Hello all,

in my attempts to learn more about RF in general I've been playing with
tuners, downmixers, etc.

My next stumbling block has been filters.

The particular circuit I'm working on needs a 4.5MHz filter. Researching
I've found that they are common in TV/VCR gear, so I figured I could
scavenge a few and play around with them.

Finding datasheets has been very difficult however. I was wondering if
someone here could provide some guidance?

The filters I'd like to play with look like this:
http://www.surplussalespa.com/catalog/product_info.php?cPath=3D&products_id=
=3D440

What's confusing me is the numbers.=20

I have 4 filters on a board for a portable TV in front of me, they are
labelled:
a4.5A (5 pins)
T4.5B (3 pins)
F4.5D (3 pins)
D4.5Z (3 pins)

I understand the difference between the 3 pin and 5 pin parts, but what
do they suffixes (and perhaps the prefixes) mean?

For example, some datasheets I've found seem to indicate that the only
difference between A, B, D and Z are pass bandwidth.

Others indicated for example that the B is a notch filter (although the
surplus site that I linked indicates it's a pass filter?!)

Some describe the filter as a "Ceramic Discriminator", what does that
mean?

Thanks for any help!

TTYL

--=20
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