hrm... I could have swore that there was a set of mods that would allow one to modify the blanking time and what not a bit...
I'm finding it ineffective in power line noise and would like to try and make it more so. However if I end up with the time to do it I'll probably not have enough time nor repeatable enough condx to test a whole lot. ~BTH On Sat, 2009-09-19 at 12:00 -0400, Mike Morrow wrote: > >I remember somewhere on the net reading about some mods to make the > >K1-NB a little bit more aggressive. > > I've never come across anything like that in the almost nine years that I've > had my K1. I've found the KNB1 to be effective on spark-type noise, but > not at all effective on local power line noise. The NB on my old TS-50S is, > in contrast, very effective on that same power line noise. > > The KNB1 has only the OFF, HI, LO noise threshold settings. Obviously, > the blanking is *least* effective in the HI setting since the noise magnitude > has to exceed a higher value to trigger the noise gate, compared to when > the LO threshold is selected. The only construction option provided is > changing D2 from the normal 1N4148 to an LED to raise the threshold in HI > to require an even *higher* noise pulse magnitude before the the noise gate > will trigger. > > The early KNB1 is identcal to the current KNB1, except that it wasn't > provided with a 0.01 uF cap between U1 pin 1 and pin 8. Without that > cap, gosh-awful noise is generated on some frequencies in the 20m > band (at least) as the K1 transitions between transmit and receive. > Anyone whose early KNB1 is without this cap should install it. > > Of course, that cap has no effect on setting the noise gate trigger threshold. > That's determined only by RP1(9-10), RP2(5-6), and D1 when on LO, plus > D2 when on HI. > > BTW, the K1 Quick Reference has for almost a decade now said that the > KNB1 menu selections are OFF, NB1, NB2 instead of the correct OFF, HI, LO. > > Mike / KK5F > ______________________________________________________________ > 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
