In article ,
VK3XL wrote:
Hi all, do you remember the old CD Stationmaster antenna? It was a end
fed 1/2 wave. I would like to make one and I believe there are plans
around to describe how its done, but so far I have not been able to
locate them on the net. Does anyone know of a link to such a page, or
even a magazine article etc. My work Library is quite good with regard
to old ham magasines etc.
The Stationmaster I'm familiar with is an end-fed collinear for VHF...
doesn't sound quite like what you're speaking of.
End-fed halfwave antennas for HF seem fairly simple to make, but also
seem to have a reputation for being a bit tricky to get working well.
The usual approach to matching is to use a tuned tank circuit, feeding
the tank either inductively or at a tap point partway up the coil.
http://www.aa5tb.com/efha.html shows one approach... this one uses an
inductive link to feed the tank.
The page at
http://www.smeter.net/feeding/tunehalf.php has a copy of
an article by Reg Edwards G4FGQ (SK) which shows the "tapped coil"
approach, and has a link to a copy of Reg's program to do the
necessary calculations.
--
Dave Platt AE6EO
Friends of Jade Warrior home page:
http://www.radagast.org/jade-warrior
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