[TenTec] Roof filters

[Bill Tippett]

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?

         Correct....measured using Spectrogram
but I have never received an explanation from
Ten-Tec, although I have asked several times.
There is obviously some other effect going on
because the filter clearly cannot change
bandwidth itself, but the effect is the same.
To measure this, I set DSP BW = 6000 to remove
any DSP effects and use a noise generator with
Spectrogram to view the resulting spectrum for
CW versus SSB modes.

         You can actually hear this without any
measurements.  Listen to band noise in CW when
switching between the 1000 and 1800 filters
(remembering to set DSP = 6000) and you will
hear very little change in the character of the
resulting noise (assuming good ears).

         This is very strange behavior but I
actually like it since the 1800 filter in
CW gives a reasonable BW (1400 Hz) for S&P
type operation in contests.

         Anyone else have any explanations for
this?

                                 73,  Bill  W4ZV