[Elecraft] K3: Added protection for RS-232 port

[Don Wilhelm]

Bud,

The "end of the cable" is not significant.  Lightning does not respect 
any particular "end of the cable".

The situation extends well beyond the RS-232 connection to the K3.  It 
includes everything in your hamshack.  The real answer is that in the 
event of a surge, everything in the shack should always be at the same 
potential - even if that potential is many kilovolts above normal ground 
potential (I do not exaggerate) - but achieving that requires providing 
some protective measures.

If you have done nothing in your hamshack installation to handle 
lightning surges. AND you in a high lightning incidence area, the best 
protection is to disconnect everything when not in use - do that until 
you have a good surge protection scheme installed..

Of course, that is really not always practical - so if you wish to 
protect your K3 correctly (along with all the other equipment in your 
hamshack), install some good lightning protection - single ground point 
entry point for ALL lines coming into the hamshack - NO exceptions - 
ethernet, telco, antennas, rotator, control lines, and yes even the AC 
mains entry to the hamshack should enter through a single panel 
employing MOV or other protection devices present at that panel for each 
and every line - this is the single most important point of lightning 
protection.  Look at all the equipment in your hamshack area, and 
consider everything within a 4 foot radius from each piece of equipment 
as something which should be within your "area of protection" - all 
lines connecting to those pieces of equipment should come through this 
"grounding window".  If you can touch any piece of equipment while at 
your operating position, it should be included in the protected 
equipment region.

That is a minimum - I would also recommend that you also have a 
perimeter ground wire around your house, and from each tower or mast 
(and vertical antenna), you have a good surge dissipating ground system 
installed consisting of at least 4 ground radials at least 30 feet 
long.  These ground wires should be #6 or larger wire and be connected 
to DRIVEN ground rods at intervals not exceeding 2 times the length of 
the ground rods.  The principle is to allow the surge to dissipate into 
"mother earth" as easily as possible.

Take a look at the information n the 3 part series on Lightning 
Protection that was pubilshed in QST in 2002?.  Go to the ARRL website 
and do a site serach on Lightning Protection.  The 3 part articles by 
Ron Block are my personal "bible" for lightning protections.

One important note - any grounding system (unless more than 150 feet 
from the house) must be connected to the house Electrical Utility ground 
wire - NEC requires it - ignore this fact at your own peril - failure to 
do that can destroy equipment and place you and your family in danger 
should a lightning surge occur (consider fire hazards).

73,
Don W3FPR

Bud Morin wrote:
> I hope this isn't true. Which end of the cable? For over a year I've 
> never disconnected it. I'm too old to reach around, under, or over the 
> shelves to try disconnecting and all that is involved in that.
>
> On 7/19/2010 6:08 AM, Pete Smith wrote:
>   
>>   Elecraft advised
>> me always to disconnect any cable from the RS-232 port on my K3 when not
>> in use, from which I inferred fragility.
>>     
>
> 73,
> Bud, K9ZT
>
>