To: | cq-contest@contesting.com |
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Subject: | RE: [CQ-Contest] several contesting questions |
From: | Bill Tippett <btippett@alum.mit.edu> |
Date: | Fri, 21 Nov 2003 09:42:41 -0500 |
List-post: | <mailto:cq-contest@contesting.com> |
K0HB wrote: >In a contest radio, you look first for a bullet proof receiver (or as close as you can get to bullet proof). The two key things which will make or break a good contest radio are a good noise floor (MDS) and adjacent channel blocking (BDR). ARRL has a spot someplace on their web with all the results from their lab tests. If you see a "good deal" on a certain radio, go there and check out the numbers. In my experience, the CQ magazine reviews are mostly fluff without good technical support. Steve, I generally agree with Hans but would also consider IMD Dynamic Range with 5 kHz interfering signal spacing as a good measure of how very close strong signals may affect what you hear in your passband. IMHO, this is more important than MDS, since most current radios have nearly equivalent MDS performance. MDS becomes even less important if your noise floor is raised by adjacent station QRM. Here is a good summary by Elecraft of ARRL measurements for recent radios. BDR and IMDDR3 measurements at 5 kHz (4th and 6th columns from the left) are what you should look at. The IC-746Pro is not listed but is likely similar to the 756Pro2, since I believe they have similar front-ends. http://www.elecraft.com/K2_perf.htm (see first Table on this page) If you are looking at older radios, here is another good summary, although these measurements were by Sherwood Engineering, not ARRL. Here I would look primarily at the second column from the right which is IMDDR3 at (mostly) 2 kHz spacings. BDR is probably NOT meaningful here because interfering signals are at 100 kHz: http://www.sherweng.com/table.html Here's yet another comparison table by W8JI: http://www.w8ji.com/receiver_tests.htm 73, Bill W4ZV P.S. Unfortunately some very popular contest radios, like the TS-850 are not included in these summaries. --------------------------------------------------------------- The world's top contesters battle it out in Finland! THE OFFICIAL FILM of WRTC 2002 now on professional DVD and VHS! http://home1.pacific.net.sg/~jamesb/ --------------------------------------------------------------- _______________________________________________ CQ-Contest mailing list CQ-Contest@contesting.com http://lists.contesting.com/mailman/listinfo/cq-contest |
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