Scott: Here's a couple of comments and suggested possibilities to investigate in tracking down the source of your problems.
1. Check the turn-on time (not X-ray operation time) for the X-ray equipment. The operator may turn on the unit, take one exposure, change film and set up for a second exposure, take the second exposure and then shut down the unit. That might account for the one minute (or so) duration. 2. Check out any low-power, automatic, motor-driven vent controls in your air conditioning system that may (only occasionally) come on during the day. Noisy, brushed motors may be used for such operations. 3. Don't rule out local sources generating power line conducted emissions yet. When the interference appears, quickly switch to a current probe and sense the AC line cord noise/current. Note the levels during and after the interference. Your AC line filter internal to the spectrum analyser may preclude detection when you disconnect the signal input cable. If suspicious current differences are noted, resume your search internal to the company. 4. Check to see if there are any pump controls nearby for storm drainage flow control (or other flow control, such as irrigation). These units are periodically polled from a remote control site (or operate on timers), and transmit a status to the remote site via RF links. I have such a slave valve site approximately 150 feet from my home and experience periodic bursts of interference (for 60 to 70 seconds) on multilple TV channels. Good luck, Mike Conn Owner/Principal Consultant Mikon Consulting
