On Sun, 24 Aug 2008 14:41:54 -0700 (PDT), Barry N1EU wrote: >Why is 50hz important if it is completely outside the passband? +/-16dB at >50hz has zero effect on rx or tx in the K3.
Don't be so sure that there's no effect. It's important that when this undesired low frequency energy is produced by the mic, it is not carried through AUDIO path where it can trigger limiting, create distortion, or even cause overload. On the air, especially during contests, I hear lots of low frequency trash on SSB signals, most of it room noise. In general, if the desired bandwidth of a system is limited, as ours is, the modulating signal (in this case, microphone audio) should be bandwidth- limited as early in the signal chain as practical. Many good mics have built-in high pass filters or low-frequency roll-off filters. When I'm mixing live program material, whether music or speech, I ALWAYS use a good high pass filter on every microphone preamplifier. With most musical instruments, it's set near 200 Hz. With instruments like a bass or bass guitar, I'll move it down to 40 Hz or so. 73, Jim Brown K9YC _______________________________________________ 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
