Is there a "sweet spot" to which one can adjust the power output for minimum IMD, if so, how would you do it easily? I presume you would need another rx or spectrum analyser. And I bet it changes with antenna reflections, ie from one end of the band to the other.
I dare say a lot of K3s are followed by linears which add even more IMD, so, it might be tricky to optimise for the station as a whole and not just at minimum drive from the K3; perhaps a power pad is needed, but who would bother ? It is hoped that the Elecraft linear might take this into account. David G3UNA ---- Geoffrey Mackenzie-Kennedy <gm4...@btinternet.com> wrote: > Jan Erik Holm wrote on Monday, January 26, 2009 8:52 AM > > As you say, it´s getting rare these days with radios in the > -30 to -40 dB bracket. And we are just going to be content > with it? No not IMO. > > Jan, > > I agree in the context of Amateur Service radios. > > The time might come perhaps sooner than later when it does not matter > whether or not we amateurs are content to put up with poor Tx IMD > performance, somebody else might set the limits for us if we do not. > Although the Amateur Service has been allowed for decades to police itself, > there is growing pressure from some users who have been assigned allocations > adjacent to our bands to clean up what could be called "outside band edge > whiskers" created by amateurs, be they key clicks or IMD products or other > types of garbage. > > Forty years ago in Canada the Type Approval specs for low power HF > transmitters for use in commercial services set the limit for Tx IMD at 30db > below each tone in a two tone test at full rated PEP output. Input to mic > connector, also to any other audio input interface. I must own up to being > involved in writing those specs. However today such a limit does not reflect > what is required by responsible spectrum management nor does it reflect what > can be ahcieved in practice at reasonable cost. We need to look for much > better performance than 30db below test tone. > > FWIW > > 73, > Geoff > GM4ESD > _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
