In a message dated 07/01/2008, johnjan@........ writes:

This  image:  _http://jclahr.com/science/psn/as1/as1_dim.jpg_ 
(http://jclahr.com/science/psn/as1/as1_dim.jpg)   shows the construction of the AS-1.  As 
long as the center of mass of the  boom is at the same vertical elevation as the 
boom knife edge 
there will  be no horizontal cross-axis sensitivity.


Hi Dick,
 
    One setup instruction seems to be missing from  the current AS1 manual. 
    
    When you have added load washers to the vertical  bolt to level the arm 
for your particular spring / mass combination, you should  then dismount the 
arm and hang it ~vertically (without the spring) by a  strip of adhesive tape 
from the knife edge / hinge line. You then compare this  to a vertical thread on 
a nut / a plumb line. You adjust the arm to hang  vertically by moving the 
position of the mass balance  washers held between the two clamp nuts. This 
offsets the mass of the  red Alnico U magnet on the lower side of the arm. 
 
    If you don't do this, the C of G will not be level  with the hinge and 
you can get an appreciable sensitivity to horizontal Love  waves. 
 
    As far as I am aware, there is NO comparable method  for setting up an 
EQ1 properly.
 
    Regards,
 
    Chris Chapman



   






In a message dated 07/01/2008, johnjan@........ writes:
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  image:  http://jclahr.com/s=
cience/psn/as1/as1_dim.jpg=20
  shows the construction of the AS-1.  As long as the center of mass of=
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  boom is at the same vertical elevation as the boom knife edge 
there wi=
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  be no horizontal cross-axis sensitivity.

Hi Dick,
 
    One setup instruction seems to be missing=20=
from=20
the current AS1 manual. 
    
    When you have added load washers to the vertica=
l=20
bolt to level the arm for your particular spring / mass combination, you sho=
uld=20
then dismount the arm and hang it ~vertically (without the spring) by a=
=20
strip of adhesive tape from the knife edge / hinge line. You then compare th=
is=20
to a vertical thread on a nut / a plumb line. You adjust the arm to han=
g=20
vertically by moving the position of the mass balance=20
washers held between the two clamp nuts. This offsets the mass of=20=
the=20
red Alnico U magnet on the lower side of the arm. 
 
    If you don't do this, the C of G will not be le=
vel=20
with the hinge and you can get an appreciable sensitivity to horizontal Love=
=20
waves. 
 
    As far as I am aware, there is NO comparable me=
thod=20
for setting up an EQ1 properly.
 
    Regards,
 
    Chris Chapman