AOR ABD128 vs RTL-SDR FM Band Stop VNA test

[veedub565]

I have both AOR ABD128 and RTL-SDR FM Bandstop filters. Out of interest I did a sweep on the VNA this week, and thought the results might be interesting to anyone considering buying one. I've got a MiniCircuits one on order and I'll sweep that one too when get it.

[veedub565]

I received the Mini-Circuits ZBSF-95-N+ filter today. I've run it on a different VNA this time and overlayed the RTL-SDR filter results

Mini-Circuits in Green
RTL-SDR in Blue

I'm a bit underwhelmed with the performance of the Mini-Circuits filter, especially considering it's cost over over the RTL-SDR filter. It's attenuation in the broadcast band isn't as good, although it does have less insertion loss and less attenuation at the start of the airband.

Unless you want to listen to the lower end of the airband I'd have to say the RTL-SDR filter is the best bet, certainly best bang per buck

[veedub565]

The Mini-Circuits on is well made though, I'll give it that. Not £100 worth better made, but still.

[radiolistener]

From my experiments, bandpass filter is much better. I have no benefit from RTLSDR FM reject filter - the result is the same as without the filter, but it attenuates a little VHF band.

In contrast when I use bandpass filter I see noticeable noise floor drop down and less spurs.