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 lambSent: Friday, August 15, 2008 = 8:35=20 AMSubject: 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 = AllenHmmm....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 comefurther down, which then allows the vertical seismometer = boom/mass=20 to get within the true center range of yourboom 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 previousowner/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, allI 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 thatslowly over whatever reaction range first....in = conjunction=20 with varying the front set screw, which you'll need to do probably=20 constantly. Itsentirely 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 rangeand 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 themajority 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 tosee 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 = thecompression wire fitting and feed abit more wire down. = Thats a=20 really nasty job, as you'll be physically fighting the strong spring=20 tensionwhile 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 mighthave 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 getinto 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, itsworth 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