From the March 2004 Idaho Observer:
Liberty Fix at Six
by Mike Heit
Having covered the Constitutional jurisdiction issue in this column last month, we now turn our attention to the basics of micro broadcasting station operation.
A person can put together a basic micro broadcasting station for less than $500 and it is the intent of this writer to pass on to the readers interested in such endeavor some knowledge about basic radio operation.
As you can see with the diagram below, the basic transmitter set up has a power supply, usually the home 120-volt system.
Most micro broadcasters are transmitting with an output power of 100 watts RF or less. Micro broadcasting transmitters start at one watt and go up to 100 watts, though there are a few out there operating at 200 or more watts.
For the purpose of this column I will use 100 watts RF as the maximum output power of an LPFM station. The costs of going over 100 watts of power out is very high. For example, I can build and sell a 100-watt LPFM station complete with antenna, coax and transmitter/power supply for $2,000 plus shipping, whereas a 220 watt FM transmitter alone starts at $3,000 and additional $2,000 to $3,000 must be invested for the coax and antenna. Then the monthly power bill makes the costs of operation prohibitive for most.
For a one-watt station that has an average range of one to two miles, a station can be put on the air for less than $500 -- including the basic input equipment such as a computer and microphone (see diagram).
To become an FCC commercial FM broadcaster at a power of say 5,000 watts would cost over $2,000,000 just to get on the air. This process takes up to several years to accomplish -- effectively keeping the common folks out of the operating loop.
Step by step walk thru the block diagram:
The Exciter Section
Referring to the block diagram let's begin with the portion of the station that actually converts the incoming signal to a radio frequency [RF] signal.
Technically this is called an Exciter. It is the job of the exciter to convert incoming audio frequency [AF] signals into radio frequency [RF]. The reason for this conversion of audio waves to RF is that the higher energy RF waves broadcast much further due to the higher energy levels.
To accomplish this, a signal is fed to the input of the exciter from a variety of sources. One of the most common is the microphone, also known as a transducer.
A transducer is a device that can use any source of signal that is to be converted from one form of energy to another, such as heat, light, sound and pressure, which are then converted, usually into an electrical form. In the case of the microphone, energy in the form of airwaves is converted into electrical [analog] signals, which are then sent into the exciter unit.
If signals from a CD player, phonograph or other device connected to the exciter are already electrical in nature, the exciter can work with them as a direct input.
Keep in mind that direct input signals must be properly monitored for their amplitude, which is the terminology for the level of the signal. If the level is to high, the sound you hear at the receiver will be distorted, if the amplitude is to low, you would need to turn up the volume to hear and the effective transmitting range will be reduced.
In a future article I will cover system components called compressor / limiters that can accomplish the task of keeping the direct input signals constant.
The Antenna Section
When the exciter receives signals they are converted into either an Amplitude Modulated [AM] or Frequency Modulated [FM] waveform. The primary difference in the two as far as the listening audience is concerned, is in the quality of signal reception. Up to the 1960s FM radio was not very common in the United States. AM was king and stereo was mostly unheard of in the era. The most sophisticated broadcast stations were all mono, and if they were really hip they may have had High Fidelity broadcast.
Some of you older readers out there may well remember Hi-Fi LP albums. In the mid 1960s stereo was developed as technology brought new forms of electronic components making stereo transmission and reception economically feasible.
When the input signal has been converted to an RF format, it is amplified and applied to the antenna system via a cable called a Coaxial Transmission Line. Coaxial cable is used to prevent unwanted signals from being impressed on the output line, or from radiating transmitted signals out of the line, and causing a severe loss of power or possible interference with the neighboring television and radio reception -- a situation that is certain to get the attention of the neighbors and be reported to the FCC.
A lightning arrestor bloc is inserted into the antenna grounding line to prevent a very nasty situation when the air is highly charged with electrical energy. Storms or extremely dry conditions and other factors can cause the air to be highly charged. Such charges can be conducted into the antenna line with a very disastrous outcome for the equipment or operator.
Properly grounded station equipment will prevent this from happening. You can see in the diagram that I have indicated a proper ground for any LPFM station set up is an 8-foot copper rod driven into the ground as close to the transmitter room as possible. For my station I have driven two 8-foot grounding rods and physically connect all equipment in the system to a 10 or 12 gauge [AWG] solid copper line that runs out the house to the rods which are connected together.
This not only provides a great margin of safety, it will also act as a path to ground for any stray noise in the LPFM equipment that could get into the transmitter and be broadcast. This noise is usually generated from phonograph equipment and other magnetic sources including the AC power supply of the home. It usually sounds like a hum in the background of the transmission.
Good operating procedures and planning of the transmitter room will prevent any possible noise from being transmitted out. Antennas are a science all of their own.
In future articles I will discuss the various types available and their relevant features as they apply to LPFM operations.
In my next article I will discuss the details of how to set up your own radio station, what you will need to get on the air and a comparison of different equipment available to you.
I'll also discuss the types of equipment you will need to actually transmit a signal and a begin dialog of developing a station-broadcasting format that would serve the needs and interests of your community.
Before someone decides to go on the air, a format needs to be decided upon; otherwise a rambling format will be the most common, and not too many folks will be willing to listen to your station.
National Association of Microbroadcasters
There is a new movement gaining momentum in our wonderful, yet embattled Republic. A new organization called the National Association of Micro Broadcasters has come on-line. If you are currently broadcasting on the air as a micro broadcaster or thinking about becoming a micro broadcaster, I urge you to visit the website and take a look around. The website can be found at www.microbroadcasting.org
If you have any questions or comments please feel free to contact me electronically with the contact info below or write to me in care of The Idaho Observer.
Till next time, fellow Patriots, may God richly bless you and keep you safe, may God bless our efforts to restore our Constitutional Republic.
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