[Elecraft] 700 Hz roofing filters

[Bill W4ZV]

Barry wrote:
> 
> 
Personally, I follow the K3ZO school of filtering.  I prefer using my
neuronal network for filtering, especially when running in a contest.  As my
operation is mostly CW, I have the stock SSB, the 1 kHz, and 400 Hz filters. 
I find myself using 1 kHz most of the time and have always done it this way,
going back to my Drake R4B days.  I suspect Wayne got a better deal on his
filter options than I did :.)
73,
Barry W2UP


I can do that on 10m but you won't get away with it on a crowded band.  I
once had a 1 kHz filter but quickly discovered in casual DXing on 160m that
adjacent signals were pumping my AGC.  I prefer a low pitch for weak signal
DXing (my preference is 270 Hz but the K3's 300 Hz is acceptable).  Because
the K3's MCU shifts roofing filter passbands such that the low end always
cuts off at 200 Hz, if you use a 1000 Hz filter with a 300 Hz pitch, the
actual passband is 200-1200 Hz, so a signal 900 Hz away (1200-300) will pump
your AGC.  If you use 500 Hz pitch, the passband remains 200-1200 Hz, so a
signal 700 kHz away will pump the AGC.  In a crowded contest or large
pileup, this simply doesn't cut it.

73,  Bill


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