QUANTUM LOOP ANTENNA
I have had the pleasure of using a Quantum Loop form Radio Plus+ Electronics for the last
two DX seasons. The more that I use the loop the more I can appreciate not only the
workmanship that went into the Quantum Loop, but how well it works as compared to my four
foot box loop. This loop may seem small at first, but as you use it you will find that good things
do come in small packages.
I will begin by describing the box loop I have. It is based on the design used by Don Moman
many years ago. Don managed to figure out how to almost eliminate metal in the form of bolts,
screws, and other such material in constructing a three foot box loop. By doing so he created a
loop with less materials that would skew the pattern generated by the loop. This loop is diamond
shaped with a diameter of four feet. There is a simple single pick up inside of the 9 windings
that go around the arms. A 365pf tunable capacitor salvaged from a dead radio is used to tune
the loop. No amplification is used on this passive model. This helps cut down on overload in my
urban listening area.
I have found that I can get excellent nulls with the loop, to the point where I can use the
adjacent frequencies of all of my locals. By the way here in Winnipeg all the AM stations but
one are on the South side of the city and must beam North at night. I too live on the South side
and can see CKRC 630's towers from my home. All stations run 10,000 or 50,000 watts just to
make it more interesting. The loop is fine if you have lots of room in your listening area. It can
rotate and swivel to effect the sharp nulls necessary at my location. However taking the loop any
place else to DX is a major effort. Betwe en its four foot wing span, mounting post of 3 feet and
a base filled with 50 pounds of sand this is not a portable loop by any stretch of the imagination.
This lack of portability and my love of DX'peditions lead to the purchase of the Quantum
Loop. As I said it is small compared to the beast described above. The QL(Quantum Loop)
stands about 9.5 inches tall, 7 inches deep and has a 8.5 inch head. Inside the loop head is ferrite
bar wound with heavy Litz wire and is balanced electrically to within a fraction of a microHenry.
For those of us not too technically minded that means you will get an even null with this unit
unlike other loops.
The loop is fed into a 40+dB two stage JFET/MOSFET amplifier. This amplifier unlike other
loops such as the Palomar loop is adjustable so you can tailor the amount of amplification to
your particular needs. There is a tuning knob to help peak the loop to the exact frequency via a
tuning capacitor. The power supply can be run off the supplied AC adapter or via an easy to
install 9 Volt battery. The battery installs on the back outside of the unit so you never have to
open up the QL to change batteries. The DC power is great for those of you who like me are out
on DX'peditions wherever possible. A throw of a switch allows you to go from AC to DC. This
little unit packs up easily and can go any place you can. You can customize the unit by ordering
it with PL-259, RCA, BNC or Alligator Clips to input to your radio. Mine came with a high
grade of coax and two well installed PL-259's.
As you see this is no regular unit. It is all finished in a black plastic loop head and back base
which contains the amplifier. All of the components are top of the line heavy duty materials. The
bearing surfaces are even coated with a special Teflon/Fluon compound for smooth tilting. For
those of you who may own or have seen other ferrite loops this is the best bar none. Even the AC
adapter was picked so it would not create AC hum that would kill the weak signals you are
trying for. One final touch is the Shortwave filtering that is installed. This will help insure that
RTTY and CW stay out of the BCB band. Using the QL with my ICOM ICR-70 I have never had
Shortwave bleed through.
OK so it looks nice on paper but will it work. YES! YES! YES! I must admit I was sceptical
at first being used to my four foot beast. Local DX'ER Wayne McRae bought a QL first so I
managed to see it in action before buying. He was using it with his three foot box loop and was
very pleased with it. The first thing he discovered was that it did not pick up as much of the
noise generated by the TV as did the old box loop. This was good news as my two teenagers love
their TV and the TV would drive the ICOM nuts when it was attached to the four foot box loop.
This alone combined with its portability sold me. My DX time is up and the kids still can watch
TV. I have found that the QL works as well as, better than and sometime not as good as the four
foot box loop.
The not as well as seems to come at sunset for unknown reasons. The QL is not as quiet around
sunset compared to the other loop. Wayne has the same experience with his QL and three foot
loop. But once it gets dark look out, this little guy goes to town. There has been almost nothing
that the big loop can pick up that the QL cannot get. They quite often run even and on occasion
when I have to increase the amplifier's gain, the QL will bring up enough signal to out match the
box loop.
The nulls on the QL are great. They are almost as deep as the four foot and deeper than the
three foot in many cases. You can really see it shine when you are on a crowded frequency and
you swivel and tilt the QL's loop head to obtain a great null. The loop is full coverage from about
520 to over 1850 kHz, so you will be able to use it on the new expanded band. In fact mine tunes
to about 1975 kHz so I can use it on the 160 Meter Amateur Band. You will be able to really tell
which way a signal is coming from with the deep nulls you create. Mind you materials around
your radio area can skew these nulls but that is not the fault of the QL.
Combined with the adjustable amplifier this ferrite loop has proven it can work any where,
including motel rooms. The QL really is easy to set up when you are away from home and can be
hooked up to your radio and have you DX'ing in five minutes or less. I have taken it over hill and
dale and it still preforms as well as it did the first day it arrived. By the way for those of you who
may have found other loops have to be far away from your digital readout receiver the QL can be
as little as two feet from my ICOM ICR-70 and not pick up any receiver generated noise. Just
one more good reason to own a Quantum Loop, for those of us who use it in close quarters. By
the way my radio room is in the basement of the house and the QL does not mind being there at
all. This little antenna will go anyplace.
I have managed to compare the Quantum Loop to a Palomar Loop. The QL walked away the
winner in no time. The nulls were better and the adjustable amplifier made it superior to the
Palomar model. In side by side tests with my ICOM ICR-70, the QL proved to be the better unit
in every situation and with every station. In a few cases of very poor signals the QL brought
them in while the Palomar was still giving me static in more ways the one. I know of another
DX'er here in Manitoba using his QL with a G E Superadio and he is also very pleased with its
performance. In fact he is now looking at buying a better radio so he can get even more DX out
of his Quantum Loop. This may be its only draw back HI!!!!
One more little add on for you Quantum Loop that will interest owners of radios with no
antenna jack is that Radio Plus+ sells a unit that you can use by putting it close to your radio and
attaching it to the Quantum Loop to couple the two units. This works just fine and at last pricing
was well below the unit from Palomar. So as you see the QL will work with ANY radio you have
no matter its age or bells and whistles.
As you see I am pleased with the Quantum Loop and feel it is the best ferrite loop around.
If you would like a small but powerful loop this is the unit for you. You can write to the
manufacturer in regards to pricing and more data on the QL at:
RADIO PLUS+ ELECTRONICS
3635 CHASTAIN WAY
PENSEACOLA FL 32504
USA
Radio Plus
The email is radioplus@bellsouth.net.
I am sure that you will be happy with this unit. Oh yes the price was a good on too. About
half the cost of the KIWA loop and less than a Palomar loop too. Tell them Shawn sent. You
won't get a discount but it sounded like a good way to end the article.
E-MAIL AMANDX