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
