| General > General Technical Chat |
| Review: Hantek DDS 3X25. Anyone own one? |
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| Pentium100:
Has anyone added output protection to their 3x25? I blew up the output opamp again and while they are not expensive (not cheap either - ~4EUR), the local store does not have them so I have to order it and wait for the store to get it. At least I made the 3x25 do a 11.5-12.5MHz sweep (sine wave). |
| T4P:
You requested too much power ? I guess it's time for you to ... couple a high power opamp as a amplification device . |
| steve_w:
Have you considered using an attenuator to isolate the the output? |
| Pentium100:
--- Quote from: Dave.S on March 08, 2012, 10:39:08 am ---You requested too much power ? I guess it's time for you to ... couple a high power opamp as a amplification device . --- End quote --- No, connected the output to the screen grid of a tube instead of the control grid. --- Quote from: steve_w on March 08, 2012, 10:54:00 am ---Have you considered using an attenuator to isolate the the output? --- End quote --- I'll try, assuming with the new opamp the 3x25 will actually give 3V when I specify 3V (has some intermittent problem where it would have reduced output at frequencies >4MHz). I guess I should buy a couple of BNC sockets, resistors and a cable. Or just add the two resistors inside the unit. |
| Mechatrommer:
i wonder how did i miss posts on 9th march. anyway, followup from 7th march, update... i reflowed usb chips and the neighboorhood components including connection to fpga, the intermittent hanging seems to go away since that. so bad connection on usb chip is another high suspect. @Pentium100: what output opamp you use for replacement? because the original LMH6702 flatness wont reduced until somewhere 10MHz, the -3db BW is at 30-39MHz. i've (and rfloop iirc) made some report on the 3x25 flatness in earlier page if you havent noticed. if you really need protection, you can try out placing protection diodes at the output to the power rails, but beware you'll risk routing the damage to psu section. or you can use high end opamp such as TI THS3091/5 to act as frontend protection, buffer and magnitude magnifier to ±10Vpp output looking at hi-Z load. |
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