[TenTec] Why "roofing" ?

[Ynkedragon at aol.com]

In a message dated 08/03/2004 14:35:23 Eastern Daylight Time, Rick at 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