[Elecraft] [K2] Filters attenuation

[Mike Harris]

Hi Don,

I'm not concerned in the slightest, it is to be expected and was 
just another measured data point in the discussion.

Regards,

Mike VP8NO

----- Original Message ----- 
From: "Don Wilhelm" <w3fpr at embarqmail.com>
To: "Mike Harris" <mike.harris at cwimail.fk>
Cc: "Curt" <rhulett1 at comcast.net>; <elecraft at mailman.qth.net>
Sent: Friday, November 05, 2010 3:12 PM
Subject: Re: [Elecraft] [K2] Filters attenuation


>  Mike,
>
> Your results are not all that abnormal.  Most do not begin to 
> encounter
> attenuation until less than 400 Hz, so yours is slightly worse off 
> than
> normal in that regard - but then I usually consider 2 dB to be 
> within
> measurement error range.
> However, I was concerned about those who said they had significant
> attenuation at 700 Hz.
>
> Even though there is attenuation at the narrow filter settings, 
> the
> filters are still quite usable for combating QRM.  On the lower 
> bands,
> the band-noise is typically high enough that adding more gain is 
> not
> beneficial unless your antenna is inefficient, but on the higher 
> bands,
> running with the preamp on will more than make up for the few dB 
> loss of
> the narrow filter.  In other words, while this is an interesting 
> topic
> for those of us with measuring tools (signal generator and 
> Spectrogram),
> it is not likely to make a huge difference in actual operating.
>
> 73,
> Don W3FPR
>
> On 11/5/2010 1:29 PM, Mike Harris wrote:
>>
>> Measured using Spectrogram ref level for audio peak -90dB.  The
>> sound card in my PC isn't particularly good and this low level
>> eliminates displayed audio harmonics.
>>
>> Filter:
>> 1000Hz -90 (ref)
>> 700Hz -90
>> 400Hz -92
>> 200Hz - 94
>>
>> FWIW.
>>
>> Regards,
>>
>> Mike VP8NO
>>


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