[Elecraft] K3/K3s filter setting with the K3 Utility

[Rich]

Since we are on this topic.  I have a question regarding the 500hz 
filter.   From what I have read it is rated at 525hz.   So would it be 
best configured to come on at 500hz or should I set it to 550hz.  I do 
not think you can set it to 525hz

Thanks in advance

Rich

K3RWN

On 3/22/2019 17:58 PM, Richard Ferch wrote:
> There can be reasons to configure a roofing filter differently from its
> nominal bandwidth.
>
> For example, I have a "250 Hz" filter. According to the filter plots on the
> Elecraft web site, the 6 dB bandwidth of this filter is actually closer to
> 375 Hz. I configured my filter to switch in at 350 Hz, which makes it much
> more useful to me than it would be if I had configured it to switch in at
> 250 Hz.
>
> If this filter is configured to switch in at 250 Hz in agreement with the
> label, then when you set your DSP bandwidth to 300 Hz or 350 Hz, you will
> be using the next wider filter in your receiver. Strong signals outside the
> DSP bandwidth but inside the wider  roofing filter's bandwidth can still
> have bad effects, whereas if the filter is configured to switch in at 350
> Hz, you can take advantage of its ability to reduce those unwanted signals
> with relatively minor impact on signals within the DSP bandwidth.
>
> Of course, if the bandwidth of the 250 Hz filter really was 250 Hz,
> configuring it to switch in at 350 Hz would render the 300 Hz and 350 Hz
> settings of the DSP filter somewhat less useful, since the actual bandwidth
> of the filter combination would now be close to 250 Hz regardless of what
> the DSP control said.
>
> There might be reasons to go in the other direction as well, i.e. to
> configure a filter to switch in only at a narrower bandwidth than the
> bandwidth marked on the filter. For example, if you had 500 Hz and 1000 Hz
> filters and often used a digital mode whose bandwidth was, say, 750 Hz, you
> could configure the 1000 Hz roofing filter to switch in only at 700 Hz and
> below. This would give you better filtering between 500 Hz and 700 Hz than
> without the 1000 Hz filter, while still permitting the 750 Hz mode signals
> to pass through at DSP settings of 750 Hz and above without being
> restricted by the roofing filter.
>
> 73,
> Rich VE3KI
>
>
> KA1J wrote:
>
> Is there any advantage to setting the 1.8
> above, say as 2. in the utility.
>
> Or to have the 200Hz filter engaged at say
> 250?
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