At 10/20/2007 02:38, you wrote:
>Additional to this comment, if there's any passive or active IM mixes >at the site, cranking up the power on sites where there are any other >repeaters with the same offset (e.g. other hams) can create serious >headaches if there are also very strong user input signals present. > >More power from one repeater adding to a standard mix of... > >Your input >+/- Your output >= Negative/Positive offset >+/- Their output >= Their input > >(Flip the signs as needed.) If you think that's bad, how about a 2 meter repeater & a paging TX exactly 5 MHz above the 2 meter output? Every 440 system on the tower was affected even though the paging TX was allegedly just for backfill running only 25 watts. Those that duplexed on one antenna were just about unusable, while those with large separation between TX & RX antennas did better. One lucky guy with a RX antenna ~20 above the top of the tower was almost immune. We never could solve that one, as it would source from just about any metal-to-metal junction at the site: air conditioner housing seams, conduit joints, tower joints, etc. For a while we had to have the 2 meter repeater run upside down from the bandplan to prevent the mix from being generated on all the 440 inputs, but eventually the paging TX went away, & the site's been very clean ever since. Bob NO6B
