[Elecraft] Why no love for the 1khz CW filter?

Don Wilhelm donwilh at embarqmail.com
Tue Jan 31 21:26:44 EST 2017


Andy,

For normal operating, you will not find the 1kHz filter any more 
beneficial than using the 2.7 (or 2.8) roofing filter.
The ultimate selectivity is provided by the DSP bandwidth, and not the 
roofing filter.

The reason for the more narrow roofing filter is to provide isolation 
from nearby strong signals that are within the roofing filter passband, 
but outside the DSP bandwidth.  If strong signals come into the K3 
outside theDSP bandwidth, but inside the roofing filter bandwidth, they 
can cause AGC "pumping" and reduce the overall sensitivity of the K3 
receiver as a result.

If you are operating in contest situations, or trying to respond to DX 
stations who are 'working a pileup', that extra bit of roofing filter 
may be needed, but for more casual operation, save your money.

73,
Don W3FPR

On 1/31/2017 9:07 PM, abullington at comcast.net wrote:
> I just got my new (used) K3/10 in the mail yesterday and have been having a blast with it. It came with the 2.8 SSB filter and the 400 hz CW filter and I have been told by a couple friends on the air who also have K3s that that’s all I need.
>
> But...nature abhors a vacuum. On my filter board. I was thinking seriously of the 1 khz CW filter because I do a lot of rag chewing on 80 meter CW and I would think that filter would cut down the noise a bit and the 500 hz 5 pole filter with the gentler sloping skirts and either the 200 or 250 for when things get really hairy. But maybe I’m off base here because I see very little talk of the 1 khz filter. I would love to hear thoughts on this.
>
> The guys are telling me forget all that and just get the KPA3A so they can hear me better. Which I will do just to quell the griping but I notice they are copying everything I send at 10 watts.
>
> I am looking at all the ideas you guys gave me a few days ago as well and thanks a lot for the suggestions. I think this may be the most fun I’ve ever had with a new rig. It’s just an amazing radio.
>


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