RTL-SDR RF Filters

[@danedewaard8215]

I would also recommend these filters, especially the AM broadcast band filter! Thanks for alerting the SDR community!

[@TheSmokinApe]

Thanks Dan, I appreciate you checking out the video!

[@rafaelgcpp]

Hey Ape, I live around 3km of an broadcast antenna farm, where most FM stations retransmit. I have to use one of that filters AND a 130MHz high pass filter I designed... It is a great help for listening to 2m APRS!

[@TheSmokinApe]

I'm glad to hear you figured that out, interference can flat out ruin the fun. Thanks for checking out the video Rafael!

[@AdamSWL]

Excellent video! Nice to see those filters on a Spec-An working as advertised. Thanks for showing the results!

[@TheSmokinApe]

Glad you liked it, and thanks for checking out the video Adam.

[@tomstrum6259]

Great video Ape ! ....The RTL-SDR 88-108 Mhz Block filter Does work the way you tested it....Unfortunately, It has a very Small Effect when used connected to an Actual radio in Moderate to Very Strong Broadcast FM environment....When connected to my TinySA Ultra scanning 88--108 Mhz local FM Broadcast stations & the 12" Telescoping whip antenna Connected to the Filter's Left side Sma connector thru 3 ft length coax cable, All Strong Local FM stations Leak right thru the Unshielded Plastic enclosure & Are 10 Dbm Stronger than Without the filter connected as if the Unshielded filter is Functioning like a Big coax cable Leak !!!.....Reverse Connecting the Filter (Right side Input) the Rejection is around only 25 Dbm effective....Your's might be different but my Filter does this Repeatedly Inside my home !! .....Just Fyi.....

[@TheSmokinApe]

I’ll have to do some testing on that. I needed the AM high pass and bought the FM at the same time just incase. Thanks for checking out the video 👍

[@TimGray]

sadly the FM blocker blows out the first part of the aircraft band. wish they would make one that had a tighter notch.

[@TheSmokinApe]

Yeah, that kinda sucks

[@TheGmr140]

great video, these filters are great for sdr radios.

[@TheSmokinApe]

They sure are, thanks for checking out 👍

[@WayneHarris]

Doesn't the AM filter also attenuate the 160m ham band?

[@TheSmokinApe]

Yeah, If I recall correctly the 3dB rolloff was about 2.5Mhz

[@WayneHarris]

@@TheSmokinApe Thanks. Appreciate the video. Ordered my filters yesterday..

[@TheSmokinApe]

Good luck Wayne

[@TrevorSpencer]

I've been looking at getting my first SDR, and I had no idea this might be an issue. Thank you for letting me know how to fix a problem I didn't even know existed. I'm sure you saved me some headache!

[@viewatyourownrisk]

In using the RTL-SDR I've experienced the same issues that Ape was showing here. So it is legit what he demoed today.

[@TheSmokinApe]

Glad I could help!

[@wb7ond]

Great video, informative, and sure is a nice spectrum analyzer... I have the Siglent model just below the one you use. If one owns, the order of magnitude lesser expensive, NANOVNA they can perform the same measurments, albeit with somewhat lesser accuracy. Also if you have a noise source and the TinySA you can also characterize the filters, youtube videos abound. Also be aware that these filters do an excellent job of mitigating overload of the radio, active antennas may suffer overload of the LNA built into these antennas. Orientation of the active loop may help for some stations... Thanks for these informative videos, always great info...

[@TheSmokinApe]

Thanks for the comment wb7ond and for checking out the video. I have both the TinySA and NanoVNA which are both handy products and are great for learning. I try to show a variety of tools are ways folks can look at or solve problems.

[@Tump2010]

I need to pick some up for my SDR. I would like the AM one powerful enough to connect to my main rig

[@TheSmokinApe]

I was thinking about your situation when I made this, I was actually looking at a AM HPF for the 7300, I'll send you the link.

[@rawexploiterp6951]

okay. just ordered FM bandstop filter. that might help me with receiving HRPT on 1.7 GHz, since i could see FM broadcast crossreads there.. i am not using Nooelec Sawbird+ GOES.

[@TheSmokinApe]

Good luck with it RE, those FM stations can be a pain to deal with 👍

[@wrenchmonkey3920]

thinking about using the nanovna build out board to roll my own filter.

[@TheSmokinApe]

That’s awesome WM, let us know how it turns out 👍

[@Coreazcool]

Thank you, my 10 and 11 meter frequencies are buried with and overlay of the AM bands. I've ordered the filter. We'll see how it works. I'm just frustrated why these freqs overlay...harmonics...multi-band antenna??

[@TheSmokinApe]

It is likely overloaded from close by stations, hopefully the filters help 👍

[@wild-radio7373]

#TeamReplay for the win!♡♡♡ Thank you Professor Ape! :)

[@TheSmokinApe]

Thanks for checking it all Aname 👍

[@madmax2069]

I knew that i had to pick both of the filters up when I bought my RTL-SDR. I have a powerful FM station close to me at home, and an AM station across the street when I'm visiting my mother. I did try the SDR without the filters in line and as I thought it was pretty much unusable on any frequency other than MW and FM broadcast frequencies. It was causing shortwave broadcasts to duplicate themselves, picking up FM and MW stations on other frequencies, it was all kinds of bad. The filters stopped that. When I bought my Shortwave radio and an MLA-30 I had to put them in line with that setup as well. I have to use the FM filter on my UV-5R (I know I can't transmit when that's in line, but I can't transmit anyways being that I don't have a license to transmit) due to the FM station overloading the front end. That radio station makes it to where I can't even get the weather frequencies, and can even interfere with the radio receiving the local repeater. Would be nice if I could get a filter just for that one FM broadcast frequency, because that is the only station causing all the issue at home. That station can bleed into another station on the opposite side of the FM band, and this is seen on multiple car radios. On some days it can image itself on multiple frequencies on the FM band.

[@TheSmokinApe]

You might be able to build a filter, but that might be a giant hassle. Thanks for watching Max

[@sp9mx]

Thanks for your video. See what filters I made with the LNA system for RTL-SDR on HF bands. This may be interesting for you.

[@TheSmokinApe]

Thanks MX, I will check it out.

[@davidvaughn7752]

Hi. Great vid! I use the NESDR Smart with an active mini-whip antenna and the front end of SDR Sharp is easily overloaded with this setup. I was thinking about these bandpass filters that you demonstrate. The mini-whip is basically made for these types of dongle SDR's and yet they are very sensitive as well. It takes hardly anything to overload my dongle/computer systems receive with RFI. I have an AM station 1/4 miles away (123.000 kHz Korean station) which creates havoc as well. Do you think that the AM bandpass filter would help? Or am I just going to have to put up with a significant RFI problem? Guess there is only one way to find out and that is just to try it. The maker of the Active mini-whip gives advice that it is a good idea to have the antenna grounded directly. I live on the second floor of an apartment, so grounding is an issue. Anyhow, thanks again and your vids are always informative. 73.

[@TheSmokinApe]

Glad you liked the video David. I am sure it will help with AM interference and at 16$ it's not a bank breaker either. Thanks for the comment!

[@ToNzHoLtZ]

Do you DTF your jumper, looked like a compromise connector

[@TheSmokinApe]

I did not

[@ny1t]

Thanx. More useful information. By the way, some of us are trying to escape youtube and their unAmerican censorship. Please consider also posting on Rumble, Odysee, Bitchute and/or other sites.

[@TheSmokinApe]

Glad you liked the video! Thanks for the info on the other platforms.

[@HangryGiant]

I have a mfj 1046 passive preselector would this essentially be the same thing as these filters?

[@TheSmokinApe]

Sorry man, I am not familiar with that.

[@thebluegrassfarmer]

Question: Not sure if anything can be done... but I monitor our International Airport... which is about 18 miles north of my location. I can hear the tower just fine.. but when a plane (jet) flies within a few miles of my location and transmits... the SDR overloads. I've adjusted the gain and that does help... but will any filter help in this overload type situation ? Thanks for the help TBGF

[@mrtechie6810]

You need AGC - automatic gain control.

[@frequencywatchers]

I Hate When Im On 80 To 10 Meter bands Im getting So Many AM Stations, But I Don`t Want Them, But This Will Block Alll The Reception In Them Bands, RIght?

[@TheSmokinApe]

It will help for sure 👍

[@AndyAAzeroAM]

Can you place these in line with each other or will that create havoc?

[@TheSmokinApe]

You can hook them up that way. Each will induce some line loss which will be compounded.

[@JReed305]

Ape, would you have a recommendation for front end protection for these SDR's? It's a pain to have to disconnect my SDR when ever I want to transmit.

[@TheSmokinApe]

That is a tough one, I do not. I typically have my disconnected which isn't the must "fun"

[@JReed305]

@@TheSmokinApe Yeah, I have mine hooked to a LoG antenna and much prefer to use it for receive. I have a bypass on the tuner it is attached to, but the short bit of coax from the tuner to the SDR still acts like a bit of an antenna bringing in my TX RF at a level I don't like. I ordered a unit off of ebay so will have to see what it does.

[@TheSmokinApe]

@@JReed305 good luck with it 👍

[@JReed305]

@@TheSmokinApe thanks 😁

[@panoshountis1516]

The FM band filter spills over the top of the range at 108 MHx to 122+ MHz, so not a good idea to wire it in if you want to listen to the Airband.

[@TheSmokinApe]

Fair point Panos, thanks!

[@ErnestGWilsonII]

First! 73 W3GUY Also: I am of course subscribed with notifications turned on and thumbs up! Thanks for making these videos and sharing them with all of us!

[@TheSmokinApe]

Glad you liked the videos Ernest 👍

[@radioguy19510]

These filters will work with any SDR and most analog receivers with 50 Ohm inputs.

[@TheSmokinApe]

Yeah, they are pretty good. Thanks for checking it out Norbert 👍

[@stridermt2k]

Good stuff! 73 de N2NLQ

[@TheSmokinApe]

Hey Michael, thanks for checking it out!

[@brendanb1541]

Fyi your title reads SRD

[@TheSmokinApe]

D'oh!

[@resonancewaves9659]

Help! My neighbor is using this to cyberstalk me. How do I block this?