[Elecraft] K3 Filters for digital work

[Joe Subich, W4TV]

 > I am concerned that the 200 hz might be too narrow for RTTY.

The 200 Hz filter is too narrow (mine measure about 190 Hz at -6dB).

The "250 Hz" filter - nominally 370 Hz at -6dB - is a good match to
the minimum necessary bandwidth for MMTTY, 2-Tone, etc. to function
well (particularly if the DSP bandwidth is set for 400 Hz).

I generally use the 400 Hz filter (435 Hz @ -6dB nominal) with good
results.  If I had the 250 Hz filter I would pair it with the INRAD
500 Hz filter as the difference between the 400 (435 Hz) and 250 (370
Hz) are not enough to be significant.  The 500 Hz and 250 Hz filters
also make good "narrow filter" for PSK31 or JT65/JT9 if necessary to
get rid of strong interfering signals on the "other end" of the
passband.

 > I work some CW but almost no ssb.

If you work no SSB but do work CW and data modes, you might consider
the 1000 Hz ("Wide CW/DATA"), 500 INRAD ("normal" CW/RTTY) and 250
("optimum RTTY") filters.  Unless you do a lot of very weak CW in
very crowded bands (DX contests) and need the 200 Hz for CW, I would
consider 500 Hz INRAD and 250 Hz the best all around combination.

73,

    ... Joe, W4TV


On 11/27/2013 12:58 PM, Dave Barr wrote:
> Which two of the 200/250/400 and 500 hz filters are best for digital
> use, primarily RTTY, both contests and dx.  I understand that for JT-65
> and PSK the standard ssb filter, or even the AM filter is useable.  I am
> concerned that the 200 hz might be too narrow for RTTY.  I work some CW
> but almost no ssb.
>
> 73, Dave, K2YG
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