Module 7 Flashcards
What sorts of things can your signals interfere with
TV’s and computer monitors
Other radios
Phones
Touch lamps
Baby monitors, CCTV etc
What can RF do to TV signals
Pixelate the picture and cause breakup to sound
What can you do to minimise interference?
Move antenna further away from devices
Reduce power
Fit filters or ‘chokes’ to the antenna and/or ‘pickup’ cabling
Use filters on mains power supply leads
Address earth problems
How much interference do the different radio modes produce
FM - Less interference, “friendly modulation”
AM/SSB - More interference
Morse/CW - Key clicks can be a problem if on-to-off is not smooth
Data - Constant modulation, so less interference than AM
What are do’s and don’t’s for RF earth?
Don’t use mains earth
Don’t use radiators/water pipes
Do use a copper stake in the ground close to shack
Do use heavy gauge wire to connect
Best antennas for least interference
What type
How to connect to them
Horizontal dipole, balanced antenna
Connected through balun as coax cable is unbalanced
Where to setup your antenna
As far away from houses and other antennas as possible
As high as possible
Feed point far from house, RF ground can be close
What should you do regarding EMC and neighbours
What can happen if you cause interference, what can you do to help with this
Be nice, do some basic tests with them to see if you are causing interference
They can call Ofcom who may visit and test your equipment
Keep a log book, so you can check claims of interference
What should you do if you want to stick a radio antenna on a car
What is good safety advice
Get professional advice
You’re responsible for ensuring any radio is compatible with the electrical systems
Might need to inform your insurance
Test the radio while the car is stationary and with all electronic systems on
