HELP!! Why is 145.47 off the air?
Well, this certainly wasn’t what I was *planning* for my next blog enrty, but I’m going to have to write it anyway.
As you may have noticed, I have had to turn the 145.47 repeater off the air. Tuesday afternoon, it started passing this horrible squealing noise. I suspect the noise to be an “intermod hit” that involves a 5 megawatt (that’s 5,000,000 watts) TV transmitter immediately adjacent to the building that .47 is housed in. You can hear the video “sync buzz” when the repeater is enabled. We have had this noise on the repeater before, but never quite this bad. In fact, the last time we had this noise, I simply bypassed the receiver preamp and all was well again. I’m afraid that solution won’t work this time.
What am I going to do about this problem? As soon as I return from a little football trip this weekend, I will pay a visit to the repeater site. I will do some troubleshooting to try to determine where the “mixing” of signals is taking place. If it is in the repeater transmitter, I will try lowering the power, checking the transmitter with a spectrum analyzer, and trying to determine where the “mix” is occurring. I can install an isolator on the repeater transmitter to keep RF from getting back into the transmitter PA from the outside world. I hope this isn’t the case, as a good isolator is around $1000. If the mix is NOT occurring in the repeater transmitter itself, I’m afraid short of getting the offending station to cooperate, I will have to install a tone decoder on the repeater receiver. This means that you will need to encode a 100 Hz tone to access the repeater. I’m not a fan of tone squelch amateur repeaters, but it will keep the repeater on the air until the mix disappears.
The good news is that the transmitter that I suspect to be causing the problem will be off the air after the February 29, 2009 DTV conversion. That means that the transmitter in which the “mix” is occurring will be going away. Wouldn’t *that* be nice?
On another note, I visited the 146.625 site today and tightened the noisy squelch on the repeater receiver. .625 had a similar interference problem last year. I had to tone it up but its fine now. I tightened up the squelch adjustment, so the repeater didn’t stay on the air passing squelch noise after the user has unkeyed his transmitter.
Why not give .625 a try?
I will keep you posted as to the 145.47 repeater’s status. Thanks again for reading this!
P.S. I will be unable to attend the Ten-Tec hamfest this Saturday. There’s a little football game going on down in
73 de Tim WB4GBI
