On Sun, 11 Oct 2009, MCH wrote: > BTW, he also wants to 'compromise' by offering to relocate the > repeater off the 52-54 MHz segment so they will not impact his RC > operations. Some compromise, huh?
Call a radio shop and get a quote for what it will cost to change the frequency of the repeater and realign the duplexers. If you're in an area where coordination entities charge, mention the charge, and note the amount of time that it would take to be cleared for another channel. Bonus if you can get the coordinator to tell you now what the next available channel is and it's proximity to his frequency of interest. > I think he has the impression that RC channels are 100 kHz wide (they > are standard AM) because the 6M RC channels are spaced at 100 kHz > (53.100, 53.200, 53.3500, 53.400, Etc). Beg, borrow, or steal a service monitor and find out. > I've told him they cannot be more than 10 kHz wide, if that, and that > the FC repeater would be only 16 kHz wide, and at 30 kHz away the two > can coexist without interference. Standard broadcast AM is 10KHz, and is wider than most other forms of AM (except CB, where they will do anything they want with the signal). > Oh, the repeater in question is at least 20 miles away from his flying site. Calculate the pathloss from the repeater to the flying site. Assuming a 100W transmitter, 1dB of cable losses and 5.16dBi (3dB) of antenna gain, at 20 miles there is -32.442dB of path loss. 100W = +50dBm, so there is an "apparent" signal of +17.558 dBm at the flying site. This corresponds to 56.99mW, or .05699W. You could probably push this number even lower by calculating the mW per centimeter. Even with a relatively non-selective front end, his radio should be able to be free of front-end overload from your repeater. -- Kris Kirby, KE4AHR Disinformation Analyst
