Hi I found analog oscilloscope and function generator locally for good price (as I think it is good). See the photos and the prices and tell me what do you think.
The big pictures in the attachments the seller told me he will power them on and let me test them. 1:- Beckman industrial 9020 oscilloscope 20MHz and 2 CH goes for 70$ 2:- Hung chang HC-L202 oscilloscope 20MHz and 2 CH goes for 50$ there is 2 of them. 3:- Goldstar function generator fg-8002 goes for 30$ there is 2 of them. 4:- Low frequency amplifier da-440 goes for about 45$ (do not remember ) What do we need it for?
(I am beginner so should I get it or not) 5:- I do not know what does it do. Did not ask for the price. I am thinking of getting the Hung chang oscilloscopes because they are tow so I have parts for fixing it if it stoped working.
And the tow function generator. So what do you think?
Beckman Function Generator Fg2 Manually Diagram
How do I test them? If there is self test how do I do it? I,too, would suggest to go with the Beckman Oscilloscope,as it has Delayed Timebase,which is a very useful facility to have in a 'scope.
Beckman Function Generator Fg2 Manually Download
That said,Hung Chang are a legitimate brand,& have been around for quite a long time. 'Goldstar' is LG's old name,& the function generator looks quite reasonable. The low frequency Amplifier looks interesting,but it is a bit expensive,unless you have an immediate use for it. The same goes for the 'NEVA' device. I don't think it is a current source as 'verstarker' means 'amplifier' in German. I think it is some kind of range extension device for a (perhaps some specific?) current meter.
No 'self test' with this sort of stuff! You would normally turn on the Oscilloscopes,see if they have a trace on the screen,apply a signal to the vertical inputs in turn-perhaps from the calibrate outputs usually provided,or from the Function Generator,or even just a bit of mans hum picked up by your body. Once the 'scope seems OK,run the FG through its paces. It is a Measuring Amplifier. The ranges are: Current: 10 -5 A to 10 -11 A ranges Voltages: 100uV to 100V ranges Charge: 10 -7 to 10 -11 Amps-seconds The way the charge measurement works is you record the maximum deflection of the meter needle as the charge is discharged via a resistor in the amplifier. I gather it is valve based, and to get the very low leakage currents, they use valves run with the heater at 4V instead of 6.3V and the anode at 40V. It is all stuff that can be done far more easily now with a cheap opamp circuit.
At a guess, it is probably not super accurate. Since a typical meter movement or VTVM (Vacuum Tube Voltmeter) was accurate to about 3%, a 1% accuracy is about as much as I would expect.
At the time though, to be able to measure down to less then a nanoamp, or down to microvolts was very good.