On Wednesday August 25th 2004, Dan Williams, AMA District 2 Frequency Coordinator, visited the Cortland Aeromodeling Society flying site for the purpose of investigating some possible interference issue with Channel 12. I arrived at about 5PM and spent the evening scanning. I met with Joe Ludwig and several other members of the club. Upon arrival, I set up the Icom 7000 scanner set to scan every 10 KHz along the full 72 MHz band. Immediately I found a pager transmitter with voice and digital on 72.020 MHz, between channels 11 and 12. The signal strength was approximately S-3 using a whip antenna. The scanner was mounted on top of the roof of my Explorer. I also found a pager transmitter with significant strength on 72.900 MHz, between channels 55 and 56. This signal was about an S-2 on the strength meter.
Later on as the evening progressed, the signal strengths gained. The 72.010 MHz pager transmitter was about an S-4 and the 72.900 MHz pager transmitter was an S-3. There were other pager transmitters heard, but none caused the strength meter needle to move, but the squelch was opened. I don’t consider those others to be a significant issue.
A PERCON report from AMA (a service that checks the FCC database for inquiries to licensed services) reported only one pager transmitter in Cortland County, on 72.200 MHz. That wasn’t heard at all in the scans. The inquiries are done by specifying each county in question. The transmitter on 72.020 MHz is located in Tompkins County in Dryden. The distance is about 15 miles or so. There are 2 more transmitters in Ithaca, using 72.160 MHz and 72.320 MHz, but these were not heard in the scans. There is a pager transmitter in Lafayette on 72.040 MHz but this was not heard in the scans. My feeling is that terrain has a lot to do with what’s being heard and at what strength. The field is on the top of a hill that has a really good view of distant locations
My conclusion, based on the testing and license searches, is that the Cortland Aeromodeling Society refrain from using channels 11 and 12, and also channels 55 and 56. I’m including the 55 and 56 channels because the signal strength is not all that much less than the one that was affecting channel 12. A keen eye should be kept on further incidences, due to the fact that around Central New York, the list of pager transmitters seem to be growing. I would recommend a re-scan of the field be done every couple of years to see what new can be learned about clean channel availability. It is also recommended that any receivers that are not dual conversion not be used for any model that is above the size and weight of a typical park flyer. Most park flyer receivers are single conversion receivers and should not be used for larger models.
Dan Williams
AMA District 2 Frequency Coordinator
AMA Frequency Committee