On Thu, 15 Jul 2004 15:26:54 GMT, "Rick Karlquist N6RK"
wrote:

The filters in my article were purchased in 1995.
Note that they are 10.7 MHz, not 455 kHz. Ceramic
filters are alive and well and still available at Digikey and
Mouser.

Rick N6RK

Believe he mentioned a problem that they could go "hydroscopic" in
Australia?



"Andrew VK3BFA" wrote in message
. com...
"Rick Karlquist N6RK" wrote in message
news:gdnJc.93979$Oq2.67677@attbi_s52...
See my article at: http://www.karlquist.com/FCS96.pdf
Toward the end I show some cascaded ceramic filters.
You can't necessarily just cascade them directly. Of
course it would be ideal to have buffer amplifiers in
between stages, complete with impedance transforming
stages, since the filters usually don't work with 50 ohm
terminations. However, as you can see in the article,
there are shortcuts.

Rick N6RK
www.karlquist.com
www.n6rk.com


How old are these filters - there was a design here in 1971 (The
Deltahet, using the Wadley Loop priciple) based around Murata 455KHz
filters - quite impressive specs, variable bandwidth, etc. Trouble was
the filters went hydroscopic fairly quickly, and I note that there are
very few (at least here) ceramic IF filters now available.
73 de VK3BFA Andrew



---
J. M. Noeding, LA8AK, N-4623 Kristiansand
http://home.online.no/~la8ak/c.htm