[Elecraft] K3 Softrock Lite

[Jerry Flanders]

Hi, Jo

Did you have to get the KXV3 before using it with the K3, or did you 
find another way to interface the softrock to the K3?

Since the K3 roofing filters (centered at 8215) do not pass much of 
your LO freq of 8204 KHz, I am guessing that you would not have seen 
much effect of the moderately weak LO signal at all in the K3 - did 
you try it before you added the additional isolation stage?

Jerry W4UK

At 10:04 AM 2/17/2008, jo benoit wrote:



>Hello
>,
>
>While
>I
>was
>waiting
>for
>my
>K3
>to
>arrive,
>I
>have
>been
>doing
>some
>experiments
>with
>the
>Softrock
>Lite
>.
>The
>softrock
>lite
>is
>an
>amazingly
>good
>rx
>for
>its
>11
>$.
>I
>was
>interested
>in
>a
>panoramic
>display,
>so
>I
>tried
>it
>out
>on
>the
>TS-850
>.
>With
>a
>35.362
>Mhz
>Xtal
>and
>Rocky
>software
>that
>was
>not
>much
>of
>a
>problem.
>It
>worked
>just
>fine.
>For
>the
>K3
>,
>I
>ordered
>a
>32.812
>Mhz
>Xtal
>.
>I
>read
>here
>that
>more
>isolation
>is
>needed
>to
>prevent
>the
>oscilator
>signal
>(
>8.204
>Mhz
>in
>my
>case)
>to
>go
>back
>to
>the
>K3.
>Someone
>suggested
>the
>use
>of
>a
>HCPL-4562
>.
>First
>I
>measured
>at
>the
>input
>of
>the
>Softrock,
>with
>the
>TS-850
>and
>found
>a
>strong
>S9
>carrier
>at
>8.204
>Mhz
>With
>the
>HCPL-4562
>in
>front
>of
>the
>Softrock,
>I
>was
>able
>to
>hear
>the
>carrier
>on
>the
>input,
>but
>no
>indication
>on
>the
>S-meter.
>That
>should
>be
>enough
>isolation,
>I
>think.
>Then
>I
>added
>an
>extra
>stage
>.
>I
>copied
>the
>schematic
>from
>the
>K2
>preamp
>with
>a
>2N5109
>to
>give
>the
>signal
>from
>the
>IF
>an
>extra
>14
>db
>or
>so
>and
>extra
>isolation.
>I
>still
>could
>hear
>the
>carrier
>,
>somewhat
>quieter,
>and
>see
>nothing
>on
>the
>S-meter.
>The
>whole
>thing
>is
>built
>into
>a
>metal
>box
>and
>shielded
>between
>the
>different
>stages,
>and
>an
>extra
>shield
>between
>the
>HCPL-4562
>input
>and
>output.
>The
>connection
>between
>the
>K3
>and
>the
>adapter
>is
>a
>short
>coax
>cable
>with
>two
>bnc
>plugs.
>When
>changing
>from
>xfil1
>to
>xfil2
>and
>xfil3
>on
>the
>K3,
>I
>noticed
>a
>shift
>in
>the
>display,
>so
>I
>made
>three
>different
>entries
>in
>the
>rocky.ini
>file:
>in
>the
>[Band]
>section
>I
>added
>:
>FL1=8625
>FL2=9700
>FL3=9630
>I
>had
>to
>experiment
>with
>these
>values
>until
>the
>signal
>was
>at
>the
>zero
>mark
>on
>the
>scale
>.
>One
>important
>thing
>I
>overlooked
>was
>the
>fact
>that
>you
>need
>the
>KXV3
>interface.
>It
>was
>only
>when
>I
>was
>building
>the
>K3
>that
>I
>realised
>that...
>:)
>I
>have
>no
>special
>soundcard,
>I
>use
>the
>on-board
>soundcard
>of
>my
>pc.
>It
>works
>fine
>with
>Rocky,
>I
>haven't
>tried
>any
>other
>software
>(
>yet
>).
>
>73
>de
>on5ao
>
>
>K2
># 5237
>K3
># 0324
>
>jo
>benoit