Gift to

c o u ra g i n g a n d wo r th
reporting. In my ham shack
1 now have a rem oteco
ntro l un it whic h will
select any given rad ial on
the roof. rem ove it from the
antenna circui t, co nve rt it
to a dip ole. and allow me to
use it as a recei ve antenna .
He re's a sum mary of how it
o pe rates:
• Shrprisinglv, I find I ca n
load the se lected radial/dipole
o n transmit as we ll.
On ly o ne radial/d ipole presents
an sw r cha nge fro m
the basic 1:1 of the vertica l.
and that one o nly prese nts
1.24:1 .
• The basic unit does solve
the receive pro blem that
has plagued me for years
now. I can pull any signa l
out of the noise/QRM by
"rotating" the syste m until I
hit the o ptimum an te nna.
• Nb rec eive pr eamplifi er
is necessary, even though
several radi al s are cut for
ot he r fr equencies.
• So far. I have not lost one
QSO! I can co py everyth
ing!
• Noise level is redu ced
co nside rably. For example.
if one exa m ines t he ra t io of
M ise levi" to overa ll signa l
stre ngth w hen co m paring
the old vertical with the
new system, t he resul t s are
shown in Table 1.
. It is possible to null
foreign broad cast QRM. In
all ca ses, I've been able to
iift th e de sired stat io n
above the foreign broadcast
Q RM level.
• In 40% of the cases, my
ow n signal report goes up
one to tw o 5-units w hen I
transmit over the rad ial/dipo
le. in co ntrast to the
ve rt ical. Thi s differ e nce
dimini shes with distance. of
Vertical Percent of New Q New Percent
Call a factor noi se fact or of noi se
WB8CHJ 0 4 60 % 0 5 20%
tZA3AVP 0 4 50% 0 5 15%
K2ZTL 03 70 % 05 20%
K3VK 02-3 60·75 % 05 25%
W9UPV 04-5 4().50 %· 05 10%
K9HWIID 0 1 98 % 0 5 20%
REGULAR COA K
"o.~
c:::J SIl.o\O£O E L E lol[ H TS
A RE ADD I TIO NS TO
EKIS TI NG
INSTALLATION
Table 1.
HY-GllI IN 14ll1VQ - W3
OFl OT HEFl VEIHICllI L
AN TENN A
, SHORT LE NGT HS
OF AlUM I NUM
ClOT Il E SLl NE CONN ECT
RllIOl.o\LS TO DUC T rcec
ENCLOSURE TER r.llNUS
Jl.bn'i";;:l~ R£ L A Y CIRCUI T fl Y 1'1 AL U"' ;N U'" DUCT r uar
B- WI FlE FlOTOR CA3l E
CONT ROL
'0'
course, as t he ve rtica l cont
in ues to exc el over OX
haul s.
• If I ca ll CQ and severa l
stations reply, I now find
myself eager and able to
select the weakest signa l
respo nde nt fo r the QSO .
I'm finding a whole new
world of DX and QRP people
ou t there who were
probably there all along
- bu t I sim ply co uld n' t
hear them.
Now, I don't wa nt to mi s­
lead a nyone into th inking
that th is system e liminates
all 40-met er evening-hour
diffi culties. It does not. It
does, however, solve more
pro ble ms in this area than
anyt hing else I've ever seen .
So f ar, everyone I' ve
spo ken with has req uested
(over the air) a detailed explanatio
n of the syste m and
how it work s. I've fo und
that th is is not the bestway
to di sseminat e t he information.
It takes too much time
and reaches to o few peopl
e . This a rt ic le wi ll.
ho pef ully, inform a large
eno ugh audience and spa rk
other experime nts in this
direction . Most co nve rsati
ons, o nce I've explained
the sys tem, usuall y e nd
with the other statio n saying.
" How simple. I wo nde r
w hy no on e has done it
before ?" I have the sa me
question myself !
Othe r Benefi ts
IN HA IIISi-lA CK
Asid e from performa nce,
Fig. 3. O verall view (not drawn to scale) o f the QRM Killer system, composed of the existing
rooftop verti cal, the adapter boxattac hed to the antenna, a new feedline and lengih of rotor
cable, and the co ntrol bo x at the ham shack . In operatio n, the rad ials/d ipoles are steered
remot el y from the shack. Relays in th e adapter unit on the roof select any given radial pair,
discon nect them fro m the overall antenna, and re-con figu re them into an act ive-dip ole
antenna.
t he re are sev era l o t he r
benef its to be derived from
this configuration:
1) No "new" antenna(s)
m ust be constructed .
2) The switching unit is
not ugly and , thus, no new
neighborhood eyesor e is
created .
3) It is incredibly easy to
co nst ruc t -
4) It can be expand ed
easily. so that add itional
radials/dipo les ca n be added
if desired .
5) It is quite inex pe nsive
to put toget her as all parts
are readily ava ila ble from
eithe r a junk box. hamfest
flea mar kets, ham parts
dealers, or yo ur local Radio
Sha c k o r O ls o n Rad io
outlet.
6) It will work almost as
we ll on other ban ds as on
40 meters.
I hon est ly feel yo u' ll enjo
y b ui ldi ng so me thi ng
that, unt il now. has not
been do ne and is not yet
co mmerc ia lly .a va ila b le .
This means you'll be able to
co nfigure the design for
you r ow n part icu lar requireme
nts and be ab le to
complete ly baffle others
who will be wo ndering how
you are suddenly able to do
so muc h better.
How It Work s ,
While this ma y ndt be the
most ef fective exa mple of
the principle. the unit I co n­
struc te d fu nctions q u ite
simply.
Each .radial on the vertica
l is d isconnec ted fro m
t he ante nna, and ail in sul a­
tor is in serted as close to
t he orig inal t ie point as
possible.
Next, a sho rt jum pe r wi re
is affixed to the radia l,
w hic h t he n is connected to
a relay at the antenna . The
rel ay , u n less activated,
gro unds the radi al back to
the ante nna . In this fa shion,
t he vert ic al performs as
usua l un less a rel ay is
t urned o n.
Two rad ial s. o ppos ite
each othe r, tie to a single
90 73 Magazine· October, 1980