K3 NB problem
Locked
 
|
I discovered the source of a “noise” I was complaining about on 80M cw this AM. I finally noticed that it would always come on at exactly the time VK9WA said “UP”!! and varied in intensity and duration until he answered someone..at which time the noise was gone and S meter returned to S1!! Seems like the NB settings on the K3 are causing IMD and phase noise from the pileup up the Band a bit to sound like rain static and jump to a level of S5-6 on the K3 meter! Never ran into that before with a K3... Then again, except for this new electric fence pulse, I never needed to use the NB for anything at this previously dead quiet location. Any ideas on what settings I should use or try for this electric fence noise? Possibly the settings that I am using are too aggressive and would cause this?
Regards Larry K1UO ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
|
|
I run across this same situation when trying to copy weak signals in the
QRP Fox Hunts. I rarely use the NB here so it usually surprises me when it happens. The K3 NB is made up of two parts: IF and DSP. For the IF NB, the spectrum is sampled ahead of the roofing filter and is quite broad. This allows the IF NB circuit to take out very short pulses. But when there is a strong signal (or many in the case of VK9WA) in that bandwidth it will cause what you are seeing. The strength of the effect somewhat depends on the IF NB level setting. The DSP NB, of course, is implemented in the DSP code which is after the roofing filter so it's not as susceptible unless the strong signal is inside the roofing filter passband. So if you can select a narrower roofing filter the effect will pretty much go away. Incidentally, this effect isn't unique to the K3. I've noticed it in my other receivers as well. 73, Brian, K0DTJ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
|
Administrator
|
In reply to this post by k1uo-Larry
Hi Larry,
For the IF NB I usually use a level of 3, or 4 max, with a narrow typically for the width. This generally works quite well for me with minimal intermod. More aggressive thresholds and wider widths significantly increase the likelihood of nearby strong signal intermod with IF based NBs. As another poster mentioned, the DSP NB can be cascaded after the IF NB, or just on its own. So trying different combinations of these may also help in your situation. Eric /elecraft.com/ On 11/20/2015 3:00 PM, Larry - K1UO wrote: > I discovered the source of a “noise” I was complaining about on 80M cw this AM. I finally noticed that it would always come on at exactly the time VK9WA said “UP”!! and varied in intensity and duration until he answered someone..at which time the noise was gone and S meter returned to S1!! Seems like the NB settings on the K3 are causing IMD and phase noise from the pileup up the Band a bit to sound like rain static and jump to a level of S5-6 on the K3 meter! Never ran into that before with a K3... Then again, except for this new electric fence pulse, I never needed to use the NB for anything at this previously dead quiet location. Any ideas on what settings I should use or try for this electric fence noise? Possibly the settings that I am using are too aggressive and would cause this? > Regards > Larry K1UO > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
|
|
Eric,
A great update to the K3/K3s would be a fully adjustable IF NB Width control. The available choices now are NAR/MED/WID with 7 degrees of level. Electric fences are wide pulse. I have observed that width vary based on the manufacturer and the quality of the installation; read - all terrible! This is almost exclusively due to inadequate (_non existent_) grounds, bare wire nailed to tree trunks, wire connections that are not really connections at all and the inevitable brush/branch/grass growth along the wire paths. All the JA manufacturers since the 1970s built 40lb primary station radios with noise blankers set to eliminate automobile ignition noise! ICOM with their IC-781 in the late 1980s added a width control along with the level control. Besides my K2 & K3 I have an ICOM 7600. The latest iteration of it's menu system allows adjustable NB level 0-100%, depth 1-10 (still not sure what it does; I leave it at 4) and width adjustable 0-100. With the NB Width control set half way at 50, I can eliminate the pulsing with a Level setting of 50%. If I try that on 160/80 CW chasing DX the pileup will blow the IF away. Increasing the Width to 75 and reducing the Level to 20% the fence pulsing is close to non existent but the pile up is not overloading the IF. Ralph W1ZK ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
|
|
In reply to this post by Eric Swartz - WA6HHQ
I experienced the same phenomenon as did Larry. Some of this was the "fault"
(i.e. normal operation) of the noise blanker; some of it was due to the absolutely abysmal quality of too many of the signals. Regrettably, there were probably some K3s contributing to the mess if some recent QSOs I've had with other owners are any indication. Although I often get unsolicited kudos for my audio, I recently had a 17-meter ragchew with a W6 transplant in GA whose K3 sounded simply awful and looked it on the spectrum scope. Regarding the K3 NB, frankly, I wonder why, with a radio with so many "smarts" built in, we have to adjust I-F NB parameters at all. Setting the threshold automatically, under most conditions, should be automatic and extending the blanking pulse width to match the noise impulse duration should be trivial. See: http://k6mhe.com/n7ws/Noise_Blanker.pdf for some ancient work. (I actually wrote this paper as a final exam for a technical writing course I took. We were told to write something suitable for publication, including letters of submission and a release from the company I worked for. I said to myself, "Self, you've done all of the work, why not just for the heck of it submit it to a ham radio publication? Since the company only gave "published papers awards" for peer-reviewed publications, I figured I really didn't require their approval so I sent it to Ham Radio Magazine and they paid me instead. A couple of years later a guy said to me, "I see your circuit was published in Bill Orr's Radio Handbook." First I knew about it. One would think that a guy who stole your work would at least give you a free book; but no.) On 11/20/2015 8:00 PM, Eric Swartz - WA6HHQ, Elecraft wrote: > Hi Larry, > > For the IF NB I usually use a level of 3, or 4 max, with a narrow typically > for the width. This generally works quite well for me with minimal intermod. > More aggressive thresholds and wider widths significantly increase the > likelihood of nearby strong signal intermod with IF based NBs. > > As another poster mentioned, the DSP NB can be cascaded after the IF NB, or > just on its own. So trying different combinations of these may also help in > your situation. > > Eric > /elecraft.com/ > > On 11/20/2015 3:00 PM, Larry - K1UO wrote: >> I discovered the source of a “noise” I was complaining about on 80M cw this >> AM. I finally noticed that it would always come on at exactly the time VK9WA >> said “UP”!! and varied in intensity and duration until he answered >> someone..at which time the noise was gone and S meter returned to S1!! Seems >> like the NB settings on the K3 are causing IMD and phase noise from the >> pileup up the Band a bit to sound like rain static and jump to a level of >> S5-6 on the K3 meter! Never ran into that before with a K3... Then again, >> except for this new electric fence pulse, I never needed to use the NB for >> anything at this previously dead quiet location. Any ideas on what >> settings I should use or try for this electric fence noise? Possibly the >> settings that I am using are too aggressive and would cause this? >> Regards >> Larry K1UO ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
«
Return to Elecraft
|
1 view|%1 views
| Free forum by Nabble | Edit this page |