Summer reading: Common Mode Chokes
Now that it is September 1st and the return to school is right around the corner for many, it is time to start thinking about all that summer reading you've been putting off. Chuck Counselman (W1HIS) has a piece that you should add to your summer reading. The title of the work is Common Mode Chokes and you can find it here on the Yankee Clipper Contest Club web site.
If you have ever had RF in the shack, have higher than you'd like noise levels (especially on the lower bands), or any of a myriad of problems associated with common mode current running someplace it shouldn't, this is for you. In fact, even if you've never had these problems yet, trust me: you will. Read it now!
I've already had some problems along this area in my trips. For example, while in St. John for the ARRL DX contest I had a simple but very irritating problem: whenever I would transmit on a particular band my computer laptop's charger would stop charging the battery. I suspect is was something simple like the charger seeing a current on the wires leading to the power plug on the laptop and interpreting that as the battery is pushing back--it must be full. It is a stupid problem to have during a contest but I had it!
The reason I had a problem like that directly relates to the 100 Pound Dxpedition charter: do more with less and accept some compromises and tradeoffs. Everything on these trips is a compromise: I bring less equipment, run fewer radials, take smaller and more lightweight coax, and my installations are all extemporaneous and temporary. This kind of brazen tempting of fate is bound to generate some problems, including RF current running where you don't want it. This white paper discusses problems like this and does so very well.
I talked with Chuck for about an hour at Boxboro and while he calls this 42 page work an article I believe it more closely resembles the draft of a small book. In fact, I'm going to write Chuck today and make that very recommendation: don't cut it up to fit into QST; expand it, tighten it up, and make into a book!
This is an important work and has already been described by many as the seminal writing and thinking on this particular problem. Highly recommended.
If you have ever had RF in the shack, have higher than you'd like noise levels (especially on the lower bands), or any of a myriad of problems associated with common mode current running someplace it shouldn't, this is for you. In fact, even if you've never had these problems yet, trust me: you will. Read it now!
I've already had some problems along this area in my trips. For example, while in St. John for the ARRL DX contest I had a simple but very irritating problem: whenever I would transmit on a particular band my computer laptop's charger would stop charging the battery. I suspect is was something simple like the charger seeing a current on the wires leading to the power plug on the laptop and interpreting that as the battery is pushing back--it must be full. It is a stupid problem to have during a contest but I had it!
The reason I had a problem like that directly relates to the 100 Pound Dxpedition charter: do more with less and accept some compromises and tradeoffs. Everything on these trips is a compromise: I bring less equipment, run fewer radials, take smaller and more lightweight coax, and my installations are all extemporaneous and temporary. This kind of brazen tempting of fate is bound to generate some problems, including RF current running where you don't want it. This white paper discusses problems like this and does so very well.
I talked with Chuck for about an hour at Boxboro and while he calls this 42 page work an article I believe it more closely resembles the draft of a small book. In fact, I'm going to write Chuck today and make that very recommendation: don't cut it up to fit into QST; expand it, tighten it up, and make into a book!
This is an important work and has already been described by many as the seminal writing and thinking on this particular problem. Highly recommended.
posted by NE1RD's Blog at 9:53 AM
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