Posted by
Darrell Bellerive-2 on
Jan 17, 2008; 8:05pm
URL: http://elecraft.85.s1.nabble.com/K2-RX-audio-tp455255p455256.html
I replaced C25 and C26 with .22 uF ceramic capacitors the other evening as
Matti has suggested. It does make a nice difference in the low end.
I have the KAF2 filter and am using the standard SSB filter as constructed in
Rev E of the KSB2 module. The specs state it is a 2.3 kHz filter.
I notice that the coupling capacitors in the KAF2, C12 and C13 are .22 uF
devices.
I can't help but wonder what changing all four caps C25 and C26 on the control
board and C12 and C13 on the KAF2 to .33 uF would do. I don't have enough .33
uF ceramic caps in the junk box or I would try it. Perhaps I will remember to
order some from Mouser next time I place an order.
I have some polypropylene caps of the right value, but they are a bit to large
physically to fit. The audio buffs seem to favor these over the ceramic types
as they say they have a better sound to them. Be interesting to see if it
would be noticeable.
73,
Darrell VA7TO K2#5093
On Wednesday 31 October 2007 09:48, Marteinn Sverrisson wrote:
> Hi
>
> While trying to improve the K2 RX audio response specially for SSB,
> I noticed lack of low frequencies, looking at the schematics I find
> the the LP cutoff is abt 640 Hz, determined by C25, C26 and the 5k vol
> pot ( this is wheather using DSP or not).
> By increasing C25 and C26 to 0.2uF (from 0.1uF) the LP cutoff is
> moved to abt 320 Hz. This makes better sounding SSB signals and also helps
> in CW mode when copying low pitch signals.
>
> To lower the LP cutoff, I soldered 0.1uF SMD caps across
> C25 and C26 on the control board. To my ears K2 now sounds better.....
>
> 73, Matti
>
> ps. I use 2.4 kHz X-Tal filter
--
Darrell Bellerive
Amateur Radio Stations VA7TO and VE7CLA
Grand Forks, British Columbia, Canada
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