[Elecraft] K3 new V3.25 NR not so good for CW week signal

[Merv Schweigert]

http://www.elecraft.com/K3/Roofing_Filters.htm


> What is the best way of determining the gain setting?  Seem to recall an app for this. 
>
> David Wilburn
> NM4M 
> Sent from my Verizon Wireless BlackBerry
>
> -----Original Message-----
> From: Brett Howard <brett at livecomputers.com>
>
> Date: Sat, 15 Aug 2009 15:51:46 
> To: Merv Schweigert<k9fd at flex.com>
> Cc: <Elecraft at mailman.qth.net>
> Subject: Re: [Elecraft] K3 new V3.25 NR not so good for CW week signal
>
>
> Not saying I'd do it.  (and I'm not with the 8 filters I have in my
> radio) but one can if thats what they wish to do.
>
> ~Brett
>
> On Sat, 2009-08-15 at 12:42 -1000, Merv Schweigert wrote:
>   
>> Not really,  if you read the recommendations for the filters you will
>> notice 
>> that caution is warranted for setting the gain higher than
>> recommended, 
>> for IMD prevention if I remember correct.   Kind of like the Inrad
>> roofing
>> filters,  in some cases the gain is set to high and causes more IMD
>> than
>> without the filter. 
>> Some Inrad roofers for the FT-1000D had too much gain and the radio
>> was worse with them installed than without.  W8JI had some
>> measurements
>> on those issues.  
>> Merv KH7C
>>     
>>> This is sorta already there if you have multiple roofing filters.  You
>>> can define the gain that is added when each filter kicks in.
>>>
>>>
>>> On Sat, 2009-08-15 at 13:50 -0600, William Carver wrote:
>>>   
>>>       
>>>> I've noticed in homebrew receivers as the bandwidth narrowed, shedding
>>>> noise and QRM I preferred the gain to go up, increaseing the in-passband
>>>> signal amplitude. I always attributed it to formative years with a
>>>> Heathkit Q multiplier. It may be an effect similar to AGC with
>>>> adjustable flatness (May 1996 analog circuit, in DSP of K3). I found I
>>>> preferred to have strong signals sound louder rather than perfectly
>>>> flat. Prolly a psycho-acoustic explanation (or maybe just get my head
>>>> examined?).
>>>>
>>>> In firmware one could increase the audio gain by an adjustable amount as
>>>> the IF bandwidth was decreased, with an operator-settable scaling
>>>> number. Say 0 = gain independent of bandwidth, to 100 = gain multiplied
>>>> by K * (2800/DSP bandwidth). Very similar to the AGC rise scaling. That
>>>> sounds good to me.
>>>>
>>>>
>>>>
>>>> ______________________________________________________________
>>>> Elecraft mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:Elecraft at mailman.qth.net
>>>>
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>>>     
>>>>         
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:Elecraft at mailman.qth.net
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>>
>>>   
>>>       
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>