QRM/QRN - normal?
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Greetings,
I'm currently seeing a consistent S5 for noise level on 20m with the pre-amp activated. It drops to S3 with the pre-amp disabled. This reading was taken at noon time on the east coast. Does this sound reasonable based on current conditions, or do you think I'm experiencing interference from something nearby? I'm fairly new to HAM radio so I'm not really sure what to expect for this time year and based on current conditions. It seems kind of high to me. Thanks, - Bill |
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KB1PXD wrote:
> Greetings, > I'm currently seeing a consistent S5 for noise level on 20m with the > pre-amp activated. It drops to S3 with the pre-amp disabled. This > reading was taken at noon time on the east coast. Does this sound > reasonable based on current conditions, or do you think I'm experiencing > interference from something nearby? I'm fairly new to HAM radio so > I'm not really sure what to expect for this time year and based on > current conditions. It seems kind of high to me. This is probably primarily man-made noise from nearby (radius of a few blocks) electrical devices. You don't mention what rig you are using, but if it has a noise blanker, it might help. This time of year with everyone running air conditioners, it's unfortunately not surprising to see a high noise level in urban or suburban locations. Horizontal antennas will probably be quieter than verticals. Balanced antennas are usually better than unbalanced ones, and dipoles can benefit from the use of a balun. A random wire that comes into your shack is probably the worst of all. -- 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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Hi Vic,
I'm using the K3. I haven't really played much with the noise blanker up until now, but I was just able to reduce the noise level by about 1-2 s-units by enabling NB with the following settings: DSP - T3-7 IF - NAR1 If I couple these settings with disabling the pre-amp, I can get the noise level down to around an S1! Great work Elecraft! I'll have to start playing around with the NB settings more often going forward. I'm not sure what effect this might have on a received signal however. (didn't test that yet) Are there any general guidelines for using NB? (i.e., DSP versus IF, using only DSP, using both, etc.) Thanks, - Bill
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In reply to this post by KB1PXD
Sounds about right to me Bill. That is about what I
get using 2.8 bandwidth. It goes down some if I narrow the bandwidth. Cookie, K5EWJ --- KB1PXD <[hidden email]> wrote: > > Greetings, > I'm currently seeing a consistent S5 for noise level > on 20m with the > pre-amp activated. It drops to S3 with the pre-amp > disabled. This > reading was taken at noon time on the east coast. > Does this sound > reasonable based on current conditions, or do you > think I'm experiencing > interference from something nearby? I'm fairly new > to HAM radio so > I'm not really sure what to expect for this time > year and based on > current conditions. It seems kind of high to me. > > Thanks, > - Bill > -- > View this message in context: > > Sent from the Elecraft mailing list archive at > Nabble.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 > _______________________________________________ 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 KB1PXD
KB1PXD wrote:
> DSP - T3-7 > IF - NAR1 > I'll have to start playing around with the NB settings more > often going forward. I'm not sure what effect this might > have on a received signal however. (didn't test that yet) > Are there any general guidelines for using NB? (i.e., DSP > versus IF, using only DSP, using both, etc.) Whatever works best is good. I have lots of local manmade noise and I find that DSP T2-6 and NAR3 seems to work pretty well. You want to find a setting that will produce the best noise reduction with acceptable signal distortion. In a contest or pileup situation when there are lots of strong signals the optimum setting may be less aggressive. -- 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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>>DSP - T3-7 >>IF - NAR1 > >>I'll have to start playing around with the NB settings more >>often going forward. I'm not sure what effect this might >>have on a received signal however. (didn't test that yet) >>Are there any general guidelines for using NB? (i.e., DSP >>versus IF, using only DSP, using both, etc.) > >Whatever works best is good. I have lots of local manmade noise and >I find that DSP T2-6 and NAR3 seems to work pretty well. > >You want to find a setting that will produce the best noise >reduction with acceptable signal distortion. > >In a contest or pileup situation when there are lots of strong >signals the optimum setting may be less aggressive. I've found that being too aggressive on the DSP NR settings interferes with my ability to hear complete dits on weak CW signals. I'll get part of a dit and sometimes miss hearing the dit if the NR is too aggressive. Dahs aren't a problem to hear at all. This is while using Extreme Isolation headphones. http://www.extremeheadphones.com/ I have tried the method suggested on this list of turning AGC off, turning down the AF gain, turning down the RF gain, and controlling audio level with the RF gain. I usually run the BW at around 200 to 300 cycles for weak CW signals, and around 100 or 50 cycles for strong CW signals. That combination works amazingly well. Of course, with the AGC off, I can't use NR. But I do have the narrow BW. If I want to use NR, I have to turn on the AGC, and I can't tell much difference if any between slow and fast. Then I use the lower NR settings, especially for weak signals. At my relatively RF-quiet location, the NB doesn't appear to make any difference, and it shouldn't. (500 cycle roofing filter installed.) Playing with these settings while copying weak signal CW on 80m or 40m is a pretty good test. As others have noted, you can sometimes hear CW more clearly down in the noise by changing the sidetone frequency. I haven't found any DSP solution to QRXYL yet. But any suggestions are always welcome. This is really interesting stuff and the K3 is quite configurable. YMMV Paul N4LCD _______________________________________________ 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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