Hi
I need to test diode strings with a pulse generator up to Vf=20Vpp, If=200 mA with a 100 ohm load. I just have to measure I am not familiar with diode testing but I need to have a few questions answered:
A) Can I use a Arbitrary Waveform Generator whose output is 10Vpp into a 50 ohm load, 20 Vpp into an open circuit? Would the AWG be capable of supplying 200 mA? In the fixture I measure the VF of the diode string.
b) Can I make one by using a pulse generator and by using an op amp - I'm thinking of the TI THS3091 - to amplify and deliver the 200 mA pulsed to the diode string?
c) Is there a better way? I can't afford to rent the 8114A which has been recommended to me ($1k/month for 3 months).

 

Just a simple mains transformer (say 24VAC secondary), current-limiting resistor and the 'scope will give you a good idea of Vf and reverse breakdown voltage.

 

If you can get by with less than 20V @ 200mA, then the pulse generator will work.
It looks like a 20V source in series with a 50Ω resistor so it will deliver anywhere from 400mA into a short to 200mA into a 50Ω load.
It will deliver 133mA into a 100Ω load.

If you need more voltage, than Alec's solution sounds simple enough.

Do you have measure the voltage with a particular pulse shape or duration?
If so then you could add a BJT or MOSFET buffer at the generator's output to deliver 200mA at 20V.