[Elecraft] Antennas

[Ron D'Eau Claire]

Ah, but Sandy, it's so reminiscent of the old shipboard installations! I can
hang a neon or fluorescent lamp on the antenna where it exits the shack and
it'll blink as I pound the key, just like Sparks did, Hi! 

But, yes, "direct feed" antennas that come into the shack require care to
insulate and isolate the high RF voltages. And there are
frequency/power/distance-from-human limits to observe to meet the RF
exposure regulations. 

I use a big manual L-net tuner for my end fed wire. AFAIK, all Elecraft
tuners use L-networks. 

Ron AC7AC

-----Original Message-----

This particular "technique" using a half wave antenna as an "end fed" wire 
can be VERY dicey if you run high power, but as Ron says the efficiency 
rises as the ground losses fall.  (Percentage wise)   A way to get maximum 
use of a 100 watter or a QRP rig when your space available is small.

Somewhere is this thread of discussions the "balun" is mentioned, especially

the 4:1 one.  IF you are using a 4:1 "transformer" type balun (the ones 
commonly wound on toroid forms)  Losses MAY be high and also destructive to 
the balun if there is a large of amount of inductive or capacitive reactance

the "balun" is dealing with!  Do not assume the reactance is "low" unless 
you have measured it as such at the frequency of operation!  "Choke" type 
baluns usually escape this "destruction" (burning up, overheating, core 
shattering, etc.) more easily than the transformer types!

Don't forget one of the simplest networks there is, the "L" network, is also

sometimes the most efficient yet devised.  Most of the automatic type tuners

are based on a multielement switching "L" network.

73 to all,

Sandy W5TVW