[Elecraft] KX3 Roofing filter question

[Matt VK2RQ]

If you have lots of atmospheric noise, you may have too much gain in your revive chain, and should maybe consider switching off the preamp/switching on the attenuator.

There is also the "NR" noise reduction feature which may be useful. However on CW I find that narrowing the PBT bandwidth cuts out a lot of the band noise. As someone else stated, a roofing filter is not going to help you with this sort of problem; a roofing filter is to protect against strong stations on nearby frequencies so you don't get problems like AGC pumping and undesired mixing products.

73, Matt VK2RQ

> On 25 Mar 2015, at 1:49 pm, Fred Jensen <k6dgw at foothill.net> wrote:
> 
> Joshua,  Probably not.  The ultimate BW of your receiver is set by the DSP and noise power is "sort of" proportional to BW.  The purpose of the roofing filters is to protect the ADC sampler at the head end of the DSP from very strong signals that could drive it to saturation.
> 
> Noise, other than atmospheric and galactic, needs to be attacked at the source.  Like getting rid of your switching wall warts and power supplies.  So long as the atmospheric noise is not saturating the ADC, reducing the DSP BW is the only really effective way to reduce it's impact, and that's a lot easier on CW than on SSB.  Different roofing filters are not likely to make much difference at all unless they're more narrow than your DSP setting.
> 
>> On 3/24/2015 7:24 PM, Joshua Gould wrote:
>> All,
>> 
>> Would the roofing filters help reduce atmospheric noise?  I'm having a heck
>> of a time hearing anything over the S5 noise levels that I seem to be
>> dealing with of late.  But at least it's better than the S9 noise I was
>> getting from switching power supplies under my desk...
>> 
>> 
>> 72,
>> Joshua Gould
>> K8WXA
>> EM89pn
> 
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