Cleaning up noisy signals, band stop filter, and interference

Skyd

Member
Joined
Jan 9, 2023
Messages
95
Location
Northern Grafton County, New Hampshire
Hey all - so I'm not new to this hobby by any stretch however I am starting to get more interested in diving deeper in. I have been a casual listener off and on for many years. That being said, I'm currently using a Radioshack PRO-106 with a Discone antenna mounted aprox. 20-25 feet off the ground. It is connected to my scanner via 50' of RG6 quad shield.

Now with some basics out of the way - on to my questions. I'm looking to "clean up" some noise both in general as well as in some signals. I'm sure I have interference I'm just not sure where to start with it.

My first concern is the FM radio band 88-108. I have 3 stations broadcasting from about .4 miles away at 250 watts (94.1, 98.5, 103.1) they sit about 300 feet above me so pretty good line of sight. I also have 3 more stations broadcasting within about 3 miles from me at a higher elevation 1300 feet above me and at a higher power - 580,450, & 390 watts. (91.9, 99.1, 106.3).

Lastly - I also have an AM station close by also about .4 miles squirting out 1000 watts on 1400Khz

Of course there's my electronics, wi-fi, neighbors, etc as well. I live in a house on a .25 acre lot in a neighborhood in a small town.

SOOOO, sorry this is getting longer than I intended but my questions are basically are these stations possibly causing me some interference and if so would it only be an issue on adjacent frequencies or could they be causing issues across the board? This is where I haven't much depth of knowledge.

Bonus questions - I also receive some strong signals 3-4 bars on my scanner, but there's much static over the modulation and hard to hear. Is there any way to clean that up? Is it possibly RFI on my end?

Lastly - I'm thinking of picking up a Nooelectric SDR dongle to play with, might this also be used to find out some problem frequencies where i'm picking up interference and those pesky spurious RF emissions.
 

N1EXA

FT8 Huntin Mudd Duck on the deep end of the pond !
Joined
Mar 3, 2022
Messages
219
Location
Acushnet Heights New Bedford MA
All kinds of traps on ebay for AM and FM Broadcast interference

I have the Noo Smart SDR with the Upconverter for HF band and Run HDSDR for Software - Works good for me



Pete N1EXA
 

kb5udf

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Premium Subscriber
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Apr 7, 2004
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801
Location
Louisiana
This is a tough RF/scanning environment. I would expect significant problems on civil aviation and military aviation bands, and potentially who knows where else from those FM transmitters. I’d start with a high quality FM trap (band reject) filter such as made by PAR, mini-circuits or Stirdsberg.
 

Skyd

Member
Joined
Jan 9, 2023
Messages
95
Location
Northern Grafton County, New Hampshire
Thanks for the speedy replies. My initial thought was I should just invest in a band stop filter for those frequencies. Can I stack the AM and FM filters without losing too much gain overall?

Forgot to mention there's also a UHF TV channel broadcasting nearby at 524-530mhz - It's NH Public TV, not sure the power.

I can pull in some surprisingly far signals considering the terrain here but lots of noise.
 

N1EXA

FT8 Huntin Mudd Duck on the deep end of the pond !
Joined
Mar 3, 2022
Messages
219
Location
Acushnet Heights New Bedford MA
I have to run an AM trap on my RTL SDR and Kenwood R5000 to remove the Local AM 1420 Station and an FM trap on a few
of my scanners to resolve the FM 98.1 getting into the aircraft band on my Uniden 785 and 15X.
You might get a little line loss doubling up the traps but if its get the job done your better off.
The RTL SDR is pretty open ended with no filtering so it gets overload pretty easy like local CBer's. or
If your on 5-6 Mhz the HF stations will fight each other but you can manually adjust the AGC gain and RF input with the software.
I find the RTL SDR to be pretty figity on antenna's and Impedance - just throwing a random 50 feet of wire out there does not cut it.

Pete N1EXA
 

N1EXA

FT8 Huntin Mudd Duck on the deep end of the pond !
Joined
Mar 3, 2022
Messages
219
Location
Acushnet Heights New Bedford MA
If you buy any SDR dont run it off the PC direct - Get it a good distance away and run a USB Cable - The PC and Power Pack generates enough
noise to mess it up - I mounted the SDR and Upconverter to a piece of Heat Sink to keep it cool and grounded. The up converter works
far better than running hf direct into the SDR Dongle.
Pete N1EXA
 

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Skyd

Member
Joined
Jan 9, 2023
Messages
95
Location
Northern Grafton County, New Hampshire
If you buy any SDR dont run it off the PC direct - Get it a good distance away and run a USB Cable - The PC and Power Pack generates enough
noise to mess it up - I mounted the SDR and Upconverter to a piece of Heat Sink to keep it cool and grounded. The up converter works
far better than running hf direct into the SDR Dongle.
Pete N1EXA

Ooooh, thanks for the tip, I like that setup. I plan to get one, but I think I'm going to spring for an FM Trap first. I have some heat sinks laying around though, and I like to frankenstien my own stuff so you've inspired me :)
 

N1EXA

FT8 Huntin Mudd Duck on the deep end of the pond !
Joined
Mar 3, 2022
Messages
219
Location
Acushnet Heights New Bedford MA
Ooooh, thanks for the tip, I like that setup. I plan to get one, but I think I'm going to spring for an FM Trap first. I have some heat sinks laying around though, and I like to frankenstien my own stuff so you've inspired me :)
This is A Noo Tapping of my Galaxy CB for a Pan adaptor- No Up converter - Remote cable and a heat sink - They get warm fast.

Pete N1EXA
 

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