|
|
|
MINIMUM LPFM EQUIPMENT LPFM stations can get by with a bare minimum of broadcast equipment, but some items should never come from a "bargain basement." Here are the five most important items you'll need.
MORE INFORMATION FOR THE FIRST TIME BROADCASTER...Of course in addition to these items that get you "On The Air", you'll also need studio gear consisting of a good audio mixing console, one or more microphones, CD decks, perhaps a telephone hibryd or complete talk show telephone system, audio editing and production computer, automation computer and program, perhaps a cassette deck, studio monitor speakers and amplifier and headphones.Every LPFM station has an ERP (Effective Radiated Power) of 100 watts based upon 30 meters above average terrein. Depending upon the type of antenna used and the height of your transmitter site and the amount of signal lost in your length of coaxial cable, you'll need an FM transmitter that will operate somewhere between 10 watts and 250 watts.Let's start with the description of FM Antennas. Almost every commercially made FM transmitting antenna mounts on a two and a half inche to four and a half inch outside diameter pipe. The following two basic types of antennas are commonly used.1. The Dipole. This is a vertical polarized antenna with roughly a 1:1 ratio, which means 1 watt in, 1 watt out. If your station is operating in an area where you need to "reach out" to the horizon, this antenna may make sense. It is an excellent car reception transmitting antenna.2. A Circular Polarized Antenna. This uses both vertical and horizontal planes to send out your signal. A single antenna of this design requires a little more than twice the Transmitter Power as a dipole since it has a gain ratio of less than one half. This antenna does not reach the horizon as well, but instead concentrates its power on building penetration and close in stronger field strength.3. Full Wave Spaced Circular Polarized Antenna. If your tower has enough room you may choose to mount a Two Bay Antenna. This requires that you have about (8) eight feet of vertical mounting space. It requires half the TPO or Transmitter Power Output of a single bay circular. It also tends to send the signal out toward the horizon better than a single circular antenna. With multiple antenna bays it is important to remember that the "center of radiation" is smack dab in the middle of the array. This means if you are suppossed to build your antenna at 100', you will need to mount the top antenna roughly four feet above or 104' to have the radiation center at 100'.4. Half Wave Spaced Circular Polarized Antenna. As the name indicates this two bay antenna requires roughly half the spacing of a full wave array. Antenna Spacing for this might be around 5' and the result is that you once again will need to double power transmitter and the transmitting beam from the array will be even more narrow with little or no radiation above and below the antenna, but rather a tight signal heading off toward the horizon. Excellent for flat land distant transmission.
Your coaxial cable can eat up available transmitter power. There are a number of coaxial loss charts on the internet but suffice to say you could loose between 25 to 50 watts of power just sending your FM signal to your antenna. This is one reason that people will hire us to come in and build your station, so that all levels are set up properly and line loss is accounted for.Without good audio processing your station just will not sound loud or competative. Let's face it...with only 100 watts you're going to need all the advantages you can get. If you can afford a good digital processor I'll suggest the Inovonics Omega_FM. It allows complete creative control over your signal as it can be controlled fully by a laptop or PC. Listing at $5880.00 it may be on your Christmas list but not in the budget. The very best alternative is again from Inovonics. The model 718 also know as the DAVID III. This processor really is a "Giant Killer" since it seems to be everybit as loud as the much more expensive Omega_FM.The EAS system will consist of a couple of high quality radios that lock on frequency, and outside FM antenna and an EAS Encoder/Decoder unit with printer. The current FCC rules require LPFM's to only have a Decoder, but it looks like in the near future the Encoder will also be required, so we recommend getting the right one now. It's just a smart decision and cheaper in the long run. These units also need a program interrupt switcher if you plan to leave your station in unattended mode. Amber alerts or children abduction notices are also broadcast over the EAS system.Need more help, call today...1-888-830-8223.
|
|
Website Owned by Erickson Broadcast Sales
Corporation - PO Box 2575 - Albany, OR 97321
|
