PSN-L Email List Message

Subject: Re: SPRENGNETHER 201 LONG PERIOD VERTICAL SEISMOMETER
From: "JAMES ALLEN" jcallen1@...........
Date: Fri, 15 Aug 2008 17:35:58 -0700


Thanks Meredith.  I appreciate all the recommendations and tips for =
adjusting what I think is a "beautiful piece of seismic equipment".  =
Your email has re-inspired me to really tackle this challenge.  I will =
let you know how it turns out. =20
Many thanks again for you wisdom and help.
James Allen
  ----- Original Message -----=20
  From: meredith lamb=20
  To: psn-l@.................
  Sent: Friday, August 15, 2008 8:35 AM
  Subject: Re: SPRENGNETHER 201 LONG PERIOD VERTICAL SEISMOMETER





  On Thu, Aug 14, 2008 at 9:34 PM, JAMES ALLEN  =
wrote:

    Meredith Lamb or any member using a Sprengnether 201 Long Period =
unit:  There is an scale on the front of mine with the indicator pointer =
that is at the fourth line from the top, which is essentially at the top =
stop, and will normally oscillate to the 6th line from the top.  Is this =
where it is supposed to be or should it be centered on the 20 unit scale =
which after a year of off and on fiddling seems impossible?
    James Allen =20

      Hmmm....either its my computer malfunctioned or ?, but here I see =
my response to Randall showing up below your message above???
  James,

  It "sounds" like you need to give some more slack to the top wire (top =
rear rotating knurled nut) ...just to allow the frame/mass to come
  further down, which then allows the vertical seismometer boom/mass to =
get within the true center range of your
  boom range/pointer mechanism.  It normally should be able to range =
over the entire pointer scale of course.  My wild guess is that the =
previous
  owner/s had the same (which IS entirely solvable) problem also; but =
didn't do the necessary adjustment/s.

  Remove the coil and dampening coil wires before exploring the =
adjustment mechanisms.  I don't know what you've done before; so, all
  I can do is text the below.

  At the rear top is a knurled round threaded wire adjustment which will =
raise/lower the wire (and which changes the period).  Try rotating that
  slowly over whatever reaction range first....in conjunction with =
varying the front set screw, which you'll need to do probably =
constantly.  Its
  entirely possible that even a slight partial rotation or more; will =
get you into a full range of its indicator pointer. =20

  Another potential "indicator/answer" could lie in your front single =
set screw adjustment setting.  Try rotating that over a reasonable range
  and observe whether the boom/mass hits the stop at the top the =
majority of the time.  If (the boom/pointer) hits the top stop limit and =
stays there the
  majority of the set screw range change; then that reaction would might =
re-affirm you need for more wire slack as above.

  Adjusting both the front set screw and the top back screw is critical =
for this "boom/mass balance/pointer range" or in short; just being able =
to
  see its oscillation movement range.  The whole thing is kind of a =
crude weight balance with the spring acting as kind of a varying pivot =
force.

  IF.....you've done all this before (?), and it still tends to go to =
the upper range limit/stop....then you might actually have to unclamp =
the
  compression wire fitting and feed abit more wire down.  Thats a really =
nasty job, as you'll be physically fighting the strong spring tension
  while trying to place the wire lower and also be ready to tighten the =
compression wire clamp.  Its possible that the previous owner/s might
  have cut off the exposed wire coming out of the wire adjustment at the =
top/back (?), there should normally be some wire coming out there?
  If there isn't any wire....and you're at the limit of =
adjustments...you may have to rewire it to give more room/slack of =
course.  We can get
  into that if necessary.

  I have a love-hate relationship with this coil/magnet vertical.  I =
like its long mechanical period; but I hate its temperature sensitivity. =
 All in all, its
  worth fussing with....theres no real mechanical alternative of course; =
outside of electronic extension of lesser period gizmo's.   Most=20
  amateurs have no vertical whatsoever....

  Take care, Meredith












Thanks Meredith.  I appreciate all = the=20 recommendations and tips for adjusting what I think is a "beautiful = piece of=20 seismic equipment".  Your email has re-inspired me to really tackle = this=20 challenge.  I will let you know how it turns out.  =
Many thanks again for you wisdom and=20 help.
James Allen
----- Original Message -----
From:=20 meredith lamb
To: psn-l@..............
Sent: Friday, August 15, 2008 = 8:35=20 AM
Subject: Re: SPRENGNETHER 201 = LONG PERIOD=20 VERTICAL SEISMOMETER



On Thu, Aug 14, 2008 at 9:34 PM, JAMES ALLEN = <jcallen1@...........> wrote:
Meredith Lamb or any member using a = Sprengnether 201 Long Period unit:  There is an scale on = the front=20 of mine with the indicator pointer that is at the fourth line = from the=20 top, which is essentially at the top stop, and will normally=20 oscillate to the 6th line from the top.  Is this where it = is=20 supposed to be or should it be centered on the 20 unit scale = which=20 after a year of off and on fiddling seems = impossible?
James = Allen  
 
Hmmm....either=20 its my computer malfunctioned or ?, but here I see my response to = Randall=20 showing up below your message = above???
James,
 
It "sounds" like you need to give some more slack to the top=20 wire (top rear rotating knurled nut) ...just to allow the = frame/mass to=20 come
further down, which then allows the vertical seismometer = boom/mass=20 to get within the true center range of your
boom range/pointer mechanism.  It normally should be able to = range=20 over the entire pointer scale of course.  My wild guess is that = the=20 previous
owner/s had the same (which IS entirely solvable) problem = also; but=20 didn't do the necessary adjustment/s.
 
Remove the coil and dampening coil wires before exploring the = adjustment=20 mechanisms.  I don't know what you've done before; so, all
I can do is text the below.
 
At the rear top is a knurled round threaded wire adjustment=20 which will raise/lower the wire (and which changes the = period).  Try=20 rotating that
slowly over whatever reaction range first....in = conjunction=20 with varying the front set screw, which you'll need to do probably=20 constantly.  Its
entirely possible that even a slight partial rotation or = more; will=20 get you into a full range of its indicator pointer. 
 
Another potential "indicator/answer" could lie in your front = single=20 set screw adjustment setting.  Try rotating that over a = reasonable=20 range
and observe whether the boom/mass hits the stop at the = top the=20 majority of the time.  If (the boom/pointer) hits the top = stop limit=20 and stays there the
majority of the set screw range change; then = that reaction=20 would might re-affirm you need for more wire slack as above.
 
Adjusting both the front set screw and the top back screw is = critical for this "boom/mass balance/pointer range" or in short; = just=20 being able to
see its oscillation movement range.  The whole thing is kind = of a=20 crude weight balance with the spring acting as kind of a varying pivot = force.
 
IF.....you've done all this before (?), and it still tends to go = to the=20 upper range limit/stop....then you might actually have to unclamp = the
compression wire fitting and feed abit more wire down.  = Thats a=20 really nasty job, as you'll be physically fighting the strong spring=20 tension
while trying to place the wire lower and also be ready to tighten = the=20 compression wire clamp.  Its possible that the previous owner/s=20 might
have cut off the exposed wire coming out of the wire adjustment = at the=20 top/back (?), there should normally be some wire coming out = there?
If there isn't any wire....and you're at the limit of = adjustments...you=20 may have to rewire it to give more room/slack of course.  We can=20 get
into that if necessary.
 
I have a love-hate relationship with this coil/magnet = vertical.  I=20 like its long mechanical period; but I hate its temperature = sensitivity. =20 All in all, its
worth fussing with....theres no real mechanical alternative of = course;=20 outside of electronic extension of lesser period gizmo's.   Most =
amateurs have no vertical whatsoever....
 
Take care, Meredith
 
 
 
 
 
         =20

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