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On Sat, 18 Jul 2015 17:50:09 -0700, you wrote:
> I made parasitic suppressors recommended by another avid VHF
>guy - a copper strap U, and a 300 ohm resistor straddling the U.
REPLY:
300 ohms is a little high. Most designers use from 50-100 ohms. You
need to fine the "sweet spot" for the value. If it is too high, the
circuit becomes effectively a pure reactance which means high Q and
likewise if the value is too low the same thing - high Q. Either
condition will be ineffective in suppressing the parasitic.
This value is not something you can calculate. Some experimentation
is needed.
Also, you don't need nichrome for the suppressor. It's been done for
decades with plain copper. The choice of values for L and R are far
more important, as are other design issues such as short leads, good
shielding, etc.
73, Bill W6WRT
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