PSN-L Email List Message

Subject: Re: filter on ebay
From: BOB BARNS roybar@........
Date: Mon, 07 Aug 2000 10:22:53 -0400


John,
  I use my filter (Rockland 1022F) between my pre-amp and Larry's A/D
board.  I set the low pass filter to a cut-off freq. of 0.1 Hz.  I use
both sections in series to get sharper cut-off.  This very effectively
eliminates the microseism signals which center at about 0.16Hz.  This
arrangeent is good for a long period seis such as a Lehman and
teleseismic events.  It will severerly limit response to near-by events.
  It is not clear from the ebay ad what the lower freq. limit is for
that filter.  You should email the seller before bidding to get the
correct number.
  These audio filters should help reduce interference from the broadcast
station but  is by far the method of choice in handling that
problem.
  Find an amateur radio operator (ham).  We have to deal with RFI
frequently.  You might even contact the local ham club for advice.
Bob Barns KB2IKC


John Tacinelli wrote:
> 
> Looks like the # on the krohn-hite is 401247238.  There are actually 5 K-H filters or oscillators on ebay.  My question is, c
ould this help me filter out my local radio station that I'm picking up on my seismograph? If so, how does one wire in a filter
 like this?  where in the system does it go?  before the preamp? before the amplifier? after the amp but before the serial box 
interface?
> 
> Any ideas on how one of these gets connected up?
> 
> John Tacinelli
> Earth Science Instructor
> Rochester Community and Technical College
> 
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Larry Cochrane <cochrane@..............>