[Elecraft] filters

[Joe Subich, W4TV]

On 12/31/2017 10:58 PM, ed at w0yk.com wrote:
 > The actual passband of these two filters is more important than the
 > marketing name.

The "marketing name" on the <Inrad> filters is effectively the -1dB
bandwidth.  The name is derived from their original use in Yaesu rigs
and Yaesu's marketing where there were two filters in cascade and
represents the final effective bandwidth of the cascaded pair.  Plot
the cascaded bandwidth of the Inrad #701/#703 pair (400 Hz), #708/#704
pair (250 Hz) or the #711/#714 pair (1800 Hz) and see how that works.

When one has only the first IF filter, the "cascade" is provided by
the 2nd IF DSP.  In the K3/K3S what does the "WIDTH" display actually
show - the -0dB, -1dB, or -3dB point of the 2nd IF response?  Then,
how does that match with the first IF filter and what is the composite
response.

73,

    ... Joe, W4TV


On 12/31/2017 10:58 PM, ed at w0yk.com wrote:
> The actual passband of these two filters is more important than the
> marketing name.  The "400 Hz" filter is about 435 Hz wide at the -6dB
> points.  The "250 Hz" filter is about 380 Hz wide.  Look at the graphs on
> the Elecraft website.
> 
> Ed W0YK
> 
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of john at kk9a.com
> Sent: Sunday, December 31, 2017 7:32 PM
> To: 'Elecraft Reflector' <elecraft at mailman.qth.net>
> Subject: [Elecraft] filters
> 
> 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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