[time-nuts] Best location for a GPS antenna...?

Bob Camp lists at rtty.us
Thu Apr 12 23:54:11 UTC 2012


Hi

In the same area of "what I have seen". I used to live in a neighborhood where strikes were quite common. It was a rare summer month that there was not one or more hits in the neighborhood. Nobody's house burned down. They (I) did not loose every electronic device within 100' or 1000' of the strike. The thing *least* likely to be bothered turned out to be stuff with receivers in them (radios and the like). 

Bob

On Apr 12, 2012, at 6:58 PM, EB4APL wrote:

> Hi,
> 
> I have a personal reference:  In the Deep Space tracking facility where I used to work some 20 years ago it was very common to have minicomputers damaged by strikes in the antenna.  This antenna was located about 1000' from the control room and there were an elaborate grounding system both in the antenna (mainly intended to protect from lightning) and in the control room, but we got TTL chips damaged very often during thunderstorms.  The common believe was the high currents induced in the ground cabling caused  voltage spikes inside the computer cabinets enough to fry the chips.  I don't remember failures in the receivers, transmitters or other subsystems, but minicomputers were the usual targets, one or two chips each time.
> 
> Regards,
> Ignacio, EB4APL
> 
> 
> On 12/04/2012 23:21, Bob Camp wrote:
>> Hi
>> 
>> Do you have a reference for 100' distant strikes routinely destroying
>> receivers?
>> 
>> Bob
>> 
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Chris Albertson
>> Sent: Thursday, April 12, 2012 3:25 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] Best location for a GPS antenna...?
>> 
>> On Thu, Apr 12, 2012 at 11:56 AM, Randy D. Hunt
>> <randy_hunt960 at yahoo.com>wrote:
>> 
>>> On 4/12/2012 1:10 AM, Heinzmann, Stefan (ALC NetworX GmbH) wrote:
>>> 
>>>> What about mounting the antenna on the side of the metal pole, with the
>>>> top of the pole extending a foot or more above the antenna?
>>> 
>> Typically when a receiver or other radio is destroyed it was NOT because of
>> a direct strike.  A strike within maybe 100 feet is enough.  There is a
>> _huge_ EMP field around the strike.  The field will induce large currents
>> in any nearby conductors.   Even if the strike is to bare Earth many feet
>> from the antenna the potential of the earth is raised by say 1,000 volts so
>> now anything connected between ground the power has 1KV across it.
>> 
>> 
>> 
>> 
>> 
>> Chris Albertson
>> Redondo Beach, California
>> _______________________________________________
>> 
> 
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