That Horrible Noise
The first place to address unwanted noise is in your own shack. This process begins when you design and set-up your radio shack. Consider non-RF noise as well; try to locate your shack away from the TV, living room or kids bedrooms.
Use the following guidelines as a starting point:
- Earth leads should be as short as possible
- Avoid second floor radio shacks if possible – but if you must, refer to 2nd floor grounding
- Ensure all equipment is earthed to a common point
- Avoid daisy chaining your earth leads
- Be aware of, and address, any RF feedback
- Minimise feedline radiation
- If the soil around your earth stake is dry, consider soaking it regularly
- Use ferrite noise suppressors on all power cables or data cables if you suspect noise radiation
- Stray RF – common mode current
- Unbalanced feedlines can be a source of noise. To prevent your feedline re-ratiating noise ensure that baluns are fitted at the antenna
Spend some time to read and understand the filters and tools that most modern radios provide to help in reducing noise.
- Digital Noise
- Noise blankers are good at reducing impulse noise like fluorescent lighting activation and electric fences.
- Band Pass Filters
- Narrow pass filters
- Notch filters
- Digital Noise
External filters may be fitted to antenna feedlines. Band Pass, Narrow Pass and Notch Filters can reduce the impact from known noise sources. Investigate external commercial digital noise filters and signal processors, for example:
MFJ (Mfj1026) noise canceller and bhi offer commercial options.
Consider wearing headphones.
If you think you have noise emanating from equipment in the shack, shut it down progressively until the noise is eliminated.
Alternatively, run your receiver off an independent 12v power source and turn on equipment progressively until you locate the offending appliance.