SB 200 cont.

[Mark Graalman WB8JKR]

  Hi John,

  The one major problem with the input circuits on the
Heath amps is the network Q is too low. That's why
you can't find a proper point in tuning and it doesn't
provide a Z match. Just for the sake of trying, I would
install a 47 pf capacitor from L1 (coil CA) lug 1 to
ground, and change the output capacitor C36 from 68 pf
to a 56 pf, and retune the coil. You may have to remove
one turn from the coil, or spread the turns. You
could even use a small 10-100 pf trimmer in the place of
the output capacitor C36

  I think this will provide a start point for you to get the
input match down.

73,  Mark  WB8JKR


On Wed, 31 Oct 2001 19:09:55 EST John Barkow <KD6PT at AOL.COM> writes:
> Hi gang.  Thanks for all the help and suggestions.  The problem still
> hangs
> on.  I cannot adjust the 10 meter input coil for center frequency.
> No mater
> where I tune the slug, it does not change.  I replaced the input
> cable with a
> 4' cable as stated in the manual but this has no effect.  The 68uuf
> capacitor
> seems okey and can find no shorts or opens. There doesn't seem to be
> any
> modifications in the input  circuit of any kind.  It is really no
> big problem
> since my TS 570 will tune it okey.  It is just the necessity of
> having to
> re-tune when I switch the amp on.  The other bands work fine, even
> 12,17 and
> 30 meters since the input circuits are very broadbanded.  If anyone
> knows of
> something I haven't tried, let me know.  Again, thanks for all the
> help and
> usefull suggestions.
> John kd6pt
>

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