Phasors and ATUs
The phasor is not the frightening cabinet of horrors that some engineers consider it to be. While it may seem daunting, a basic understanding of its operation will make maintenance of the antenna system much easier.
Measuring Modulation
The closer the correlation between the modulating signal and the instantaneous value of the modulated carrier wave the better the quality of the eventual reproduction of the audio signal.
Electronic feedback
Most of the radio transmitters in use today depend on feedback, negative or positive, for their successful operation.
Antenna currents and field strength
Sometimes we lose sight of the relationship between current in an antenna and the resulting field strength value.
Concerning combiners
Until the advent of FM, combiners were rarely required. After FM was introduced, the need for a method of feeding two or more FM frequencies into a single
The IBOC FM waveform
The IBOC system for FM as developed by Ibiquity is a fascinating engineering feat.
IBOC antennas
Despite the hiatus in nighttime operation for AM IBOC, antenna research is continuing in an effort to comply with the FCC's existing requirements of two antennas for FM IBOC, and develop a system using one antenna that will satisfy the FCC's requirements.
Staying neutral
Because of inductive and capacitive circuits, it is often easy for undesired and usually unwanted oscillations to be generated in an amplifier stage. Neutralization is important to keep these systems at maximum efficiency.
RF amplifier basics
A radio transmitter is a collection of stages. How these stages function determines the operational capability of each transmitter.
Fixing signal problems
When reception trouble is reported, it's not always easy to find the cause.
Environmental, ground system problems
As the FCC continues to delete mandatory measurements and checks from the Part 73 rules, some unintentional traps are opened for the unwary engineer.
Building a better radiator
As public rejection of tall towers has increased, radio engineers have been paying more and more attention to AM antenna design requirements in an effort to develop shorter AM antennas that are as efficient as their taller brethren.
Test your RF system
Modern equipment is stable and reliable, but some things should be checked on a regular basis.
DA maintenance
With the FCC's reduced logging requirements, there is no excuse for a directional array not to have adequately written maintenance logs.
Multitenant towers
The use of somebody else's tower can be attractive, but before rushing into a contract with an existing tower owner, consider all the problems that can occur.
Diplexing AM transmitters
When vertical real estate is at a premium, diplexing AM stations may offer an cost-efficient alternative.
Lightning protection
with proper engineering precautions, towers can survive intense lightning attacks.
Grounding and signal problems
Adequate grounding means different things to different engineers.
IBOC and combiners
Some transmitter manufacturers have already announced the availability of FM IBOC transmitting equipment, and offered actual equipment at the NAB show. FM IBOC requires considerably more equipment than the AM version, and it is more expensive.
Thoughts about IBOC
Many engineers anxiously awaited the release of the National Radio Systems Committee's AM IBOC Report, in hopes that the report would reveal good news about AM IBOC.
New tower standards
In the U.S., the joint TIA//EIA-222 standard oversees the design of broadcast and antenna supporting towers.
Tower maintenance
There are very few jobs in broadcasting where one can start at the top; but tower maintenance is the one where it is best to start at the top and work down.
Top loading, part 2 of 2
Part One described the events leading to the development of top loading of broadcast AM antennas. This part continues with details of the types of top loading and discusses the use of the FCC's Rules in planning a top-loaded antenna system.
Top loading, part 1 of 2
Engineers charged with the job of designing a new AM transmitter facility nearly always try to plan for the tallest tower possible. This is not just an ego trip; it's because the taller the AM radiator, the higher the field strength developed in the listening area with a given power.
Impedance matching
We have all been taught that the load impedance must match the generator impedance in the case of non-DC voltages in order to obtain the most efficient transfer of power. In DC work it seems that loads with an improper resistance fail to work because the supply voltage is too low, or else burn out because their resistance is too low for the applied voltage, and simple Ohm's law applies.
