Bill, Can you please elaborate on the shield housing used? I have similar noise on my VHF ham repeater caused by the same Flashguard 3000 system. I was able to reduce the noise during night operation by reorientation of the antenna at the expense of a less than optimum radiation pattern. The cellular company that owns the tower doesn't seem to have any problems with the RFI from the strobe lamps, but then they are using panel antennas directed away from the tower and strobe lamps.
Thank you, Bill, WA8WG ----- Original Message ----- From: Bill Smith To: [email protected] Sent: Tuesday, April 28, 2009 4:33 PM Subject: RE: [Repeater-Builder] Computer noise in 2M Repeater I have experience with several 451 MHz systems getting hammered by noise from the strobe. These were Flashguard 3000 units. During the day when the strobe tubes triggered once it wasn't noticeable. At night when the tubes were retriggered multiple times to lengthen the on time of the flash, it dropped our RX sensitivity by over 30 dB. A spectrum analysis showed noticeable RF from below 50 MHz, peaking around UHF and dropping off around 900 MHz. In this unit, the tubes are about 6 inches long. We installed a shield housing over the entire head and 20 feet down the power cable along with installing toroids on the power feed inside the head. Bill KB1MGH ------------------------------------------------------------------------------ Now. the strobe problem you're describing sounds like a potential horrible electrical problem at the site. In my experience an FM rig shouldn't be greatly affected by a strobe. It also shouldn't be causing a problem/reaction with the WISP gear (it may be causing damage to it!) so I'd definitely find out what is going is going on with the strobe. Good luck! Jacob Suter
