[Elecraft] Noise going up with reducing XTAL filter BW

[hb9ari]

Tim,

Thank you for info; i will look for
the current filter gain values and adjust
them if necessary.

73 QRO de Rudolf, HB9ARI

Tim Heasman wrote:
> Hi Rudolf,
>
> Just checked the gains on my 1 kHz and 400 Hz filters they are 3 and 8 
> dB. I also checked the audio noise using the dBV display and the noise 
> reduced each time I reduced the bandwidth from 2.8 kHz down to 200 Hz 
> and lower.
>
> Use the K3 utility to check the gains.
>
>
> 73
>
> Tim
>
> gm4lmh
>
> ----- Original Message ----- From: "hb9ari" <hb9ari at bluewin.ch>
> To: "elecraft" <Elecraft at mailman.qth.net>
> Sent: Monday, February 23, 2009 3:44 PM
> Subject: [Elecraft] Noise going up with reducing XTAL filter BW
>
>
>> Hello,
>>
>> Can somebody explain to me why the "audio" noise
>> increase when i select a lower BW XTAL filter?
>> For example going from 1k8 to 400Hz.
>>
>> As i use often BPSK31, the "blue" background
>> of my waterfall (without signal present) go
>> into the "yellow" color; (using Digipan with
>> "standard" waterfall colors).
>> I was expecting a "constant" level or a noise
>> reduction, but not an increase.
>>
>> Is it a Filter gain setting to modify in my K3?
>>
>> Mny tnx in advance!
>>
>> 73 QRO de Rudolf, HB9ARI
>>
>> PS At 66 yo, it's not to late to learn something!
>>
>>
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