Sunday, 12 October 2014

Notes from the Shack - October 2014

Computer Problems and RFI

RFI is one of life's deep mysteries. As my station evolves it comes and goes in strange ways. I used to blow my garage GFCI any time I ran high power on 80m. That no longer happens. The Carbon monoxide detector starts beeping on 40m - the power required depends on the mode with CW being the most sensitive. 10 metres makes my subwoofer growl.

More recently, a new problem cropped up. I noticed during the CW WW RTTY DX contest that on 15m my USB Keyboard or USB mouse would go off line when running full power. To reset then, I could just unplug for a second or two and then plug it back it. 2 seconds is a long time during a RTTY contest but fortunately both weren't disconnected at the same time, so I could respond to a call with either.

The next day, while transmitting on 17m, the computer downstairs started throwing errors while I was copying some large files. A longer second transmission threw the disk drive off line completely and I had to restart the computer to get it working again. The next day I powered up my desktop system and got the blue screen of death. Hours of testing revealed that my SSD had failed completely. It's under warranty so the manufacturer will send me a blank one in return for the defective one. Whether RFI contributed to the demise of the SSD I'll never know - but so much for SSD reliability - I've gone back to hard drives, and added mirroring because I don't want to have that happen again.

Finally, a couple of days ago, while reinstalling software on the computer, I noticed a loose connection on my power supply. It turned out the U-shaped lug on the negative side of the supply to the transceiver was completed detached from the supply. Now one might think that this would have rendered the transceiver inoperable. However it seemed to be working perfectly normally! It is likely that the return path was made either through station grounding or the much thinner gauge power circuit to the antenna tuner.

Once the connection was fixed, I could transmit full power on 15 metres without upsetting the station computer at all. Good thing, because my opportunity test it was trying to reach W1AW/KH0 in the Mariana Islands on RTTY. I could barely copy him and needed all the power I had to get through.

One must learn from one's mistakes - and so I should be glad that I have so many opportunities to become more knowledgeable.

73,
Chris

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