Ralph, Yes a tower can soak-up energy and bite you... most often this occurs in medium-wave. And it is a "RF-burn" rather than a shock. I sometime conduct RFR exposure studys for broadcast facilitys.. and occasionally we find things that are hot enough to burn you... but not often above 30 MHz unless you are in the near-field of multiple kilowatts. There have been some cases in the past where a rigger would climb through the aperature of a live antenna wearing an ANSI suit and report that it was smoking!!! That is why un-controlled exposure limit is 100µW/cm^2 for gen public. There have been some interesting FCC citations at Mt. Wilson in the recent past.. try googling "Mt. Wilson RF Exposure" and see what you get.. it can be a real eye-opener.
At first blush it sounds more like a ground fault in your station. Was the feedline completely un-hooked from the station? How often is the feedline grounded to the tower? Are there any AM broadcast facilitys in the immediate area? A hundred feet up, with a hundred feet back down the line is approaching a 1/4 wave at AM broadcast freqs... makes a nice loop antenna for some of them. Try disconnecting the feedline and check for any potential between station and feedline would be my first suggestion. Mike K5JMP -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] Behalf Of Ralph Mowery Sent: Saturday, August 20, 2005 1:07 PM To: [email protected] Subject: [Repeater-Builder] Induced RF on tower and antennas Has anyone ran into RF being induced in the antenna of a tower enough to cause a shock ? The setup is a tower 100 feet tall. On top is a Station master cut for the two meter band. There are a couple of smaller antennas on the tower. About 25 feet away is a 150 foot tower. On it are several paging antennas of various types. Around the 100 foot level is a 70 mhz antenna. Fellow went up the 100 foot tower to unhook the Station master and got a very big shock. This hapened twice to him. All the power was cut off with the main switch in the shack that goes to that tower at the time. There was no weather conditions at the time that should have induced anything such as lightning within 20 miles. ____________________________________________________ Start your day with Yahoo! - make it your home page http://www.yahoo.com/r/hs Yahoo! Groups Links Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
