[TenTec] humm

[Gary Hoffman]

Well I meant obviously that the bonding mostly IS Inadequate...sorry for the 
typo.


----- Original Message ----- 
From: "Gary Hoffman" <ghoffman at spacetech.com>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Wednesday, November 25, 2009 10:17 PM
Subject: Re: [TenTec] humm


> Resistance is indeed the evil.
>
> If one's bonding is inadequate - and it mostly is NOT !!! - then you are
> defeated.
>
> And there can be sneak circuits...and again you are defeated.
>
> And a direct hit....unless you have a ridiculously oversized system....you
> are defeated.
>
> BUT....for the common man....a really well designed home system buys you a
> lot of security against
> quite serious events, short of armaghedon (however you spell that ...grin)
>
> I have such a system, wayyy overdone, and I've survived some amazing 
> stuff.
> In fact, never had
> any damage at all...period.
>
> Lucky I guess !
>
> 73 de Gary
>
>
> ----- Original Message ----- 
> From: "Stuart Rohre" <rohre at arlut.utexas.edu>
> To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
> Sent: Wednesday, November 25, 2009 6:06 PM
> Subject: Re: [TenTec] humm
>
>
>> Actually Gary, what you say would be true in theory,  but for the mortal
>> character of wire resistance.  That is what allowed the surge to come
>> down the coax shield, (low R) and travel thru the coax connector, (low
>> R, to the circuit board traces to the power leads (higher R) and then
>> out the power negative (medium R) to the Astron negative terminal that
>> was tied to its case (higher R), which was also tied to the 3rd pin AC
>> ground wire (Highest R).
>>
>> Enough current was dissipated at each of the changes of wire/ conductor
>> gauge, to burn out components in the Astron; and in the rig, it
>> vaporized a section of circuit trace.
>>
>> Yes, in theory, you bond all grounds (outside the shack).  In practice,
>> if you have coax in parallel with a Chassis ground braid wire and AC
>> third pin wire, you may have a failure, if you also have a high
>> resistance crossing of AC and DC grounds inside the equipment.  The
>> change of gauges of the conductors was the resistance choke point for
>> the surge.
>>
>> This same surge took out the top of a power pole across a parking lot
>> from the shack.  Apparently a two stroke leader from the main lightning
>> event!  The pole was toothpicks down to the guy wire, which grounded out
>> the stroke, since it was larger and lower R than the copper pole ground
>> wire.
>>
>> AC grounds, antenna coaxes, and phone and internet ground connections
>> should all bond outside the building per NEC electrical code.  There
>> should be a metal entry panel with surge devices grounded to the
>> perimeter ground conductor placed to protect the whole building.  Even
>> this will not prevent some damage but mitigates most lightning events to
>> radio and TV stations.  Their towers are designed to take hits and come
>> right back on the air in most cases.  Their feedline gauge and element
>> diameters are typically much larger than ham grade antennas and towers
>> and feeds to enable this.
>>
>> -Stuart Rohre
>> K5KVH
>>
>>
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>
>
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