> > I need to home brew a legal limit + low pass filter for
> > 30Mhz and below. Does anyone have a schematic
> > and parts list? Any pitfalls to watch out for. I'm
> > killing the TV and the XYL is not enjoying my
> > Rag-chewing sessions!
> >
> > Any help is greatly appreciated!
Remember no matter what you do, you must pick components that
have good construction.
Capacitors must have nearly zero lead length and inductors must
be single layer in-line designs.
Don't use toroid inductors or wire lead capacitors with long leads.
If you don't use the right style of components, the VHF and UHF
filtering will not be anywhere near what you expect.
Layout is also critical, the capacitors and inductors must be laid
out with good RF grounding and low coupling from section to
section.
I've seen many filters like this that had very poor VHF and UHF
attenuation, and one actually made the TVI problem worse. It had
poor case grounding from the filter's chassis to the filter's
removable cover, and the cover acted like a little antenna.
73, Tom W8JI
w8ji@contesting.com
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