The RSGB Guide to EMC -- Tackle RF interference problems and understand the underlying causes.
AC Power Interference Handbook -- New insights into the causes, effects, locating and correction of power-line and electrical interference. 3rd Edition.
The ARRL RFI Book -- Second Edition. Practical Cures for Radio Frequency Interference.
General Rules for ARRL Contests on bands below 30 MHz (HF)
2.Entry Categories: The following categories are defined for ARRL contests on bands below 30 MHz. See the rules for each contest to determine which categories apply, and whether additional categories exist for that contest.
Single Operator: One person performs all transmitting, receiving, spotting, and logging functions as well as equipment and antenna adjustments.
Use of spotting assistance or nets (operating arrangements involving other individuals, DX-alerting nets, PacketCluster, etc.) is not permitted.
Single-Operator stations are allowed only one transmitted signal at any given time.
Single Operators may be divided into sub-categories based on power output:
QRP: 5-W PEP output or less.
Low Power: 150-W PEP output or less.
High Power: More than 150-W PEP output.
Single Operator Assisted: One person performs all transmitting, receiving, and logging functions as well as equipment and antenna adjustments.
Use of spotting assistance or nets (operating arrangements involving other individuals, DX-alerting nets, PacketCluster‚ etc.) not physically located at the station is permitted.
Single Operator Assisted stations are allowed only one transmitted signal at any given time, not including transmissions on a spotting net.
Multi Operator: More than one person performs transmitting, receiving and logging functions, etc. Multi Operator stations may be divided into sub-categories:
Multi Operator, Single Transmitter: Stations are allowed only one transmitted signal at any given time
In those contests that do not have Single Operator Assisted class, includes those single operators that use any form of spotting assistance such as from nets or PacketCluster.
Includes those that receive assistance with logging or relief operators, etc.
Limited to 6 band changes (maximum) in any clock hour.
The clock hour is from zero through 59 minutes.
Band changes are defined so that, for example, a change from 20 meters to 40 meters and then back to 20 meters constitutes two band changes.
Violation of the 6 band changes rule or improper logging will result in an entry reclassification to the Multi Operator Multi Transmitter class.
Multi Operator, Two Transmitter:
A maximum of two transmitted signals at any given time, on different bands.
Each transmitter is limited to 6 band changes (maximum) in any clock hour.
The clock hour is from zero through 59 minutes.
Band changes are defined so that, for example, a change from 20 meters to 40 meters and then back to 20 meters constitutes two band changes.
Violation of the 6 band changes rule or improper logging will result in an entry reclassification to the Multi Operator Multi Transmitter class.
Both transmitters may work any and all stations; the second transmitter is not limited to working new multipliers only.
Each of the two transmitters must keep a separate, chronological log for the entire contest period.
Multi Operator, Multi Transmitter:
A maximum of one transmitted signal per band at any given time.
Multi Operator, Multi Transmitter stations must keep a separate, chronological log for each band for the entire contest period.
