In a message dated 2007/05/04, Paulc@........ writes:

> I have a couple of questions.
> 1) What is the width of your horizontal sensors.  I mean the distance 
> between the leveling legs?

Hi Paul,

       About half the length of the arm. If you make it less, you may find it 
hard to level.

> Mine is 21"  and the boom length is 40"

       Sounds about right.

>  2) This sensor seems very susecptible to tilt and but has yet to record a 
> quake...
> SO is it possible for the "stance" of the machine to be too wide, making it 
> world well as a tilt machine and poorly as a lateral mothin machine.

       No. All Lehmans are sensitive to tilt. What is it resting on?
       Check your period. What is it?
       Check for free swing movement. OK?
       Check the damping is ~ critical and not seriously overdamped. What 
sort of damping are you using?
       Check the orientation with respect to the source? Lehmans may be 
better on transverse Love waves. They DON'T respond equally in all directions! 

>  I can send this info to anyone who might want to look.
> 2) an random 1 hour SAC file so you guys can see the noise floor.

       Check that you are picking up the six second microseisms OK. If not, 
you may need more amplification, or have a wiring problem? What sensor are you 
using?

>  3) A SAC file of the sensor with the coil locked down so you can once 
> again see the noise floor
> 4) A SAC file of  me standing 3 feet away from the sensor, perpendicular to 
> the boom, for 5 secs  so you can see the tilt response.

       If you are getting an OK tilt response when you move in both 
directions, it sounds more like an orientation or sensitivity problem.

       Do you have a photo of the seismometer?

       Regards,

       Chris Chapman   
In a me=
ssage dated 2007/05/04, Paulc@........ writes:



I have a couple of questions.<=
/FONT>=


1) What is the width of your horizontal sensors.  I mean the distance=20=
between the leveling legs?




Hi Paul,



       About half the length of the arm. If yo=
u make it less, you may find it hard to level.



Mine is 21"  and the boom=
 length is 40"




       Sounds about right.



 2) This sensor seems very sus=
ecptible to tilt and but has yet to record a quake...

SO is it possible for the "stance" of the machine to be too wide, making it=
 world well as a tilt machine and poorly as a lateral mothin machine.=




       No. All Lehmans are sensitive to tilt.=
 What is it resting on?

       Check your period. What is it?

       Check for free swing movement. OK?

       Check the damping is ~ critical and not=
 seriously overdamped. What sort of damping are you using?

       Check the orientation with respect to t=
he source? Lehmans may be better on transverse Love waves. They DON'T res=
pond equally in all directions! 



 I can send this info to anyon=
e who might want to look.

2) an random 1 hour SAC file so you guys can see the noise floor.



       Check that you are picking up the six=20=
second microseisms OK. If not, you may need more amplification, or have a wi=
ring problem? What sensor are you using?



 3) A SAC file of the sensor w=
ith the coil locked down so you can once again see the noise floor

4) A SAC file of  me standing 3 feet away from the sensor, perpendicul=
ar to the boom, for 5 secs  so you can see the tilt response.



       If you are getting an OK tilt response=20=
when you move in both directions, it sounds more like an orientation or sens=
itivity problem.



       Do you have a photo of the seismometer?=




       Regards,



       Chris Chapman