Re: K3 for CW


Rob Sherwood
 

The Ten-Tec Orion was the first to go back to a relative low first IF with roofing filters, followed by DSP I think in 2004.  Then in 2008 the K3 overwhelmed the Orion II.  Rob, NC0B


On Oct 3, 2020, at 7:15 PM, K9MA <K9ma@...> wrote:


Hi Mike,

There's no doubt that the crystal filters greatly improve the dynamic range of the K3. The dynamic range of the DSP is inherently limited by the resolution of the A/D converter, though they are getting better. I think Elecraft was one of the first to combine the benefits of crystal filters with the DSP, with excellent results. I'm looking forward to seeing test results for the K4.

73,
Scott K9MA

On 10/3/2020 7:47 PM, Michael Kopec via groups.io wrote:
Hi Scott. The filters are roofing filters and really only take over on strong 9+ sigs while the dsp handles the weaker sigs. Elecraft has/published an article on this. 73 de Mike K8NS
On Saturday, October 3, 2020, 08:26:09 PM EDT, K9MA <k9ma@...> wrote:


If you look at the published curves for the two filters, you will see that the skirts of the narrow one aren't really much better than the wide one. So, even with the narrow filter, below 400 Hz, the DSP is doing most of the work.

73,
Scott K9MA

On 10/3/2020 5:44 PM, Steve VE3RX wrote:
I agree with Thomas. While I'm not a real "CW" operator, I do use it during some contests. I have the 400 and 250, 8 pole filters. I find the 400 is usually good enough, and with the DSP bandwidth width, I can trim down the bandwidth from there. Once I hit 250, it is real tight and I find not too much better than the DSP turned down to 300Hz with the 400 filter. That said, the odd time, I do need 100-150Hz or so for some real tight DX with pileups, it does help. The only thing I don't know is how different it would be with 400Hz filter and DSP turned down to 100Hz vs a 250 filter and DSP width turned down to 100Hz.
I think you will be happy with a 400 filter, to start with. You can always add another filter later if you feel up to it. There is not a lot of difference in bandwidth between the 250 and 400Hz (8 pole) filters, maybe about 65Hz at -6dB. Not sure of the difference with the 5 pole filters.

73
Steve

73
Steve


-- Scott  K9MAk9ma@...


-- 
Scott  K9MA

k9ma@...

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