Hi Keith,
It's most likely that you'll see this in circuits where RF can be found 
(IF, RF Amp, Mixers, Oscillators and so forth).

A capacitor has two characteristics that come into play here, both 
capacitance and inductance.  The designer may use two different caps 
with different specs tomake sure that a "resonant" capacitor doesn't 
affect the circuit in a negative way.

In fact, sometimes a manufacturer used this anomaly in their design to 
make sure a bypass capacitor did what it's supposed to. I think that 
Philco was one who often did this, and replacing a bypass cap with 
something different DID affect circuit performance.

73 de Phil,  KO6BB
http://www.qsl.net/ko6bb/  (Web Page)

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On 7/29/2015 2:55 PM, Keith Densmore wrote:
> Have a question I know someone will know the answer to.
> Very often in tube bypass capacitors, both b+ and cathode, two caps are used, a
> lower value and a higher value, ie .01 and a .001.
> What is the purpose of this, would not the .01 do the job alone? Never seen
> this addressed.
>
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> Thanks,
> Keith ve3ts
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