George demonstrates how to cut a quarter wave stub to notch out interference. Emile packs for 2023 Winter Field Day. Mike explores W0CHP PiStar Dashboard. Plus, mysterious solar powered antennas installations are popping up. How could this be cryptocurrency miners? www.amateurlogic.tv
This was my favorite method of getting rid of interference in commercial installations. I though it had been forgotten.
Interesting. So what are all the options for notching an offending signal? Filter cavities, tuned 1/4 wave stub, ....?
You have to find the correct place to put the stub in the feedline as well. I've seen plenty of stubs not do what they where supposed to do because they where located in the wrong position in the feedline from radio to antenna. Stub placement matters. --Shane WP2ASS / ex KD6VXI
Another trick is to have the coax slightly longer and put a small adjustable cap across the end and use that to notch out the offending signal.
out of curiosity, how would one go about doing this? Find an even spot in the feedline in accordance with the wavelength of the notched frequency, and place the stub at that location?
For those that are wondering about stubs and their placement..... https://www.google.com/search?q=k9yc+stubs The info written by Jim brown, K9YC will do a lot better job breaking it down than I will. --Shane WP2ASS / ex KD6VXI
I find cutting coax with a sharp chisel and block of wood gives a cleaner more accurate cut. I used a stub to stop two meters getting into the TV, worked a treat.
