[TowerTalk] TowerTalk] Single point ground

Roger Parsons ve3zi at yahoo.com
Wed Nov 4 13:49:17 PST 2009


I think the definition of 'single point' can be a little tighter than it may appear:

My remote station is at a former AM broadcast tower - so that is very well grounded indeed. I also have an APRS digi on the tower (antenna at 260' on a 325' tower). The coax comes down the tower and through a surge suppressor where it enters the hut. The AC feed is underground for about 500' and is grounded to the tower ground at the service panel though wide copper strap. There is about 10' of cable between the service panel and the outlets for the APRS digi and TNC power supplies. A month or two back there must have been a lightning strike on the tower - I found that the digi and TNC power supply transformers had been destroyed - the fuses had clearly blown very forcefully. The radio and TNC, as well as all of the remote station equipment, were totally unharmed. 

I can only assume that that 10' of power cable was too much and allowed a large potential between that and the antenna cable. Either that, or the power company found a way to put DC on the AC line!

73 Roger
VE3ZI




      


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