Re: [Repeater-Builder] Motorola Nucleus II 900 mhz

10 Aug 2004 00:31:45 -0000

It's very possible that the PA has gone spurious.  It's also possible that you are experiencing intermodulation.  Does the interference always occur when the paging company keys up, or only sometimes when they are keyed up?  My point is, does some other transmitter have to be on the air (or off the air) for this to happen?  Remember that the PA in another transmitter may be able to cause intermodulation when it is not keyed.

I worked in the paging industry for many years and got blamed for a lot of interference.  Almost all the  times, it was not my company.  You never said what frequency your repeater is on.

Something that has been happening lately is the combining of paging frequencies from several transmitters into a single transmitter.  The Nucleus 900Mhz transmitter is a multi channel device.  You can put many frequencies into it, both 929 and 931Mhz frequency ranges into the same transmitter and it will switch frequencies and timeshare the same transmitter.  Now comes the problem.  Many of the single frequency Nucleus transmitters had bandpass cavities to help eliminate some of the garbage that was on either side of the carrier.  When they multifrequency a Nucleus, they have to remove the narrow band pass filters and let it all go through to the antenna.  The good, the bad, and the ugly goes out the antenna.  Not a pretty thing on a spectrum analyzer.

Paging companies are combining these frequencies because paging traffic is slowing down.  If they combine the frequencies into one transmitter, they can eliminate the rent on the other transmitters and antennas, etc. and make it very cost effective.  Reprogramming or recrystalling the old customer pagers would just be too expensive and logistically impossible.

Joe

At 06:15 PM 8/9/2004, you wrote:
Does any one have any info on the possible problems with noisy
Motorola Nucleus II  900 mhz transmitters?  A paging company coo-
locatde at the site with my repeater has one that's driving me up
the wall. I have been working with them for 3 months now, to get it
fixed. They recently changed antennas to one located about 25 feet
away but there are spurs on my input frequency but, that did a lot
of good. NOT. I'm about ready to fax Riley H. at the FCC. I'm trying
to be a good neighbor but I've about had it
73
AC0Y

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