[RTTY] Need Help

[Joe Subich, W4TV]

 > My neighbor took a lightning strike on his garage roof last Friday
 > that blew a small hole in it. His garage roof is about 75 feet from
 > my house. I expect that caused something to fail in my computer. I
 > will do more looking there.

If you suspect a computer problem, it is even more important to measure
the voltage on pins 4 (DTR) and 7 (RTS) of the serial port with MMTTY
in the receive and transmit conditions.

Again, the LEDs inside the RB+ should give you some indication if the
serial port is providing the correct voltage (> +5V in transmit) by
lighting in transmit but if your serial port has been damaged the
input of the RB+ may also have been damaged at the same time.

The way these things generally happen ... You transceiver is connected
to the RF ground (shield of the antenna coax and ground rod) while the
computer is connected to the power system "safety ground" (third pin
on the power plug) and the two grounds *are not the same.*  When your
neighbor was struck by lightning, the potential at the two "ground"
points became different (because they are not normally bonded together)
which caused current to flow from the transceiver chassis through the
interface to the computer chassis and to the "safety ground" (or the
other way).  As the voltage on the chassis of one device becomes
greater than the power supply voltage, this difference in potential
can cause junctions (diode, transistor, etc.) in discrete devices or
integrated circuits to become reverse biased in excess of the
"breakdown" voltage and permanently damage components.  Interface
circuits (serial ports, USB ports, transistor controls, etc) that
bridge two pieces of equipment are particularly vulnerable to the
problems of differing ground potentials.

73,

    ... Joe, W4TV

On 8/25/2010 5:25 PM, Dick White wrote:
>
> I believe I have found the source of my problem of the computer not keying
> my radio through a RigBlaster Plus.
>
> My neighbor took a lightning strike on his garage roof last Friday that blew
> a small hole in it. His garage roof is about 75 feet from my house. I expect
> that caused something to fail in my computer. I will do more looking there.
> Thanks to all who replied to my first post. There were 2 other close
> strikes.
>
> 73  Dick KS0M
>
> Richard C. "Dick" White
> Fulton, MO. 65251  U.S.A.
> whiter26 at sbcglobal.net
>
> Live simply. Love generously. Care deeply.
> Speak kindly. Leave the rest to GOD.
>
> Amateur Radio Station - KS0M
>
> _______________________________________________
> RTTY mailing list
> RTTY at contesting.com
> http://lists.contesting.com/mailman/listinfo/rtty
>