Topband: Question: tower drop wire(s) use as a vertical element

[Herbert Schoenbohm]

----- Original Message ----- 
From: "Rick Hiller" <rhiller at sdicgm.com>
> Developing a 160 meter vertical design for a small, restricted space city
> lot.
> Situation:  35 foot Rohn tower with a fiberglass mast out the top that
gets
> it to 50 feet. (Supports my 40/80 meter delta loop)
> Can anyone, please, point me to any article(s) or archived topband threads
> that address:
   a single drop wire - versus - multiple drop wires configured as
> a cage around the tower.           -or-


Rick,

Ending up with a 50' vertical on 160 without top loading a single wire or
multiwire cage is not going to be very efficient as a radiator by itself on
160.
.
However depending how your 80 meter delta loop is configured the total
length is about 287' for 3.5 and very close to a 1/2 wave on 160. Whether
the Delta for 80 is bottom fed or corner fed you could easily convert it to
160 with either some relays or knife switches or even alligator clip across
the insulators.   Rather than voltage feed the openned 80 meter Delta, if it
were me I would look to put break points so the total wire would approach a
3/8 wave on 160 about 185'.  This means that the horizontal portion of the
Delta close to the ground could be openned up at the farthest point from the
coax feed.  The braid of the coax should also be then connect to earth
ground right there with as many radials you can put down. You may want to
model this but you should end up with an impedence of 60 ohms   and about
200 ohms of inductive reactance which should be easy to tune out with a
series capacitor. (Even the 200 pf door knobs can be used without an
elaborate tuning box.)

You may have a better solution already in your 80 meter delta loop with a
few minor modifications. At least the slant up portion should give you so
vertical component that should beuseful for DX contacts.

73

Herb Schoenbohm, KV4FZ