Dave -
One last question on your baluns and such
from my inquiry, item 5:
¡°5. Your observed results of Z CMC offered by each CMC choke ? In form Z=R +jX and related Reflection Coefficient Gamma Vector = rho Angle Gamma? Or dB.¡±
Do you have plots of Z, X and R. Vs frequency of your chokes that you might share with us?
I¡¯m interested in how much CMC impedance you think (or know) is being introduced by the chokes.
I note that many seminal descriptions of the balun issue begins with the colored charts of Steve Hunt, G3TXQ (sk), who opens with a description of the impedance s frequency of various materials.
He concludes with a link describing how he measured, and another to a spreadsheet that converts the measurements to Z, R and X.
A pretty complete description.
Some have been unable to recreate the results, and gave offered their own measurements, like Jeff Anderson K6JCA (google and ye shall find), Jim Brown K9YC, whose work we have discussed here, and others, including Owen Duffy VK1OD and Tom Rauch W8JI.
But I note that many ¡°internet experts¡± I have read begin their reports or designs or whatever by stating or thinking they ¡°have enough¡± or ¡°should be enough¡± common mode impedance without offering a single measurement, or just thinking the impedance they are worried about is abs Zcmc, and leave it at that.
The website of DJ0IP you describe does the same thing. Not a measurement beyond SWR. For an estimate of how much impedance? Fall back on Steve¡¯s coloring book. While it is a collection of interesting bits and pieces, the site is an aggregator of the works of others, but at least offers a spot for one-stop shopping. Adherence to the physics and science is not quite as strict as you maintain.
With regard to figure of merit, there is nothing wrong with looking hard at SWR. You will recall an article on searching too hard for the last bit of SWR could be harmful to one¡¯s health! I post an insightful link to Owen Duffy regarding an obsession with chasing phase, but the phase of what? Impedance phase or of that presented by reliance on S11 phase, as the nifty RigExpert analyzers present. And as many amateurs seem to confuse.
Again, thanks for your continued contributions to the field!
Looking forward to a description of how much CMC choking you have in the baluns installed when you get a minute.
73
Ed McCann
AG6CX
