May 26, 2026 – “Frequency Coordination”
Tonight, we are going to talk about Frequency Coordination.
Frequency Coordination is a process where Frequencies are selected for
various repeater groups so that they don't interfere with each other.
The Utah VHF Society was founded in 1968 on the premise of providing
Frequency Coordination for Amateur Radio Repeaters in the State of
Utah. There were only a few repeaters at that time but it became an
issue when two different groups wanted to use the same repeater
frequencies at nearby locations. This obviously was not going to work!
The FCC rules defines the Frequency Coordinator in 97.201(c).
Section 97.203(a) states that the licensee of a repeater or auxiliary
station must use a frequency coordinator to select frequencies.
Section 97.205© clarifies that if an interference problem arises
between two repeaters, the licensee of the uncoordinated repeater bears
the primary responsibility for resolving it, highlighting the
regulatory weight given to the coordination process.
Back in 1968, there were two repeaters that tried to use the same
channel in nearby areas. All of the radio equipment at this time were
surplused crystal controlled Motorola, GE and RCA radios. They only had
one or two channels available. One needed to purchase two crystals to
make a mobile or handheld radio work for one repeater channel. The
second channel needed another two crystals for that channel. This could
get expensive adding more channels.
Soon after this the amateur manufactures started making 2 Mtr
crystal-controlled radios and many of them only had 6 channels. Wow, 6
channels! This was soon not enough and more and more channels were
added to these crystal radios. I remember buying an Icom IC22A which
had 22 channels all crystal controlled. Wow, That seemed like it would
be impossible to fill up plus all the expense! It actually wasn't
enough channels!
Prior to around 1974 repeaters in the 2m band were all located between
146 and 148 Mhz with gaps for simplex operation. Thus, the upper part
of the VHF band started filling up quickly.
We needed to separate these repeaters by both geography and by
frequency to make this work because most of the older equipment used
Wide Band 30 KHz bandwidth not like today.
Soon after repeater equipment manufactures started using narrower
filters in their receivers so that one could use 20 KHz spacing between
repeater channels. Utah standardized using this 20 KHz repeater spacing
because this would enable repeaters to be placed closer together and
actually give more repeaters in any given area because of our close
Wasatch Front population area. Some areas of the country chose a
narrower spacing of 15 KHz which required repeater spacing to increase
many miles apart to allow this narrower spacing to work with causing
interference.
Two-meter radios started using frequency synthesizers in the mid to
late 1970s which did away with crystallized channels and is the norm
today. That is when the 145 Mhz Sub Band of repeaters were added. Utah
chose the odd frequency numbers so that a Utah ham would know if you
said to change to the 49 Repeater that this means go to the 145.490
repeater. The 12 repeater means to go to the 147.120 repeater.
Over time more and more repeaters were added. Every group wanted their own repeater. Some of them wanted several!
Repeater Frequency Coordination’s increased until now where all
of the Two-meter band and most of the 440 MHz band are full along the
Wasatch Front. In other words, every possible repeater channel is
coordinated to some one or to some group on both 2 Mtrs and 440 MHz.
There are several UHF repeater pairs available in the Wasatch Front if
you want to put up a digital repeater using a 12.5 KHz bandwidth. These
would be in the lower 445 MHz part of the band spaced every 12.5 KHz.
Utah has also played a part in making frequency assignments on Simplex
Frequencies. This is an ongoing coordinated effort to make sure that
neighboring groups or Counties would be able to use a set of simplex
frequencies in each of their geographical areas and to minimize
interference between them. These assignments are shown on our Web Page
under Simplex frequency useage.
So, if you want to put up a repeater then please contact the Frequency
Coordinator which is myself, John, K7JL, and my contact information is
available on our Utah VHF Society Web page under Frequency Coordination.
Well that is all for tonight so I will turn it back over to the Net control station. This is John, K7JL back to net control.