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776 views
03:00 Oct-24-2000

Mario Belo

NDT Inspection
Trenes Buenos Aires,
Argentina,
Joined Jan 2000
7
Doubt

Dear experts:
I would like to know, in what cases I should use the small screw located inside the control of gain of my USM 2?
does it cause some anormality to manipulate it?

Kind regards,

Mario Belo


 
09:25 Oct-25-2000

Udo Schlengermann

Consultant, -
Standards Consulting,
Germany,
Joined Nov 1998
172
Re: Doubt reply by Udo Schlengermann

Hello,

We are proud to see an instrument which is more than 20 years out of production in operation:
The USM2 had a calibrated decibel-attenuator (gain) stepped in 2-dB-steps.
To set an echo from a reference reflector exactly to a reference line an additional uncalibrated gain is necessary, if the 2-dB-steps do not fit exactly.
This uncalibrated gain is changed by the screw inside the dB-knob.
It's right position gives the maximum uncalibrated gain, it's left position the minimum uncalibrated gain.
Usually this uncalibrated gain should be set to its max-position.

Kind regards

Udo Schlengermann
+++++++

: Dear experts:
: I would like to know, in what cases I should use the small screw located inside the control of gain of my USM 2?
: does it cause some anormality to manipulate it?
:
: Kind regards,
:
: Mario Belo




 
02:48 Oct-25-2000

Bill Waldron

Sales
GE Inspection Technologies,
USA,
Joined Feb 2001
2
Re: Doubt : Dear experts:
: I would like to know, in what cases I should use the small screw located inside the control of gain of my USM 2?
: does it cause some anormality to manipulate it?
:
: Kind regards,
:
: Mario Belo

Mario,
This screw gives 10 dB of gain adjustment and does not affect linearity. Its intended use is to provide a means to fine adjust an echo to a reference level.
(As the USM2 attenuator is in 2 dB steps, it may not be possible to get an echo to an exact level. In this case you would use the small screw adjustment to fine tune the gain level.
Bill Waldron


 


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