Electronics > Beginners

Equipment to testing band pass filters?

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SoftwareSamurai:
Does anyone know of a way to accurately test a passive band pass filter that doesn't involve buying/renting expensive equipment such as the AT6011? Perhaps a DYI method involving reasonably-priced equipment?

I'm designing some passive band pass filters in the MHz range. I've got a Quakko SFG-2120 DDS and a Hantek DSO, and while I can manually scroll through the frequency range while watching the FFT on the o'scope, I'm finding it very difficult to accurately plot the filter's curve in order to verify the design. (Perhaps I'm not using them correctly?) I would love to get an AT6011, but alas I'm not flush with such disposable income at the moment. I've though about renting, but that seems like a bit of a hassle, especially since I may need to do testing several times a month in unpredictable intervals.

Any thoughts/recommendations anyone?

Thanks!

Kiriakos-GR:
How many Watts they will pass from it ?

Psi:
What kind of mhz range?

100-500mhz is going to be more tricky than 1-10mhz :)

SoftwareSamurai:
The BPFs I'm designing are for small signal applications. +5V, 100mA, 1-20 MHz range.

Psi:
It probably wouldn't be that hard to build something that can sweep from 1-20mhz and record the output amplitude.

Off the top of my head, something like a micro connected to a 1-20mhz freq generator IC.
Then use a precision rectifier to convert the BPF output to DC and measure the voltage with the micro ADC.
Could sweep the range quite slow and record lots of amplitude points.
Could even connect a graphical LCD to the micro and plot the graph.

I guess it depends how accurate you need the data.

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