Topband: Vertical again

[Richard Karlquist]

> Anyway still one problem is not clear for me.
> If I will make 30m high vertical and I will add a "hat" on the top
> is it better to use "isolating trap" between the top and the hat in 
> the case of 80m?
> Such system is described in ON4UN book /with 27m high tower/.
> I'm afraid that horizontal wires of the hat will deform a radiating
> characteristic of antenna on 80m and it will produce more energy
> in higher angle ,if so is such a "isolating trap" a solution?
>                    SP5EWY

I used to have a vacuum relay at the 60 foot point on
my 90 foot vertical.  I would open it up for 80 meters.
Now what I do is just feed all 90 ft on 80 meters using
an L network to step up 50 ohms to about 1000 ohms.
I haven't done a direct A/B comparison of the two modes,
but the 90 foot configuration appears to get out extremely
well.  Recently I discovered that I was QRM'ing a local
round table 3000 miles away without knowing it.  I was
able to just barely copy some of the stronger stations in the
roundtable with a beverage.  Also, the 90 ft vertical
doesn't appear to have high angle lobes; because I still need
an NVIS antenna to work locals.

Rick N6RK