[1000mp] W8JI INRAD roofing filter measurements

[Lou]

Hi Todd,

Perhaps, but comparing QST, W8JI, and Sherwood 2kHz spacing IMD measurements
we see the following:

QST (+INRAD roofing)	79dB
Sherwood (+INRAD)		77
W8JI (+W8JI NB, +INRAD)	76
W8JI (+W8JI NB)		88

In all cases with the INRAD roofing filter we see about 77dB which is ~10dB
above unmodified, but with one datum point, the W8JI NB mod alone is another
~10dB above that.

I haven't studied the circuitry in detail, but the NB is downstream of the
first and second IFs.

BTW, the W8JI mod doesn't fix the NB, it improves RX performance when the NB
is turned off and at its lowest setting in the menus.

Lou W7HV