[Elecraft] K3 in 160 contest

[Dave Hachadorian]

Maybe NL7Y is on to something here. From previous 
correspondence on the reflector, 60 dB BW of the DSP = 6 dB 
BW + ~300 Hz. So, if you have the DSP BW set at 150 Hz, 
the -60 dB point is about 450 Hz. I can't find plots of the 
200 Hz filter, but I'll bet that the effects of that filter 
and the DSP are additive in this region.

Dave Hachadorian, K6LL
Yuma, AZ



----- Original Message ----- 
From: "Vic K2VCO" <vic at rakefet.com>
To: "Gary NL7Y" <pearse at gci.net>
Cc: <elecraft at mailman.qth.net>
Sent: Monday, January 26, 2009 4:42 PM
Subject: Re: [Elecraft] K3 in 160 contest


> Gary NL7Y wrote:
>>
>> I've found that with the 200Hz filter enabled in both of 
>> my receivers via
>> diversity reception mode, BW set to 150 or less, that 
>> weak sigs pop out of
>> my high S5 city noise floor like the best audio APF 
>> enabled rigs I've owned
>> (many). Elecraft has a Genie of sorts helping us on CW, 
>> and no filter
>> ringing that I care to mention.
>
> Are you sure that the 200Hz filter had anything to do with 
> this? Maybe you would have had
> the same results with a 400 or 500 Hz filter with the DSP 
> bandwidth at 150 or less.
>
> I've seen several comments like this, but keep this in 
> mind: with the DSP bandwidth set to
> 150 Hz the only time you will notice a difference between 
> the 200 and 400 Hz filters is
> when there is a S9+30db signal that is more than 100 and 
> less than 200 Hz away from the
> desired signal.
>
> I made some simplifying assumptions in the above, but you 
> get the idea.
>
> Put another way, you would not notice any difference in 
> performance between a K3 with
> *only* the supplied 2.7 kHz filter and one with a 200 Hz 
> filter unless there is a signal
> loud enough to activate the hardware AGC (about S9+30dB) 
> which is within the filter
> bandwidth but outside the DSP bandwidth.
>
> -- 
> 73,
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco
> _______________________________________________
> Elecraft mailing list
> Post to: Elecraft at mailman.qth.net
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com