Positive Contact

• Main
• Personal Intro
• Safety Tips
• Primer Intro
  • Finding A Frequnecy
  • Location of studio
  • Drive By Radio
  • FM Transmitters
  • Amplifiers
  • Amp Construction
  • Loads and Power
  • Filters
  • Antennas
  • Connectors & Cable
  • Studio Set Up
  • Digital & Internet
  • Final Word
• Legal
• Parts/Credit/Pages
• Soldering
• Antenna designs
• Amp Designs
• Misc. Designs
• FCC and Radio
• Frequency Calculator

FINDING A FREQUENCY
Before you can proceed any further, you must determine if there are any available frequencies in your area. Due to frequency congestion in the large urban metroplexes such as Chicago, Boston, LA, NYC, etc., this may be a bit difficult. You will need several items to do a frequency search: a listing of the all the FM radio stations within a 50-70 mile radius of your area; and a digitally tuned radio. Go to the FCC database to create the listing of stations in your area. Given the fluid nature of web sites, this Web link may change. You can go to the FCC home page ( www.fcc.gov ) to find the FM station database if the following link does not work.
FCC Database - http://www.fcc.gov/mmb/asd/fmq.html
Channel separation is the biggest problem. FM broadcast frequencies are assigned a frequency channel 200 kilohertz wide. Good broadcasting practice requires that at least one channel of separation must exist on either side of the frequency you intend to use. In other words, if you have picked out 90.5 as a possible frequency, then 90.3 and 90.7 should be clear of any receivable signals. This is why a digital receiver is an important item for the frequency search.
Once you have a complete listing of all the FM radio stations, look for possible frequencies with the appropriate channel spacing. Depending on topography, distance and the output power of the other stations, certain “used” frequencies may in fact be open. The FCC database listing is very detailed. It will show the output power, antenna height, etc. Compile a list of the possible frequencies. Then, using a digital FM receiver with an external antenna, scan and check these frequencies. Do this from a number of locations and at varied times within the area you propose to cover. In most cases. weak, intermittent, or static-filled signals can be ignored and counted as either usable or providing the necessary channel separation. Hopefully, you will find at least one or two usable frequencies. If you live in a more rural area or some distance from a large urban area, finding a usable frequency should not be very difficult. 87.9 can be used as a frequency under two conditions. One, if there is not an existing station on 88.1, and, two, if there is not a TV Channel 6 being used in your area.
After compiling your list of possible frequencies, have your friends check them out on their receivers or radios as well. It is helpful to do this since a variety of different receivers will more accurately reflect the listening conditions in your area. After all of this, you should have a workable list of frequencies to use.