[Elecraft] Notch Performance in FW 3.25

[Paul Kirley]

Today I did a comparison of notch and autonotch in FW 3.25.

K3 serial 1322, FW 3.25.  Heterodyne source a 50 microV signal generator on about 7040 kHz.
Mode LSB, tuned off about 1300 Hz from the carrier to give a target for the notch.
NB and NR off, AGC-S, DSP and roofing 2.1 kHz.

After establishing an audio level AFV with the signal gen running, I switched to the dBV
display.  Turning on the autonotch changed the audio tone by -23.4 dBV, while using the
manual notch (after adjusting its frequency for maximum effect) changed the audio tone
by -49.4 dBV.  Thus the autonotch does work in FW 3.25, but not as well as the manual notch.

It is worth mentioning that actual notch effects will differ by less than the 26 dB 
that this experiment produced, due to the presence of noise and the desired signal.
And YMMV due (among other things) to AGC parameters.  Nevertheless, the manual notch is 
noticeably better than the autonotch in ordinary listening on SSB.

Because I didn't perform this experiment with any earlier versions of FW, I can't say whether
this difference is new or not.

73, Paul W8TM