I just bought a Hitachi VC-6025 oscilloscope from my Singapore trip for 85 SGD. It’s a good deal, since there is not a lot of second-hand electronics auctions on Ebay Australia, and the shipping costs from overseas or even interstate make it not very economical.

I was inspired by this blog post and decided to test the frequency response of the oscilloscope. I didn’t have any sort of frequency generator though, so I used a HP 8560A spectrum analyzer to generate the frequency.

25 MHz signal from spectrum analyzer

Not shown in the picture, there is a N type to SMA, SMA to BNC cable which connects to the scope (yes, this is very suboptimal but I don’t have many cables laying around - I still need to buy probes). The cable is connected to the tracking generator output of the SA.

As you can see on the screen, I’m operating the SA in zero-span mode. This also makes the tracking generator output to have a span of 0 Hz - effectively, it generates a pure signal.

By changing the center frequency I can select the output frequency of the TG. As shown in the image, the oscilloscope is triggering on the 25 MHz signal nicely.

200 MHz

At 200 MHz, the signal is heavily attenuated (as expected - the bandwidth of the Hitachi VC-6025 is 50 MHz in analog mode) and it is heavily unfocused, however it still triggers. Above 200 MHz it is so unfocused, it becomes unrecognizable.

Bonus image: why CRTs are just great to look at

CRTs