Dip your toes in the waters

 

This coming weekend is the CQ Worldwide CW DX contest. You don't have to be a contester to jump in this contest. There will be some great DX  to be had so one can add contacts to an award you are working towards.  If you are a QRP op you can see how far your 5 watts will get you. At one time I even ran QRPp power and was amazed at the distances I made. The exchange in this contest is easy peasy a signal report (always 599) and your CQ zone. (Found here). If you are working your way up the contest code ladder this is a great time to log in some practice time. So double-click on your contest icon and roll in a few hours over the weekend in the contest.

Front USB ports on your PC.

 

The finished product.

Once a year I take some time to open up my PC and give it a nice cleaning out. I am shocked at how much dust collects just after one year. I built the system and spent some money on it so I want to do my best to look after the upkeep. My computer is tucked off to the side of my desk on a shelf built for it. Taking it out is a chore and I have to make sure each USB cable goes back exactly where it was removed. If not when I start my virtual com port program I get an error message that certain com ports are not working. 

I have been doing some reading on RFI these past few months and along with that comes the subject of grounding. One topic that came up over and over again was the front USB ports that some PCs have. Mine has such ports and it has been mentioned that most of the time these ports are not grounded to the chassis of the PC. They in most cases are grounded to the motherboard via the control cable that makes its way out to the USB  front board. 

Sure enough, my PC was one that did not have a chassis ground for the front USB ports. It was easy to do and was a jumper wire from the USB board to the PC chassis. At the time I had no green wire and had to use red but I will know what it is for. While I had the PC  open I did check the onboard USB ports and I have 11 of them and they are chassis grounded.

What does RFI have to do with Pins.......

 

I have been doing some RFI investigating, which has sparked my interest because I have been having some RFI issues of my own.  In my travels, I have read of something called Pin 1 problem. I went to a few websites about this and had a glance here and there but never looked at it closely. This past week I did a bit more of a deep dive regarding the Pin 1 problem. The name came from Neil Muncy in 1994 he wrote a paper entitled Noise Susceptibility in Analog and Digital Signal Processing Systems. In it, he describes how he found the common  XLR connectors used in the audio industry pin 1 was always connected to the cable shield connection. The audio gear would connect equipment pin 1 to the equipment metal enclosure, over time Neil noticed that this practice stopped and pin 1 shield ground was being connected to the circuit board common trace and somewhere on the circuit board the common trace had a jumper wire to the chassis ground. This allowed the RFI  that was picked up on the shield of the audio cables to travel. As Jim  Brown K9YC puts it:

"If the shield goes to the shielding enclosure,  current stays outside the box. If the shield goes to the circuit board then the current gets inside the box!" 

In the ham radio world, we use computers, external sound cards, USB hubs and ham rigs. All these could have a Pin 1 problem that may be our thorn in the flesh. Now when I say  "pin 1" problem with our gear there may not be a pin 1 used for shield grounding like the XLR audio connector the issue is the shielding or ground pin on the connector does not go to the case ground but to the circuit ground and then to case ground. The label of  Pin 1 came from as said earlier the audio XLR connectors pin 1 with was always the shield connection pin. When dealing with radio gear it's not Pin 1 per say but the connector ground connection does it go to the chassis but to the circuit board to possibly cause issues. 

If you find your radio gear has a Pin 1 issue such as your headphone plug metal housing does not go directly to the chassis ground but to the circuit board most times you don't want to get the soldering iron out to fix it. If stray RF is let's say getting into your USB cable from your rig to PC for rig control and you find you are having issues. I would suggest you first look at the grounding a bonding of your gear, it is a quality USB cable as all are not made alike. Finally, try a quality ferrite on the USB cable if it is stray RF is going places it should not. I mention ground and bonding of your gear because if your gear has proper chassis grounding but you either do not have it grounded or it done incorrectly you could be compounding your RFI issue. 

I did look at my Icom 7610 shop repair manual and most if not all critical RF potential grounding is chassis grounding. On the other hand, in my personal PC, well many items are routed to the circuit board ground and then a jumper to the chassis ground. As  K9YC put it regarding my PC "current is getting inside the box". 
So the Pin 1 problem is something for us to be aware of and to consider when going after RFI. Now when I say RFI I am including both reception issues and equipment acting up. 

Below are some great reads regarding the Pin 1 problem. 

Pro-sound website 

K9YC 

N4XL

Time to bring out the black book

 

In the past, I have like others had issues with RFI. When RFI's ugly head pops up I find myself wondering what I have tried in the past. If you are like me you have a hard time remembering if you had tried something and if so what happened. I decided it was time to roll out the black book. I will use this book to record what I have done, the results, and the steps I want to take. Recently I felt I had my RFI  issue resolved but on Monday while taking part in the Medium speed CW  contest I had N1MM macros freezing. The encouraging thing is this issue happened in the past and was terrible, now it hardly happens and gives me the impression I am slowly solving it. I have a few more ideas to try and the black book will help map a path forward in the journey.