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

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.

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.

For any ham or shortwave listener experimenting with Software Definable Radios (SDR), this little item is a must. Strong broadcast band signals can make a sensitive SDR essentially useless. This little filter significantly attenuates these broadcasts and enables the SDR to achieve its full dynamic range over the rest of the bands. As pointed out by the seller, this unit will attenuate the 160 meter ham band, but its -3dB cutoff of 2.6 MHz allows for good performance on 80 meters and up. Hard to beat the price!Added a network analyzer evaluation of the unit (see figure). Insertion loss ~ 0.15 dB, -3dB @ 2.7 MHz and -40dB @ 1.98 MHz. Ultimate out of band loss is on the order of 45 to 55 dB.

Perfect for the hobbyist listener, also beneficial for the HAM.Is it a great value? YESIs it a great filter? NOI bought this as a way to cheaply check for AM interference. I installed the filter and noticed an improvement. This justifies the cost of buying a professional filter for use with a high powered transceiver...which can easily cost 12 times more than this simple filter. For me, it was worth the investment.

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 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.

It does work, just not every time. It works more than it doesn't. I've found randomly I'll pick up a local broadcast station, maybe since it's so close that's why, but most days it blocks them all 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.