Hello and welcome to the 561st episode of Linux in the Ham Shack. In this episode, the hosts discuss the HamClock application. Topics include how to access, download and build the application. Then it's on to initial configuration, features, operational logic and more, including some hard to find and esoteric features that make HamClock an invaluable resource in the shack. Thanks for listening and have a great week.

73 de The LHS Crew

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

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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.

For the ARRL  Sweepstakes contest the exchange is the following... let's take my exchange for example:

112A VE9KK 89 NB

To break it down 112 is the serial number so the station I contacted is the 112 contact for me. 

The letter A  (called precedence) signifies low power (more than 5w and not more than 100w)  in a single op. Other letters are Q for QRP, U for single op unlimited power, M for multiop and S for school. 

Then you send your call VE9KK

89  (called Check or CK) is the year I was licenced 

NB (called Section or SEC)  is the province. 

Now think of all that info coming at you in some cases 32 to 34wpm. In this contest, it is very advisable to slow down to the station you are contacting speed. If not you will use up lots of time with repeats. 
Now once you send all this you may be asked to resend any one or combination of your exchange as it may have been missed. For example, you may hear PREC, CK? I would then resend A and then 89. 

Now the contest software from records most of the time fill in the stations CK, and SEC  BUT sometimes it's wrong and it has to be changed on the fly.
My effort was part-time as I could not spend any time on Saturday evening it was only late morning and part of the afternoon I was able to take part.
This is a great exercise for your CW skills!