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Niches to Fill
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by WX7G on October 24, 2009
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The ham radio manufacturers are leaving some niches unfilled. DX Engineering, MFJ, and others might consider these products:
160 meter vertical:
A plug-and-play top band antenna. A base loading kit for the popular 43' vertical is a start. A top loading kit is another; a higher performance way to get on top band that retains all band coverage.
Ladder Line Balun:
It it isn't often that placing the balun at the transmitter and not at the antenna is recommended for a coaxially fed dipole. So why is this the advice given for a ladder line fed dipole? Given ideal symmetry a feedline choke at the antenna would not benefit a ladder line fed dipole, but given a non-symmetrical installation or an off-center fed design a ladder line feedline choke might be beneficial.
A 1:1 choke advertised for use between the unbalanced output of a tuner and a ladder line might be a good seller. "Avoid the under-designed 1:4 voltage balun inside your tuner by using the X brand 1:1 tuner balun." I know such devices are made but they are not advertised as such.
A one-stop RFI store:
Ferrites at one store, an AC line filter at another, it's hit and miss. The AC line filters sold are mysterious black boxes. What is the attenuation? Common-mode, Differential-mode, the test set-up? The usual but often useless 50 ohm in and 50 ohm out test set-up? What about UL listing? Damping resistors? Unheard of. I design custom EMI filters and from what I see I would not use a ham EMI filter.
I would like to see the snap-on ferrites with useful impedance vs frequency data. A good tutorial at the supplier would be great.
How about 'trial' RFI kits? Perhaps a rental? Purchase or rent an RFI kit that includes a very large number of snap-on ferrites, AC, and DC filters. Send back what you don't use and receive credit toward another purchase.
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