Sunday, July 19, 2020

Rig control is back after lightning damage!

The radio used in my shack is an ICOM 7200 that uses a CT-17 interface for rig control. This interface and the serial port card in my PC are the weakest link when it comes to surviving lightning. Usually a nearby lightning strike takes out the RS232/TTL converter chip in the CT-17 interface. This is a 10 minute job to take the cover off of the box and pop the IC out of the socket and insert a new one. Sometimes the serial port card on the PC goes out but that has only happened twice.

So we had just finished Field Day and the storm hit the next day just before the 13 Colonies got started. I had made my first contact for the 13 Colonies and was making my second contact when I noticed my log was missing the mode and frequency information. I quickly changed the IC in the
CT-17 but that didn't fix it so I switched COM ports and that didn't fix it. After a few minutes of troubleshooting and expecting the worse, I determined that the 5 volt regulator on the board was bad. I did a quick web search and found out that part is discontinued. The specs showed it was nothing special so I was going to substitute a different part but I found old stock from an Ebay seller. I purchased 3 from Ebay but it took 2 weeks to get here from California.

The regulators arrived and that night I installed it and we had 5 volts again! LED on the CT-17 was nice and bright. When I plugged in the remote cable from the rig the LED got very dim. Rig control still didn't work. Well crap. So I grabbed my IC-703 QRP rig and hooked it up and I still had no rig control. This told me that the IC-7200 radio was probably ok. I tried the other COM port again with no luck. I measured the output of the new regulator and it was 2 volts. I removed the RS232/TTL IC and the voltage came back up to 5 volts.

Another new IC was installed and rig control was back! Not sure if one of my spare IC's was bad or the low voltage made it go bad but the final body count was 1 regulator and 2 IC's. 

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