I wrote:
> TT 1800 - 1400 Hz (in CW mode only, 1900 in SSB)
YT1NT replied:
>Roofing filter has one BW in CW, another in SSB?
I finally figured out what is going on.
Orion always automatically centers the passband
of the roofing filter selected and also automatically
truncates any response below 0 Hz. If you have Spot
Pitch set to X, the upper edge of the 1800 Hz filter
(which is actually ~1900 Hz BW) will be at X + (1900/2).
For example, if I am listening with Spot Pitch = 400,
the upper edge is 400 + 950 = 1350 Hz. The lower edge
is still 0 Hz, making it appear that the filter only
has 1350 Hz BW. In fact it is actually 1900 Hz but
the LF response is truncated below 0 Hz.
At any rate this makes the 1800 Hz filter
a very nice filter to use for rapid scanning in CW such
as when doing S&P in contests.
73, Bill W4ZV
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