Hi all,
Hoo boy, Windsor/Detroit like any large metropolitan area is the pits when it comes to RF pollution. If it were light you could see it from another galaxy, if you want a good idea what I'm talking about just look at a night satellite image and see how we glow in the dark.
Specifically, the problem is desensitization or "desense" which is yet another way front end overload shows up but because it's so drastic it takes a whopping bit of signal to do it. Since the receiver is blocked altogether this sounds like something VERY strong, VERY close.
Most often it shows up as intermodulation or "intermod" which is signals mixing together one atop the other with some showing up alone where they don't belong. That I have noticed with my 2M mobile while passing commercial towers making reception momentarily impossible.
Being a ham operating on VHF/UHF I have encountered desense but only when a powerful transmitter is operating VERY close to me. I would then suggest that the offending frequency or frequencies be located and blocked appropriately. An FCC database search is a good place to start, the listings give transmitter locations in latitude and longitude. Another way is to look for nearby towers, antennas and "all the usual suspects", then use a frequency counter to find what needs to be blocked before reaching the receiver. You probably will have to enlist the help of a local ham or your friendly neighborhood technician for this and a broad band preamp ahead of the counter wouldn't hurt. If it's strong enough to trigger a count it's more than enough to knock the slats out of a receiver.
One last thing, your local Amateur Radio club is a great place to look for help and if they can't provide it they know who can. What you're actually looking for is an "RFI comittee" that tracks down sources of interference. One way or another hams are a most helpful lot even if they have this tendancy to push you into getting a ham license. (;->)
