[TowerTalk] End feeding a half-wave vetical

[K4SB]

dennis o'connor wrote:
> I doubt that a 9:1 transformer is going to do the job... The impedence
> at the end of the half wave is several thousands of ohms and is highly
> reactive - plus lthe reactance changes rapidly as the frequency is
> varied... All is not lost, however..

Not necessarily on the reactance. And a plain old parallel LC network
will match that antenna to 50 ohms exactly. Just tap up from the
bottom of the coil while adjusting the capacitor. ( I usually make
mine from RG8 ) Takes about 5 min to get perfect match.

There is a formula so old it's no longer published. It's called the
"LC Constant"
and is: LC=25550/F^2 That gives you the LC "constant", and from there,
you can dabble with both components, although I believe excessive
capacitance should be avoided.

One word of caution...If that antenna is a 1/2 wave for 80 or 160, be
doubly sure the ground end is grounded until the network is in.

Unless you want to get the hell shocked out of you, like some dummy
you know did with a balloon holding up a full 1/2 wave on 160.

):>
Ed