K3 in 160 contest
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Admittedly, current conditions on 160 are the best I’ve
ever seen, but for us poor cousins in the center of the country to be able to
work zone 14, 15 and 16 like 20M was truly fun to hear. The K3 really
shines when you are trying to pull a European out of the hoard of East coast
callers. MANY Bob K5WA _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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Up until now I thought the 500hz filter was all anybody really needed in tough contest conditions. This was partly based on 4 years of experience with an Orion/600hz roofing filter. But I have finally become a "believer" in the narrow cw roofing filter (I've got 500hz and 200hz in my K3 main/sub) after this weekend's contest. I left my K3 at 200hz for a large part of the contest. The K3 performed phenomenally, although QSK subrx audio was a bit noisy due to protection relay switching on/off (Beverage ants are 100-200ft away from tx antenna). 73, Barry N1EU |
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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. Amazing, and thank you Elecraft for my fun in the 160M CQ test. 73 Gary NL7Y |
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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: [hidden email] 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 |
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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" <[hidden email]> To: "Gary NL7Y" <[hidden email]> Cc: <[hidden email]> 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: [hidden email] > 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 _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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In reply to this post by Vic K2VCO
<quote author="Vic K2VCO"> 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." Hi Vic and thanks for the thoughts. Well, this weekend during the 160 Contest, and previous to that, I tried what you and others have suggested. I disabled via the Config menu the 200Hz, then my 500Hz, then my 2.1Hz filters and operated at the same 150 BW described or less. The noise went up and the S/N ratio made copying sigs more difficult. Time and again. I live in a high noise city environment - like S9+10-15 AM mode on 160, S7-9+5 CW/SSB with 2.7 filter on my Inv-L depending upon time of day and nearby electrical demand. It's overall city hash, and not from one point source like a bad powerpole. Done all I can with the local utility company. Spent 10's of thousands on noise nullers, DSP units, and many radios until the K3 came along to save the day for me. I also have a rotatable Wellbrook receiving loop for the second receiver that cuts the noise 3-4 S units compared with the Inv-L. Anyhow, apparently by inserting the narrow 200Hz roofing filter I'm able to reduce to a minimum the hash getting into the receiver chain. The wider the roofing filter, the more the hash for me at least. The DSP narrows the passband, but can't handle the QRN as well as the fixed filter in my situation. True story, and your experience may vary in a quiet environment. 73 Gary NL7Y |
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