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

[EB4APL]

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
> _______________________________________________
>