K3: DSP rev D - now I "get" it

[DOUGLAS ZWIEBEL]

One of the posts that I found confusing and prompted a reply from me
was from Eric:
http://mailman.qth.net/pipermail/elecraft/2009-December/122284.html

Specifically, the 2nd sentence.

------------------------

BUT NOW I've finally put it all together (Okay, maybe I'm a bit slow).
 If you are also confused, I hope this helps (and I hope I've got it
right).  If you're not confused, stop reading now, unless you are Eric
or Wayne in which case you may jump directly to the bottom.

The DSP board revision is modifying component values on the board
itself to expand the low frequency (audio) response.  Elecraft is
using different component changes than those offered by W9AC.  If you
buy the upgraded DSP board, you get the Elecraft changes which
"enhance the low end of audio" (more bass).

On top of that, there is also the LPF board.  This add-on is just what
it says, a Low Pass Filter.  In other words, it knocks out the higher
audio frequencies, which may contains various artifacts ranging in the
5kc to 14kc range (not a range of interest to those involved in ham
communications), while "passing" the low frequency stuff.

If you do not buy the DSP board upgrade, but add ONLY the LPF board on
your own, you will cut-off the higher frequency artifacts (if any).
If this is the "noise" some commented on, this may help reduce or
eliminate that.

If you want to extend the low frequency (bass) elements, you need to
modify the components on the DSP board.  You can either DIY via W9AC
or buy it from Elecraft.

As a "bonus," if you buy the DSP BOARD UPGRADE (swap) from Elecraft,
you get "both" = LPF "add on board" to kill the high freq junk AND the
extended low freq response due to modified component values on the DSP
board.

If you are like me (and many others), you don't hear the high freq
junk (hence, no need for the LPF) and you are already quite happy with
the low freq response (how low a note do you want to hear?), and
THEREFORE, won't buy the upgrade (either the entire board which
includes the LPF board, or just the LPF) and won't implement the W9AC
component mods either.  Clearly, not everybody is "like me."

I have to admit, this was a very tortuous email route to a fairly
simple conclusion.  The emails and announcements along the way were
all very "choppy" and unless you already understood what was happening
(imho), it did indeed seem confusing and perhaps even "conspiratory."
Of course, having dealt with the Aptos guys and their emails for
years, I knew it could not be the latter.  ;-)

MY SUGGESTION TO ELECRAFT:
Besides offering the completed DSP upgrade, for those who are capable,
also offer a "kit" which includes the replacement components for the
DSP board.  So the loyal owner would have three options:
1.  Buy the completed updated DSP board with new component values on
the board AND the LPF board (you already offer this).
2.  Offer just the LPF board (you already do this)
3.  Offer a kit which contains only the components to be swapped out
on the ver B DSP boards (new).

Whew!
de Doug KR2Q
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[Don Wilhelm-4]

Doug,

Personal opinion --
While that seems to be a good suggestion, I don't think it is likely to
happen.  The DSP board has a lot of closely spaced 0603 SMD components.  
I can just imagine the flurry of support questions that would result
from such a kit.  Note that all other K3 mods offered by Elecraft have
both leaded components and SMD parts and the SMD parts to be changed are
not in densely packed areas of a board.  The DSP board appears to be
quite different in that respect - I do not believe there are a lot of K3
owners who have proper SMD rework stations at their workbench, and I
certainly would not try making such changes with normal tools for
working with leaded components.

73,
Don W3FPR

DOUGLAS ZWIEBEL wrote:

> <snip>
> MY SUGGESTION TO ELECRAFT:
> Besides offering the completed DSP upgrade, for those who are capable,
> also offer a "kit" which includes the replacement components for the
> DSP board.  So the loyal owner would have three options:
> 1.  Buy the completed updated DSP board with new component values on
> the board AND the LPF board (you already offer this).
> 2.  Offer just the LPF board (you already do this)
> 3.  Offer a kit which contains only the components to be swapped out
> on the ver B DSP boards (new).
>
>  
>

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