Three things to do... First, look at the "Pagers" license to see if he/she is running the proper power level, location and antenna. One across the street from me was running a 1/4Kw box into a 5.5 dB gain antenna, when the actual FCC License showed an allowed ERP of 23 watts, which as you can see is quite a difference.
Amazing what the change to the proper ERP will do... your first formal letter to the Pager Company you might imply a follow up letter to both the FCC and the Pager will follow should the "accidental excessive ERP power level" not be promptly corrected. Second, put a high quality 152 notch suck out filter on your 457 box... If you feel there is a chance something is getting externally multiplied up from the second harmonic, put an additional suck out notch filter network on the second harmonic. Ensure you have an isolator/circulator on your box. cheers, s. > Tony KT9AC <kt...@...> wrote: > > Hey everyone, > Working on a MSF5000 repeater with a 457 receiver getting overload from > a nearby 152 data transmitter (almost exact 3rd harmonic). The two > towers are about 10 miles apart and of course line-of-sight. > > I seem to recall that UHF duplexers only have a useful range of 300-600 > Mhz so that might explain why the 152 signal comes through so strong > (monitoring on the receive port of the Moto T4084 duplexer). The 457 > "harmonic" signal is also very splattery so I'm not entirely convinced > its just a mathematical problem, but I'll address that later... > > What would be the best course to eliminate this signal? I can't notch > out the harmonic since it falls almost exactly across our receiver, so > going after the 152 signal makes sense. Can I add a stub tuned 1/4 wave > with a T between the duplexer and receiver? Do I need something stronger > as a notch filer, or some sort of band-pass? > > Thanks in advance for any help. > > Tony >
