Very interesting. I was operating at our local submarine for Museum Ships Day, using my K2 in the field about 200 yards away from the sub from which they were operating SSB on 20 meters. I tried to operate 20m CW but the "whooshing" on the band anywhere in the CW segment was just too much. I thought it was just blow-by of the K2's xtal filters, but I think now I'm learning it was the dirty transmitter they were using - not sure which one.
Chip AE5KA On Thu, Sep 13, 2012 at 12:18 AM, Matt Zilmer <mzil...@verizon.net> wrote: > My case study may not be any less interesting than others you've > heard. During Field Day, 2011 K3 #24 (mine) was the centerpiece of > our group's CW effort. The group was a number of aligned clubs, and > we operated 12F (emergency operations center, 12 stations). You can > imagine the HF overlap involved, since there were nearly always two > stations on one band but on different modes. Our site was about 350 > meters in diameter with stations around the outside edges and a couple > on VHF/UHF in the middle. > > Dave, W3DMA, is also a K3 owner. He and I were partnered on the CW > station. We operated 19 hours out of the 24 allowed, for about 800 > contacts. This isn't awful, but it should have been better. The main > cause of our CW count being so low was phase noise from other stations > on the same band at our site. Many were running > 100W too. That > WHOOSH Wayne mentioned wiped out a lot of received transmissions on > our end, and we had to constantly ask for AGNs due to a transient high > noise floor. We could see that 15-20 dB rise of the floor on the P3 > quite easily. The screen went mostly white during those times. > > Now - I KNEW better, but I went around to the other stations when they > were operating on same bands as the CW station (Dave at the key, were > at the computer). They weren't hearing us AT ALL and didn't even know > we were on the same band! Except for our roving spotter with a > broadband panadapter who could see my K3 but not hear it. No key > clicks from us, but of course you could hear them all over the band(s) > from remote stations. > > Phase noise and key clicks are the enemy. I respectfully suggest that > Wayne emphasize (as well) that designing a transceiver to > intentionally not produce either of these is a worthy objective more > on a moral plane than an operating advantage. Tactically, having > clicks and wideband noise could be put to advantage against other FD > groups. As Wayne pointed out, phase noise may limit receiver > sensitivity (if it's not limited first by other factors), but most > hams have never thought about it that way. I suspect, in practice, > that in other transceivers phase noise is not the limiting factor in > sensitivity - mainly because the front end design is shoddy compared > to the K3. Front end noise figure is perhaps a larger factor in many > cases. > > The main real-world problem is that the K3 is a minority in the > general ham rig population. Maybe someday, the K3 penetration rate > will be high enough that we can hear it in how quiet the bands are. > Crowded but quiet between signals that is. > > 73, > Matt Zilmer, W6NIA / NNN0UET / NNN0GAF THREE > NMCM RMS Winmor: NNU9ET-5: Upland, CA. > NAQCC: 6081, 10-10: 10413, KX3 #6/FT > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@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@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
