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Buing tips about Used Function Generator

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Kiriakos-GR:
There is plenty of offers on ebay and pricing vary too.

I need an frequency generator up to 11 or 20Mhz, plus Duty cycle.

The questions are many:
1) is it worth getting a very old one from a major brand?
2) is it worth getting fresh model from unbranded channel?
3) is the 20Vpp a standard speaking about output?
4)does it worth getting a old programmable instead of an analogue? 
5) is there specialized people about function generators calibration or repairs?
6) does it worth trying to repair a broken one if you are not that expert on them ?   

robrenz:
If it is a DDS FG remember the max Hz specs are for a sine wave.  All the none sine waves will be significantly less Hz so you may need a higher spec to get the square wave Hz you need.

kaz911:

--- Quote from: Kiriakos-GR on December 14, 2011, 03:35:57 pm ---There is plenty of offers on ebay and pricing vary too.

I need an frequency generator up to 11 or 20Mhz, plus Duty cycle.

The questions are many:
1) is it worth getting a very old one from a major brand?
2) is it worth getting fresh model from unbranded channel?
3) is the 20Vpp a standard speaking about output?
4)does it worth getting a old programmable instead of an analogue? 
5) is there specialized people about function generators calibration or repairs?
6) does it worth trying to repair a broken one if you are not that expert on them ?   

--- End quote ---

Right now it seems like there are a lot of new FG's coming to the market at substantially lower prices.

The Frequency sets the price (more or less)

I'm waiting for the Rigol DG4000 series. It does not have a super sample memory (16k points). But price range is from $800 for 60MHz dual channel 14 bit FG to about $1600 for the 160MHz.  http://int.rigol.com/prodserv/DG4000/

If that does not work - i'll start searching again :-)

20Vpp is not standard. Some are 5v, some are 10v, some are 20v, some are 20v P2P OC but only 10V on circuit.

george graves:
Hope this isn't seen as a thread jack, but how would one go about testing a used FG?  Throw some different loads on it's output and see how it performs?

0xdeadbeef:
Regarding output voltage: 20vpp is indeed quite typical, but only in high impedance mode. In 50Ohm mode, most generators reach only 10vpp.

And about PWM mode: be aware that most generators are crippled regarding the duty cycle range. E.g. older model from Agilent support only 20% to 80% duty cycle - even for low frequencies. Some Rigols etc. only support 50% above a certain frequency range. That makes the PWM/DC feature kinda pointless for certain applications.

The next question would be if you need arbitrary mode and/or remote control via Visa/SCPI. Both can be very handy, but ARB mode is very limited on most affordable generators (e.g. 1MPoint would be state of the art, 16k would be acceptable, but everything below that is kinda useless). Also while e.g. Rigol generators support Visa/SCPI, the command set is somewhat crippled if you compare it to an Agilent 33521A (which is the best affordable arbitrary generator anyway).

Last but not least, the question is how much money you want to spend.

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