[Elecraft] filters

[Bob McGraw K4TAX]

I prefer the 500Hz filter over more narrow ones.  Less IMD on the RX signal. 

Bob, K4TAX


Sent from my iPhone

> On Dec 31, 2017, at 9:55 PM, K9MA <k9ma at sdellington.us> wrote:
> 
> I use similar settings for CW, with both filters.  I haven't tried DSP bandwidth of 250 Hz with the 400 Hz crystal filter, but based on the filter characteristics, I don't think it would make much difference.  Also, the 250 Hz filter drifts around so much with temperature that it's hard to keep it centered properly.
> 
> Compare the responses here:
> 
> http://www.elecraft.com/K3/K3_filter_plots.htm
> 
> Anyhow, all I'm saying is that even for a pretty hard-core CW contester, I'm not sure the narrow filter is worth the investment.
> 
> Now, my previous rig, an FT-1000D, which is inferior to the K3 in almost every other way, actually has better skirt rejection on CW, but that's with cascaded crystal filters, both of either 500 or 250 Hz bandwidth.  I'm not sure that's because of an inherent limitation of the K3 DSP, or just the filter algorithm chosen (perhaps to limit latency?).
> 
> 73,
> Scott K9MA
> 
> 
>> On 12/31/2017 21:32, john at kk9a.com wrote:
>> 400Hz is definitely my favorite CW and RTTY filter. I also use the 250Hz
>> roofing filter (switched in at 350Hz) when the QRM gets bad, what document
>> shows that this offers little improvement?
>> 
>> John KK9A
>> 
>> 
>> K9MA wrote:
>> 
>> Assuming it's for a K3(s), I don't think you will find the 250 Hz filter
>> very useful.  The response that both Elecraft and I measured shows that
>> the narrow filter really isn't much better.  Were I to do it again, I
>> would only use the 400 Hz ones.
>> 
>> 73,
>> Scott  K9MA
>> 
>>> On 12/31/2017 17:02, doug dietz wrote:
>>> Guys
>>> i ordered a 400hz filter by mistake.  I have use for a 200h or 1k, 18.k
>>>   What ya got
>>> doug49707 at gmail.com  Doug WD8Z
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> 
> 
> -- 
> Scott  K9MA
> 
> k9ma at sdellington.us
> 
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