Chopper current amplifier for servo valves

Hello guys,

Can someone please suggest me good alternative to this amplifier?

Basically I need input signal 0-20 mA to amplify to 0-200mA (and introduce some dither) and to use it control Woodward actuator.

I'm having problems with this Schneider amplifier and it seems I cannot adjust it correctly, so I suspect that it is malfunction.

Are there any other manufacturers that you would recommend?

Thank you!

I would check this out:
http://www.axiomatic.com/current-converter.pdf

Manufacturer:
http://www.axiomatic.com/

Regards,
Garry
http://www.accautomation.ca

Thank you for your recommendations.

Can you also recommend some DC current source up to 200 mA? Most loop calibrators are 4-20 mA and now I need one quality DC current source from 0 to 200 mA in order to try to troubleshoot the problem I'm dealing with.

Thank you!

use a power supply and connect a ampmeter (multimeter in series

I would do what shooter suggested if you only need a current source that doesn't change but if you need to control the current from a voltage signal then I would use this.
http://www.deltamotion.com/pdf/vc2124.pdf
I know you don't need the negative voltage input and negative current output but this would do the trick and the current can be controlled.

The specifications say +/- 100 ma but there are 2 channels that can be configured in parallel to supply +/- 200 ma.

Thank you for your response guys.
Peter, I'll try to order this converter that you suggest.

I want to be able to record characteristic of EH actuator and I need to be able to change current from 20 mA to 180 mA (or 0 to 200 mA). I need this current to be stable.
I intend to change current in steps 20, 40mA...

Normally I used Fluke 707 process loop calibrator with this chopper amplifier.

However I noticed that this Schneider chopper is very sensitive to noise. It is enough to only touch input wires with my hand to change output from 100 mA to 120 mA and similar (high spikes).

I tested this in the workshop with shielded cable only used on output.

In the control cabinet there is also a shielded cable that is connected to the ground in the cabinet (only one side) but only from output of this current amplifier to the EH actuator in the field, but input signal (0...20mA) is in the cable that is not grounded and its length to PLC card is about 0.5 m in length

In normal operation very randomly there is a sudden step change in the actuator response so I thought that maybe this is caused by the chopper.

So I intend to replace chopper amplifier with another one ( probably IC-DR-11 "Axiomatic")and to have separate loop calibrator (adjustable current source) just to test actuator itself. Right now I can only test the actuator with chopper connected (to amplify signal 10 times) and from time to time but very randomly I can see spikes in output mA.

Of course, I'll install shielded cable for input signal 0...20mA even though it is very short distance and don't know what could be causing the disturbance (if it is external disturbance at all).

Thank you for your suggestions.