70cms notch filter



I’ve been having a bit of both with what I think is local noise on a non rotator UHF set up. Lots of obs are plagued with noise and they are generally poor quality. So, looking for a recommendation to have a play with a filter. I’ll be swapping lots of things round to try and solve this and bring the GS out of testing but could do with something that doesn’t cost mega bucks (I am regulary wrong so it might be another factor but I’m banking on local noise

This obs is a good example

The alternative theory is that this particular RTL-SDR is deaf as a post, hence will swap out for another


Wow could be some other source of local interference, try moving it around. But something else to consider how is your R Pi connected to the RTL-SDR? is it direct or do you have a short USB cable in between? If so equip it with a ferrite bead if not already. I found that helped my setup some what. I also found a small dongle that allowed me to power the RTL-SDR from a separate source rather than direct from the R Pi. both of these seemed to help me out. My site still has a few “birdies”, none quite as loud as your example, but has improved with the above.


Good example isn’t it :wink:

I use a 3m USB cable for both the VHF and UHF stations connected to the RTL-SDR, exactly the same. So swapping these about is in the plan. I like the idea of locally powering the rtl-sdr as a better way than a long cable with beads on it.

If I try and locate the source with a handheld there really isn’t too much to point in any one direction. So I’m a bit at a loss really