Thank you for the post, however I am confused. However, maybe you can help me out with some target numbers.
What is a good IMD report number and good SN number from a receiveing station and what are the numbers that state you are messing up the bands. Lots of contacts kick back and IMD and SN number, as I do with my macros. From my perspective, I can see a trace from someone else and with my filters easily work around it with the K3 no problem, but I can not tell if I am creating a problem with IMD products. I am trying to understand the best way to set up my radio, and when I look at the tables in the link, it tells me that keeping ACL at a maximum of 4 with maybe an ocassional ticke to 5 was the key to a clean signal with a K3 and output power did not matter. Also I have found that there are instances where I can hear DX with the filters tight and for me to respond I have to turn the power up to 80 to make contact. Additionally, I try and find an open spot between frequiences in use and observe to see if I am close to anyone before any TX of any kind. I am amaized but the amount of guys who run with the AFC turned on in their software and they are constantly drifting around and drift close to you and then would be offended that you are interferring with them. Anyway, as stated above, my only feedback on my signal is when someone provides the IMD and SN report, so target numbers would be appreciated as we all have to share the space and contacts. Thanks in advance for your help. Don KD8NNU On Wed, Feb 2, 2011 at 12:13 PM, Kok Chen wrote: > On Feb 2, 2011, at 2/2 1:37 AM, Julian, G4ILO wrote: > >> The most important thing when using PSK modes is not how much power >> you are >> using, but that the signal is *clean*, with the minimum of IMD >> products. And >> that is why with a barefoot K3 or any other 100W radio you should >> not exceed >> about 40W output. > > I agree completely with Julian about this. PSK31 is a weak signal > mode when conditions are good. How much power you need to use depends > on the SNR of your signal at the receiving end. > > Think about it. A 3 dB difference in your signal can only affect the > blocking dynamic range of the receiver by 3 dB. But if your transmit > IMD is 6 dB worse (I have seen some "QRP" signals with -25 dBc IMD), > you are ruining the band for many more people than just your nearby > neighbors who have receivers with poor dynamic range. > > With the K3, there is no practical difference in transmit IMD between > using 20 watts and 50 watts. See the two tables halfway down this > page: > > http://homepage.mac.com/chen/Technical/K3/Digital/digital.html > > In practice, it is non-productive to run power once your SNR at the > receiver is over 0 dB in a 300 Hz noise bandwidth. When there is > multipath, PSK31 will not get through no matter how much power you > use. Even though RTTY is 3 dB less sensitive than PSK31 when > conditions are good, it can still get through even flutter if you have > a good SNR at the receiving end (i.e., transmit with more power). > PSK31 will not get through flutter no matter how much power you apply. > > 73 > Chen, W7AY > > > > > ______________________________________________________________ > 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
