Expensive Mistake

McClellanville, SC
29 12.02 N 078 39.35 W

Whoops. I just committed a very expensive electrical mistake.   I have a graduate degree in electrical engineering, so I should have no excuse; but I did it anyhow.  Here's how.

Our primary source of entertainment on board is our Sirius satellite radio.  It's wonderful.  It works all the time, regardless of location.  That includes use offshore and in the Bahamas. Neither broadcast radio nor my Droid phone services offer that.   The sound is always perfect quality.  Interruptions are very rare. I use the direct connection wire to connect the Sirius radio to external speakers, or to the aux input of our AM/FM system.   However, when motoring, the engine noise makes the radio hard to hear.

I recently bought a 16 foot audio extension cord.  That lets me plug my ear buds into the Sirius so I can hear even when the engine is noisy.  With 16 feet of cord, I can walk around the cabin and go about my business.   Well, the other day out at sea I did it while posting a blog using the SSB radio.   It was the first time I ever did that wearing the ear buds.  Well, during the email post, the radio sound abruptly stopped.   I looked at it.  It was dark.  I tried to turn it on but it wouldn't.  I checked the power connection.  The fused connector was hot to the touch.  I tried wiring it directly, it caused a big spark and burned my finger.   The Sirius radio was fried and had become a dead short circuit.

What was my error?  I forgot about induced currents in the presence of powerful radio waves.  The SSB radio is a very powerful transmitter.   That 16 foot extension cord was a good antenna.  Dragging the cord near the SSB while transmitting must have induced such a powerful current in the extension cord that it fried the Sirius radio via the audio port.  Powerful indeed.  Expensive too.  It will cost me about $150 to replace the radio.  (I can't buy the least expensive Sirius/XM radio because those don't support the a-la-carte subscription with the $6.95 month fee.)

Live and learn.