We had a wandering spur passing through the Game and Fish statewide frequency at 151 MHz. The maintenance engineer had to put the spec-a on the IF section of the affected receiver [MastrII] to actually see it. One he saw it, he demodded the signal and it was a local paging outfit on 454 MHz. The paging company engineer turned off the transmitters one by one [simulcast system], until the interference went away. When they went out there, the PA tube had been recently replaced, and the technician hadn't properly neutralized it [Quintron?]. Seems to be kind of a lost art.
Another time, we had a 462 MHz pager that was EXACTLY half-way between our input and output on 460/465. Whenever we were on the air simultaneously, we got hit hard. It ended up being in his transmitter, and a dual-isolator on his end cured the problem. but he really disliked the loss of ERP. Thank heavens that company folded. WalterH --- In Repeater-Builder@yahoogroups.com, "Al Wolfe" <k...@...> wrote: > > Have seen this several times where a transmitter went spurious. The worst > have been Johnsons. It's often temperature related, at least the frequency > of the spur. A spectrum analyzer and a directional antenna are your best > tools. A portable scanner is also very handy. > > In one case we tracked down it was a small two watt telemetry transmitter, > not a pager, trashing a UHF repeater ten miles away when the temperature was > between 40 and 50 degrees. We found their spur was there any time their > transmitter was up but only on the repeater input at certain temperatures. > This particular transmitter was owned by a pipeline outfit. When we finally > were able to contact them their tech was quite knowledgeable and replaced > the offending transmitter. And they thanked us for bringing the problem to > their attention. > > With other entities sometimes we have not been so fortunate. Often when an > offending transmitter was identified we got denials of responsibility from > the owners but persistence and pressure from authorities have generally paid > off. > > Good luck, > Al, K9SI >
