442.275 Repeater to Change Frequencies

When the 147.225 repeater joined the SMLRS, a long time interference problem was solved.  John, W0PM, was able to positively confirm that the intermittent interference was being caused when the 442.275 repeater AND his 147.225 repeater were transmitting at the same time.  Before the repeaters were linked, the intermittent problem was impossible to track down.

What is happening is not a result of an improperly built repeater, or malfunctioning equipment.  It is simply the laws of physics at work!  This is proof that third-order intercept interference does exist.  Here is an excellent link that explains many sorts of interference to amateur repeaters, including 3rd order intercept - http://www.pericle.com/papers/M102_Jacobsmeyer%20Slides_V2.pdf

Basically, we have our 442.275 transmitter, interacting with the 2nd harmonic of the 147.225 (294.450).  So, when you subtract 294.450 from 442.275, you get 147.825, the input of the 147.225 repeater!  This will allow you to copy radio traffic from the 442.275 on the 147.225.

In order to fix the problem, one of us has to change frequencies.  Since 2-meter frequency pairs are not available for our area, we are changing the frequency of our UHF repeater to 442.425, PL 162.2 Hz.  We expect the change to happen sometime in the next couple of weeks.  Until the change is made, the 147.225 repeater will not be linked into the system for the Thursday night NARC net.

Since the 442.275 is the hub repeater for our Nixa link system, this will also require us to re-program the RF link radios at the 145.270 and 53.270 sites.  John has offered to help us re-program link radios at all the sites as well as the repeater.

When the repeater frequency is changed, you'll see it here first.