In a message dated 08/03/2004 14:35:23 Eastern Daylight Time, Rick@dj0ip.de
writes:
<< Most of the rigs built in the past 15 years had a roofing filter which was
in its first IF, somewhere between 45 and 70 MHz. These were typically only
2-pole filters and wide as a barn door (20 kHz with skirts that were not
very steep). >>
Another reason that these filters had to be broad was to accomodate FM
bandwidth. (Or perhaps the FM mode was offered in more rigs because the "broad
as a
barn door" selectivity allowed the inclusion of an additional mode at little
or no extra cost)
73, Blair k3yd
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