Broadcast AM Reject High Pass Filter (2.6 MHz HPF) by RTL-SDR Blog

I was overwhelmed using my 41’ random wire at 25’ height horizontally installed between two trees with a 9:1 unun and 37’ counterpoise for my Raddy RF919 with a local AM radio station near me. I connected this at the end of my rg58 and the beginning of my rg316 that connects to the rf919. I did a scan and all those spurious signals are gone! It was really bad in the 2300-4000khz area. I’m very pleased. I seem to be receiving more signals now across the 2300-30000khz. It works as intended and the high rating is worthy. Solid construction and small in size great quality and Good price for all it has solved. Will buy another for sure. For shortwave enthusiasts, it’s a must have if AM is drowning you out.

Seems to do its job fine, but it is not a panacea for suddenly getting clean 80m ham band signals for me like others have reported. I cannot tell a difference on that band with it in place or removed on any ham band, using a Airspy HF+ Discovery SDR and a magnetic loop antenna. So this is not a silver bullet, and may not solve your interference issues. But it does attenuate the AM band as it claims to do. May be most beneficial to proper third harmonics of AM frequencies. Also with it in place it does attenuate the 160m band as it says in the title (2.6MHz HPF, 160m band is 1.8-2.0MHz). Would be better if it had a sharper rolloff closer to the edge of the AM band like 1.4MHz so that 160m could still be used. But, it does what it says it does, and is high quality and inexpensive, so 5 stars.

I have a 5K AM station station close by that swamps my SDR. This little device took care of that. Knocked the signal way down and cutoff most of the other AM stations. Small, Compact, easy to install and seems to be well built. I'm happy with the results on my SDR.

After having used this for a couple years now, this does work. It does let some through at times, but I believe it is due to close proximity. However, if I don't use this as well as the FM bandstop, it makes SWL almost impossible at times. I'll put these on, and the interference I get stops.

RTL-SDR makes good products. This little filter keeps the pesky MW bands out of my Airspy HF+ receiver front end at lower HF frequencies. Without this filter on the lower HF bands, I needed to add 20 dB attenuation to prevent the receiver from overloading thus limiting sensitivity. With the filter I can run full gain. The added bonus is the very low through-line loss all the way to 500 MHz. As you can see on the attached plot the filter meets specs. MW is down by -40 dB, -3 dB is as specified at 2.6 MHz, -1 dB is at 4.36 MHz. Midband loss is less than 0.5 dB from 5 MHz all the way up to 500 MHz.

Using this filter on an antenna I call a "sloper", which in my case is run with Andrew Heliax at about 110' up on Rohn 45g, with ground tied to the tower at feed point, and the center conductor terminates to around 100' of stranded copper wire suspended at about a 45 degree angle from the tower. Yes it's primitive. Instantly the filter made a world of a difference on the MSI-SDR. Proof is in the waterfall showing the broadcast band with 75/80 meters picking right up. I was not expecting this, and I will be buying another. Can't wait to try it with RSPDX in HDR mode. Looking at my waterfall screen capture, the bottom half is the same system without the filter. The top half is the same system with filter and the included SMA M-M adapter in line. I'm quite amazed.

I have one of those ATS-25 receivers where the front end is not great. My local AM station comes in along with HF signals. This device clears up that problem completely.

This item works very well, so far as I can see in my short tests. I have a massive AM station a couple of miles to my north, at 50KW during the day, and it splattered all over the bands, with harmonics everywhere. As long as I connect this filter *directly* to my SDR (an SDRPlay2) with the included adapter, the station is just gone, and I can hear other signals (except in the filter's blocked range) quite nicely. If I connect it via a balun or feedline, the interference is back: I'll try various shielding strategies, but as long as the shield is there after the filter, all is well. Shipped promptly, arrived in good order (had one tiny screw on the case loose, easily fixed)

I purchased a genuine RTL-SDR dongle which worked very well right through the HF radio frequencies through VHF and up to UHF. Decent enough sensitivity but it was plagued with interference from very powerful AM broadcast transmitters which saw spurious signals appear in various parts of the radio spectrum. It was still usable but annoying. Except for the 11 metre CB bands and the 10 metre Ham band. These were completely swamped with broadcast breakthrough. So I purchased this high pass filter which blocks signals below 2 Mhz and passes signals above. This completely cured the problem and made the RTL-SDR dongle even better. Well worth adding to your SDR setup.