Assorted Bandpass Filters, 75 ohm impedance

These filters cover a combined frequency range from 5 to 550 MHz, in various steps and bandwidths. See the photographs for the response of each filter, plus several pictures showing the entire collection plus a small carrying bag. All filters have a 75 ohm impedance, however if combined with matching pads they could theoretically be used a 50 ohm Z circuit.

The frequency response of each filter was tested via the following method: I fed the output of a fairly-flat broadband noise source (Applied Instruments) through a 2 dB in-line pad, then through the bandpass filter under test, then through a second 2 dB pad, and then to the input of the spectrum analyzer. The inline pads are used to improve the ‘impedance match’ between all devices, since all filters present a poor Z impedance at their input/output. The in-line pads help to resolve this issue.

The analyzer trace is in ‘averaging mode’, showing an average of 25 traces to help flatten the average power level of the broadband noise source. A tracking generator would have yielded more precise results, however I did not have access to one at the time of testing. The depth of band rejection is actually around 5 dB better than that shown on each trace (loss from in-line pads), thus most filters demonstrate 55 dB to 60 dB rejection at the undesired frequencies.

Note the two vertical markers on each trace. The green marker indicates the lower band-stop frequency, and the blue marker shows the upper band-stop frequency. All frequencies are in MHz.

I prefer to sell these as a lot of 9 filters rather than selling each one separately, so please do not message me about that. Shipping cost is based on your location.

RF bandpass filter assortment, 75 ohm impedance

Specifications