[Elecraft] K3 headphones

[Brett Howard]

So if you're doing C84 and C92 why not also C82 and C90?

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Alexander Ponomarenko
Sent: Tuesday, June 23, 2009 12:54 PM
Cc: elecraft at mailman.qth.net
Subject: Re: [Elecraft] K3 headphones

These caps - near Front Panel Phone Out. C9=C13=100uF 10V
Also add 1uF: "+" to pin 10 U2; "-" to ground. Picture here:
C9 and C13: http://forum.cqham.ru/download.php?id=43285  (big photo)
new 1uF cap: http://forum.cqham.ru/download.php?id=43286  (big photo)

Yes, IF buffer amplifier also have to be modified. Using only
electrolytic caps C84 and C92 not is enough, they must be bypass
by ceramic caps.
Photo: http://forum.cqham.ru/download.php?id=43287  (big photo)
All these modifications are not simply. I think the best way to
settlements of the problems call to Elecraft Tech. Support and Repairs.

73! Alex UR5LAM

Brett Howard:
> Where are these caps?  I see them on page 28 of 52 on the schematics but
> where do they physically live in the unit.  I assume they are on the main
> DSP board.  Also as far as the "grounded 1uF cap" are you talking about
the
> lil decoupling nugget they had sitting there?  Guess it couldn't hurt...  
> 
> Your pictures say after AF and IF amplifier modifications.  What IF mods
did
> you make?
>  
> 
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Alexander
Ponomarenko
> Sent: Tuesday, June 23, 2009 12:16 AM
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] K3 headphones
> 
> I has tried replacing the 10uF caps with 100uF in AF-amp, also in
> data-sheet for LM4811MM we see grounded pin 10 have to add for 1uF cap. 
> The result is excellent with my ProSet.
> Sound clean and deep. Signals became more raised, proturberant, appeared
> "body of the sound", clearly differ the most small details in signals. 
> Such sensation, that earlier the signals got through blanket,
> but now here is they, straight before my eyes, and they proturberant and
> volumetric.
> As my ears as SpectroLab also "sees the difference". You can see my
> plots "before" and "after" same mods.
> 
> before mods:   http://forum.cqham.ru/download.php?id=43281
> after mods:  http://forum.cqham.ru/download.php?id=43282
> 
> before s9 level:  http://forum.cqham.ru/download.php?id=43279
> after s9 level:  http://forum.cqham.ru/download.php?id=43280
> 
> 73! Alex UR5LAM
> 
> Joe Subich, W4TV:
>>> K9AC has recommended replacing the 10 uF caps 
>>> with 220 uF caps which would reduce the corner frequency 
>>> for low impedance headsets to about 50 Hz but since my 
>>> primary headset is the Proset I have not tried it as yet. 
>>>
>>> 73, 
>>>
>>>    ... Joe, W4TV
>>>     
> 
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