Page 16
APPENDIX I
MODEL 1034 PROBE MOUNTING
The Monroe Electronics, Inc. Model 1034 Miniature Probe is intentionally constructed with no mounting
devices, as any such mounting device would serve only to enlarge the physical dimensions. It is,
therefore, left to the user to devise a method of mounting the probe to suit his individual needs and to
realize the fullest potential of the inherently small size.
As supplied, the probe is partially jacketed by a length of irradiated polyolefin shrinkable tubing. This
jacket provides insulation of sufficient dielectric strength that the probe may be hand-held or clamped
using light pressure for use within the operating range of the Model 279 ISOPROBE
®
Electrostatic
Voltmeter.
This tubing is otherwise not essential to the operation of the probe. IT MAY BE REMOVED AND
DISCARDED, IF DESIRED. It must, in fact, be removed if the probe is to be disassembled for any
purpose such as cleaning (in those procedures involving removal of the case). A sharp model maker's
knife may be used to slit the tubing using CAUTION to assure that the cable jacket is not nicked or slit.
If replacement is required, a 2
5
/
8
-inch length of ALPHA FIT221-
3
/
8
or equivalent is recommended.
Apply heat only long enough to shrink the tubing in place as damage to the sensitive electronics and
adhesives within the probe may result from prolonged elevated temperature on the outside of the case.
When devising fixturing for the Model 1034 probe, consideration must be given to the fact that the
normal operating range of the Model 279 ISOPROBE
®
Electrostatic Voltmeter is
3000 volts and that
the probe assumes the potential of the surface under measurement within these limits. The probe,
therefore, must be insulated from other parts of the system.
Choice of insulating materials, although not critical in many applications, should be limited, if possible,
to "leaky" dielectric materials with relatively low volume resistivities (in the general order of 10
10
ohm-
cm) as opposed to those such as polystyrene, which is a very good insulator. Example of "leaky"
insulators are the phenolics. The primary purpose in this is to provide a discharge path for the
insulator which has a short relaxation time. This is especially important in the vicinity of the sensitive
aperture.
The Model 279 is capable of driving a capacitive load of several hundred picofarads without severe
degradation in performance. It is possible, therefore, to attach the probe to some fixed portion of the
apparatus via a metal clamp, so long as the metal clamp is insulated from the remainder of the
apparatus.
In any friction clamp design, the pressure (unit force) on the probe case should be kept low, thus over
as large an area of the case as possible as distortion of the gold plated brass may otherwise occur.
One possible configuration is illustrated in Figure A-I-1.
For general bench use burette or utility clamps attached to a ringstand or similar support may prove
adequate. These are available from scientific supply houses.
An attractive alternative to clamping is the use of double sided adhesive tape or fast-setting
polymerizing adhesives such as LOCTITE* SuperBonder 495 cyanoacrylate adhesive or equivalent
which does not require long setting or curing time and provides a relatively permanent bond.
LOCTITE* is a registered trademark of and is available from:
*LOCTITE CORPORATION
Newington, CT 06111
(208) 278-1280
Содержание ISOPROBE 279
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