[Lowfer] That filter can't be right!!!

[John Andrews]

Bill,

Not sure how bleary you were when typing that message, but the diagram I
have of Lyle's transmitter shows .018 uF, which is 18 nF. The diagram I
posted shows 18 nF. Where did you get the 1.8 nF from?

John Andrews

> I spend about 2 hours tonight reviewing how these filter tables work. I
just
> looked at Lyle's 63uh-1.8nf-63uh filter and it looks like the 1.8nf
> capacitor should be 18nf. Using the table and scaling equations for a 50
> ohm, .25db ripple, N=3, Chebyshev filter, for a cutoff freq of 232k, the
> inductors are 63uh and the capacitor between then to gnd is 18nf, not
1.8nf.
> I set this up in Psipe and the plotted frequency response with 50 ohm
source
> and load resistances and this perfectly matches the expected response.
Then
> I changed the capacitor to 1.8nf and the response became totally whacky!
Now
> it's back to the bench. Results tomorrow.
>
> Bill
>
>
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