Living with EMP'S

[robfrick7]

Pete,

I have a flex 1500 that took an EMP hit on the USB port last year. I disconnected
the antenna, but did not disconnect the flex from the laptop, with all equipment turned
off. The EMP wiped out the internal USB/serial converter inside of my 1500.
I also did not have my plastic laptop grounded to the Flex. The ground wire was
recommended to me by Flex.

Later, I bought a used/damaged Tentec Jupiter that had an EMP hit at the rigs serial port.
That hit killed the 'max-232' serial interface, Uart, and flash memory i.c's. Got the rig going.

So now, when I shut down my shack, 1st disconnect all serial/USB cables from all printers,
radios, and other equipment that is connected to the 120vac wiring in the shack, 2nd
pull my antenna coax from the last RF device (like my tuner (also I have the
feed line out to antenna(s) connected to a lightning ground)).
Now the lightning ground is separated from the house (shack) wiring ground.

Hope this helps,

Bob, kb8kco, Elecrafter soon to be!!
 




-----Original Message-----
From: Pete Smith N4ZR <[hidden email]>
To: Elecraft List <[hidden email]>
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[Jim Brown-10]

On 5/24/2012 10:05 PM, [hidden email] wrote:
> I have a flex 1500 that took an EMP hit on the USB port last year.

All these lightning things on serial and USB ports sound like Pin One
problems to me.  They also sound like equipment powered from different
AC outlets, perhaps even with MOV surge suppressors.  Both are well
known causes of lightning damage, as well as problems with hum and buzz.

73, Jim K9YC
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[Joe Subich, W4TV-4]

On 5/25/2012 1:40 AM, Jim Brown wrote:
 > All these lightning things on serial and USB ports sound like Pin One
 > problems to me.  They also sound like equipment powered from different
 > AC outlets, perhaps even with MOV surge suppressors.

They generally are "different ground" issues.  The radio is typically
connected to the antenna system ground (even when antennas are pulled)
and the computer is connected to the power system "safety ground".  In
addition, many computers keep the USB power alive during "sleep" and
often even when turned "off".

A nearby lightning strike can result is differences of several volts
between the chassis (antenna/RF ground) and the power "safety" ground
which shows up across the USB power (increases or decreases it).  USB
power greater than 7 or 8 volts or negative can and will destroy the
USB UART and other USB powered components in most equipment.  Better
manufacturers are now adding surge suppressors to the USB power and
data lines in their devices but they are not 100% protection.

Proper grounding and bonding are essential.

73,

    ... Joe, W4TV


On 5/25/2012 1:40 AM, Jim Brown wrote:

> On 5/24/2012 10:05 PM, [hidden email] wrote:
>> I have a flex 1500 that took an EMP hit on the USB port last year.
>
> All these lightning things on serial and USB ports sound like Pin One
> problems to me.  They also sound like equipment powered from different
> AC outlets, perhaps even with MOV surge suppressors.  Both are well
> known causes of lightning damage, as well as problems with hum and buzz.
>
> 73, Jim K9YC
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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