Coordination Guidelines
by Dave Baughn, KX4I

     I am often asked about the criteria that are used to coordinate repeaters. The Repeater Council has developed and refined over the years a set of guidelines. On two meters, the required separations are as follows: 100 miles for co-channel and 5 kHz, 90 miles for 10 kHz, 50 miles for 15 kHz, and no spacing is required for 20 kHz or more. In the 144.5 to 145.5 band, all channels are 20 kHz. In the 146 to 148 band, coordination is based on either 15 or 20 kHz channels as the particular situation dictates. The 15 kHz channels start at 146.010 and repeat every 15 kHz, i.e., 146.010, 146.025, 146.040, 146.055, etc. The 20 kHz plan starts at 146.020 and recurs every 20 kHz, i.e., 146.020, 146.040, 146.060, and so on. If you now have a repeater that is on the 20 kHz plan and you think it might work better on the 15 kHz plan or vise-versa, contact the frequency coordinator and he will check it out for you.

     Per a 2003 A.R.C. vote, the spacing requirement for 440 MHz and higher, has been changed from 100 miles for co-channel to 75 miles. Since the channel spacing on UHF is a consistent 25 kHz, no other guideline is necessary. When considering 440MHz repeater coordination, please consider 100 mile pairs before choosing the 75 mile criteria. Also, 100 miles is also the basic criterion for six meters and 220 MHz.

     Other factors are also considered. In the case of mountain-top or tall tower repeaters, more than 100 miles may be required to alleviate interference. Occasionally two very local repeaters can exist with less than 100 miles spacing. These and other possible factors are left up to the discretion of the Frequency Coordinator. A detailed computer study of the terrain between two sites is often conducted to aid in coordination decisions. Unless it is obvious that no interference will occur, we usually require approval from any short-spaced co-channel repeater operators.

     It should now be obvious that it is very important for the Repeater Council to have an accurate location for your repeater. I have discovered a few cases where the coordinates provided for a repeater were off by 20 to 30 miles.

 Unless there is reason to believe otherwise, the Council accepts the parameters provided by the trustee as correct.

     Please feel free to contact me if you have any questions about the guidelines or your coordination. I will be glad to talk with you.