Receiving lots of noise

[jsouth]

New to GMRS.  Setup a home base station for my self and my mom. Same setup for both of us. Ed Fong GMRS antenna, MXT115 radios. She hears me with very little noise or static. I hear a ton of noise when she transmits, same on all channels. We are 6 miles apart, fairly heavy suburban area but not many tall buildings and nothing over 4 stories. I am 500 feet in elevation higher than she is. Both of our antennas are roof mounted. I'm using 65 feet of Belden 9913 and she has 30 feet of generic RG8x. I'm assuming that it's the 8x but before I replace it, would like some thoughts/advice. Thank you.

[Jones]

It would be helpful to know what kind of noise you are hearing.  Also, what kind of power levels are you running, and what type of radios?

 

This may well be a case of local noise at your location. You should check for noise generators like cell phone chargers, (especially those new wireless chargers), older light dimmers, older style LED bulbs, even fish tank air pumps can generate RF noise.  I my case, I recently found that a certain brand of electric blanket causes RF noise, even when turned off, so I just unplug it when I get up.

[berkinet]

...he has 30 feet of generic RG8x. I'm assuming that it's the 8x but before I replace it, would like some thoughts/advice. Thank you.

 

I would wait on replacing the RG8x. Unless the coax is running right alongside a local noise source, it is unlikely the source of the noise problem. It is far more likely, as Jones suggested, the source of the noise is on your end.  But, to get a better idea, can you, again as Jones suggested, describe the noise. It is like static, whining, steady pitch or varying pitch. etc. If you can record it and post it somewhere, that would be even better.

 

BTW, one other test. If you can hear  too?any other stations, do you hear noise when listening to them? Or, if you don't hear anyone else, just open the squelch all the way until you hear open static - is the noise still there

[jsouth]

Both of us are using Midland MXT115 radios set to high power (15 watts). To my knowledge, nothing nearby causing RF noise.  There's not a lot of GMRS being used where I live so I never get to hear any one other than my mom or kids playing on their walkies. Those never sound good. The noise I'm hearing on my end is similar to a white noise generator. Steady and not varying.

 

Before I saw your responses, I spent some time trying some things. I read about installing a drip loop and ferrite magnets just below the antenna connection. After I tried that, my noise went away. I'm not sure if those changes actually fixed something or just by taking it all apart and putting it back together, mistakenly found the problem? Definitely unsure as to what exactly resolved the issue but if you have any feedback on the changes I made and if they are likely to help, I'd be happy to receive the feedback. Thank you.

[marcspaz]

Sounds like you made a nice little RF trap.  I hope its at the right frequency or you can reduce your receive capability, even though the noise level is reduced.

[axorlov]

Ed Fong's antenna is a J-pole. J-poles will produce common mode current on your coax, this is inherent in their design. Depending on how do you mount your antenna (steel mast, wooden mast, no mast, metal roof, shindles, etc...) you may need a more or less efficient common mode current choke. Some people can get away without using any, some people may need very efficient choke (coax coupling with steel mast is probably the worst case). The loop and the ferrites below the antenna do their work to suppress the common mode current and the associated noise.

 

https://en.wikipedia.org/wiki/Common-mode_signal, https://www.murata.com/~/media/webrenewal/products/emc/emifil/knowhow/26to30.ashx and uncountable other sources.

[BoxCar]

I'm using a J-Pole also but I'm having no noise issues. The feedline needs either ferrite beads or a balun installed about a foot before the antenna connector. I'm using a coil of feedline for my balun. Have you done either of these? The feedline balun is a 3 inch diameter coil of coax (3 turns).

[jsouth]

I installed 3 ferrite beads just below the connection at the antenna and one large approx 15" diam drip loop below that. It's Belden 89913 (free cable) and extremely stiff so the 3" diameter balun is out of the question. It's mounted on an 8' peice of PVC that puts the antenna base about 6' above my roof line.

I'm very happy with the results but will now need to see if it is indeed affecting the receive capability. I've tested out as far as 12 miles before all this noise started. I'll try again and see what happens.