[Elecraft] [K3] Be Careful in Lightning Season

[Joe Subich, W4TV]

Pete,

Are the chassis of your K3 and computer bonded together and are they
connected to the common lighting protection ground?

Are they both connected to the same AC circuit (same "safety ground")?

Have you removed (bypassed) L1 on the KIO3 RS232 board?

Is your RF ground system bonded to the power system safety ground at
the entrance panel?

Your symptoms are symptomatic of divergence between the chassis of
the K3 and computer with the result that the KIO3 sees reverse
"reverse" voltage.  RS-232 inputs are usually somewhat rugged since
they are required to accept +/- 25V in normal operation but enough
difference between chassis potential on two connected items will cause
that difference to appear on the connections (e.g. RS-232 input in
this case).

73,

    ... Joe, W4TV


On 6/18/2011 6:44 AM, Pete Smith wrote:
> About a year ago, when I first got my K3, U1 on the KIO3 board fried
> during a lightning storm, even though all my antennas and control cables
> were disconnected.  Apparently the damage was caused by EMP on the
> serial cable.  Anyway, $110 later I added a surge protector between the
> radio and the cable, and swapped the cable for a USB-to-serial adapter,
> thinking it might reduce the chance of future damage.  As suggested by
> Elecraft, I also started disconnecting from the RS-232 port when a
> lightning storm was expected.
>
> Well, last Wednesday night I was awakened by thunder and lightning, went
> back to sleep, and in the morning discovered that I had *not*
> disconnected the serial cable.  In fact, I'd also left the antenna on my
> QS1R - horrors!  The QS1R was OK, as it turned out, but the EMP fried
> both my USB-to-Serial adapter and the KIO3 - probably U1 again,
> according to Elecraft, which is sending me the IC so that I can attempt
> a repair myself.  Excellent support, as usual.
>
> It does seem, though, that the RS-232 port on the K3 is highly
> vulnerable - in some 15 years of using radios with serial ports, I had
> never before disconnected the serial cables, and never had any damage,
> even when my tower took a direct hit.  I have heard that Elecraft is
> working on a ruggedized version of the KIO3, and wonder - when might it
> be ready, and will it be a user-performable mod?
>