PSN-L Message - Subject: Re: SPRENGNETHER 201 LONG PERIOD VERTICAL SEISMOMETER

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 =20 Hmmm....either its my computer malfunctioned or ?, but here I = see my response to Randall showing up below your message above??? James, =20 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. =20 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. =20 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 =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. =20 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. =20 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. =20 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 = amateurs have no vertical whatsoever.... =20 Take care, Meredith =20 =20 =20 =20 =20 =20 =20

Gary

I don't have a picture of my = Sprengnether Vertical=20 Long period seismometer but it is the same one that Meredith Lamb has on = his web=20 page: http://www.ge= ocities.com/meredithlamb/page028.html

Meredith has an incredible collection = of these=20 including the Sprengnether horizonal long period which I also have and = is=20 currently using.

James Allen

----- Original Message -----
From:=20 Gary=20 Lindgren
To: psn-l@..............

Sent: Saturday, August 16, 2008 = 10:50=20 AM

Subject: RE: SPRENGNETHER 201 = LONG PERIOD=20 VERTICAL SEISMOMETER

James,

Are=20 there any pictures of your Prengnether 201.

Gary

From: psn-l-request@............... =20 [mailto:psn-l-request@............... On Behalf Of JAMES=20 ALLEN
Sent: Saturday, August 16, 2008 9:36 AM
To: = psn-l@..............
Subje= ct:=20 Re: SPRENGNETHER 201 LONG PERIOD VERTICAL=20 SEISMOMETER

Thanks = for the=20 additional information

James=20 Allen

----- = Original=20 Message -----

From: meredith=20 lamb

To: psn-l@..............=20

Sent: = Friday, August=20 15, 2008 11:12 PM

Subject: Re: = SPRENGNETHER=20 201 LONG PERIOD VERTICAL SEISMOMETER

James,

Wonderful attitude! One more = thing...sometimes=20 the adjustment nuts, collars etc., have a hex setscrew/s position = lock/s=20 somewhere thereon; look for them, and

release, or tighten down as=20 necessary also.

Take care,=20 Meredith

On Fri, Aug 15, 2008 at 6:35 PM, JAMES ALLEN = <jcallen1@...........>=20 wrote:

Thanks=20 Meredith. I appreciate all the recommendations and tips for = adjusting=20 what I think is a "beautiful piece of seismic equipment". Your = email=20 has re-inspired me to really tackle this challenge. I will let = you=20 know how it turns out.

Many = thanks again=20 for you wisdom and help.

James=20 Allen

----- = Original=20 Message -----

From: meredith lamb

To: psn-l@.............. =

Sent: = Friday, August=20 15, 2008 8:35 AM

Subject: Re:=20 SPRENGNETHER 201 LONG PERIOD VERTICAL=20 SEISMOMETER

On Thu, Aug 14, 2008 at 9:34 PM, JAMES ALLEN = <jcallen1@...........> wrote:

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

James = Allen

Hmmm....either its my computer = malfunctioned or ?,=20 but here I see my response to Randall showing up below your = message=20 above???

James,

It "sounds" like you need to give some more = slack to=20 the top wire (top rear rotating knurled nut) ...just to allow = the=20 frame/mass to come

further down, which then allows the = vertical=20 seismometer boom/mass to get within the true center = range of=20 your

boom range/pointer mechanism. It = normally should=20 be able to range over the entire pointer scale of course. My = wild=20 guess is that the previous

owner/s had the same (which IS entirely = solvable)=20 problem also; but didn't do the necessary=20 adjustment/s.

Remove the coil and dampening coil wires = before=20 exploring the adjustment mechanisms. I don't know what = you've done=20 before; so, all

I can do is text the = below.

At the rear top is a knurled round threaded = wire=20 adjustment which will raise/lower the wire (and which changes = the=20 period). Try rotating that

slowly over whatever reaction range = first....in conjunction with varying the front set screw, which = you'll=20 need to do probably constantly. Its

entirely possible that even a slight partial=20 rotation or more; will get you into a full range of its = indicator=20 pointer.

Another potential "indicator/answer" could = lie=20 in your front single set screw adjustment setting. Try=20 rotating that over a reasonable range

and observe whether the = boom/mass hits the=20 stop at the top the majority of the time. If (the=20 boom/pointer) hits the top stop limit and stays there=20 the

majority of the set screw range = change; then=20 that reaction would might re-affirm you need for more wire = slack as=20 above.

Adjusting both the front set screw and = the top=20 back screw is critical for this "boom/mass balance/pointer = range" or=20 in short; just being able to

see its oscillation movement range. The = whole=20 thing is kind of a crude weight balance with the spring acting as = kind of=20 a varying pivot force.

IF.....you've done all this before (?), and = it still=20 tends to go to the upper range limit/stop....then you might = actually have=20 to unclamp the

compression wire fitting and feed abit more = wire=20 down. Thats a really nasty job, as you'll be physically = fighting the=20 strong spring tension

while trying to place the wire lower and also = be ready=20 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=20 adjustment at the top/back (?), there should normally be some wire = coming=20 out there?

If there isn't any wire....and you're at the = limit of=20 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=20 vertical. I like its long mechanical period; but I hate its=20 temperature sensitivity. All in all, = its

worth fussing with....theres no real = mechanical=20 alternative of course; outside of electronic extension of lesser = period=20 gizmo's. Most

amateurs have no vertical=20 whatsoever....

Take care, Meredith

= =

PSN-L Email List Message