[Elecraft] K3 5 pole vs 8 pole filters - attenuation in the passband

[Guy Olinger K2AV]

I find that the biggest use for the "250" filter, which really is ~350, is
to narrow a run station passband when the band gets crowded. These days
that's almost always. I find a place where the "400" really 450, does not
contain other stations, and then operate at 350 Hz bandwidth. I use the
"400" at 450 for casual CW operation. Have to remember that the 250 filter
is the filter that INRAD designed for use in the FT1000MP series, as part
of a cascaded PAIR of filters where the pair was a top shelf 250. The pair
was the 8 MHz IF and 455 kHz IF filters in series.

The "250" 8 pole and the DSP set at 250 work very well together, good
enough for any of my needs. With the "250" defined as 350 in the K3, and
the DSP at 350, you have very sharp skirts eminently useful for crowded
contest work.

73, Guy K2AV

On Sat, Feb 27, 2016 at 11:21 AM, Scott Ellington <k9ma at sdellington.us>
wrote:

> I have both the 8 pole 400 Hz and 250 Hz filters.  For CW, I just haven't
> found the 250 Hz filter that useful.  For one thing, it's not really that
> much narrower than the 400 Hz filter.  I do find that a bandwidth less than
> 400 Hz is sometimes useful in heavy QRM, but I think the 400 Hz filter and
> DSP would be adequate.  If I were to do it over again, I would not buy the
> 250 Hz filter, at least not before trying without in a few contests.
>
> 73,
>
> Scott  K9MA
>
> On 2/27/2016 09:56, lstavenhagen wrote:
>
>> for what it may be worth, the 400hz 8 poles in my K3 and K3S are like
>> brick
>> walls. I haven't yet found a situation where the 400hz filter plus using
>> the
>> DSP to go narrower hasn't covered even the most crowded situations.
>>
>> I'm 99.9986% CW, so that filter is adequate for me but if you're a PSK
>> hound, for example, I could see the 250hz filter. For RTTY, I think the
>> 250hz filter might be borderline, though...
>>
>> Just my thoughts,
>> LS
>> W5QD
>>
>>
>>
>> --
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>
>
> --
> Scott Ellington  K9MA
> Madison, Wisconsin, USA
>
> k9ma at sdellington.us
>
>
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