Posted by
Jim Brown-10 on
Aug 28, 2005; 3:47pm
URL: http://elecraft.85.s1.nabble.com/EV664-tp381491p381495.html
On Sat, 27 Aug 2005 10:26:57 -0500, Jim Brown wrote:
>The mods are quite simple. First, change R14 from 1K to 2K. Second,
>change C34 to 0.22 uF. Third, add 2.2uF in series with R15.
A correction to one of my suggested mods by Don, W3FPR, who understands the K2
in far more detail than I do, and emailed me to discuss it. The cap in series
with R15 is a bad idea, for several reasons, based on the control logic for
the compressor. If a cap were to be added there, it ought to be in parallel
with R15, not in series, and it ought to be smaller -- perhaps about 1 uF.
What both caps do is reduce modulation from breath pops and low frequency
noise in your shack. Popping and low frequency boost is a common problem with
directional mics used close up. Even in pro applications, we use a lot of low
cut on these mics, and it is even more important to do so in communications
circuits.
Jim
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