[Elecraft] EV664

[Stewart Baker]

Jim,

You might like to view this page of my site where I detail changes to KSB2 
capacitor values to reduce the excessive LF response.

http://homepages.nildram.co.uk/~baker/K2_SSB_Mods_Overview.html

73
Stewart G3RXQ

On Sun, 28 Aug 2005 09:47:05 -0500, Jim Brown wrote:
> 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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