[sdiy] Unusual BP filter

[KA4HJH]

Check this slightly complicated bandpass filter--it's tuned with an
eight-gang potentiometer:

http://www.metasonix.com/krohnhiteFilter.gif


Some comments from Eric Barbour:

Krohn-Hite 330A sweepable bandpass filter. 1952, all tubes,
FIFTEEN tubes. Very difficult schema to find, very
rare piece of equipment. NEVER used in recording
studios, only in labs. Insane monstrosity.

It's the only way a WWII era engineer could think of.
Four simple first-order highpass filters followed by
four lowpass filters.
It's not even a typical active filter circuit, though there
is some feedback.
It stinks of black-coffee-and-cigarettes thinking. Sort of like
the ENIAC schematics I've looked at. Not elegant but works,
more or less.


Thanks to Dave Wright for the scan.

-- 

Terry Bowman, KA4HJH
"The Mac Doctor"

"There is no Main Street anymore except at Disneyland--and try and buy a
gun there"--Hank Hill