All good information.
Alpha used/uses a sectional RFC that is switched by a bandswitch wafer
contact. Expensive but it allows considerable leeway for out of ham band
use. I have seen others that use a LV switch wafer to control vacuum
relays but this was for commercial 5KW 2-30MHz continuous coverage.
The bottom line should be to build to your own requirements and get as
complicated as necessary. Overkill just complicates the layout and adds
For just the 9 HF ham bands, 1 RFC will suffice for most builders in the
I still feel that #28 wire is sufficient, it is used in the big
Ameritrons, MLA-2500, Amp Supply LK-800 and even the Alpha 77DX/SX.
The Ameritron measures 212 uh; I can provide winding info if desired.
73 Carl KM1H
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