Experimenting with the LNR Quad band antenna -
Working at squeezing another band or two out of this
antenna.    I can now get on 80 meters, 40, 20, 15 and
10 and maybe even 17 and 12 meters with this one
antenna.
hamelectronicsmagazine.com
earlandrews.com -- these are mirror sites

August 15 2015 -0-
appended Oct 19-2015
My backyard configuration
is not the best for center
fed antennas but it is a
good backyard for end fed
antennas.

The pictures left show the
LNR matchbox suspended
up the metal mast at about
the 37 foot level. Sloping
down is the 66 foot
element.

Not shown in the picture is
the tuning stub at the 33
foot mark ..halfway down
the wire.

Im not using the original
radiator wire supplied by
LNR Precision. I cut my own
wire and have been
experimenting with various
configurations.

The most recent
experiments are to add
another band of
frequencies to the quad
bander without upsetting
the good operation on the
design frequencies of
operation 40 meters, 20, 15
and 10.

The manual is available on
line at LNR Precison web
site.
I added one stub at 33 foot mark. I had
to take off a bit of wire insulation of the
nr 14 stranded wire I was using to add
the stub.

I took a bunch of swr measurements of
this modified antenna. First I added the
old Par EF 40-20-10 coil with the
original piece of tag end wire about 5 ft
long. That resonated the whole system
to close to 60 meter band.
Iam more interested in 80 meters than
60 so I added a longer tag end of
around 16 foot or so and trimmed it to
get resonance in the lower 80 cw
band.  
Here is the LNR precision
loading coil that I "borrowed"
from the LNR 40-20-10 25 watt
antenna.

The coil is capable of handling
100 watts. The reason the other
antenna is only rated at 25 watts
is the components in the
matchbox - especially the
capacitor.

With the original tag end of
about 5 feet this coil.. when
added to my 66 foot radiator
resonated the antenna in the 5.7
mhz region. With a bit of work it
could have resulted in a 60
meter antenna. I dont have 60
meters on any of my radios and
Im more interested in 80 meters
for qrp this winter.
So I added a chunk of wire to the
coil of about 18 feet or so. I didnt
actually measure it. It got the
antenna close to 80 meters. I
then trimmed off about 16 inches
and came up with the SWR
measurement that is good in the
80 meter cw band.
Pretty good low SWR at the low end of 80. I just acquired a TS440S
that has a built in antenna tuner and it should take care of any swr
higher up in the phone band.
I should have done this work earlier. Now I have an antenna that works
on 80, 40, 20, 15 and 10 all with one end fed wire antenna. It might
also work on 18 mhz. The swr is a bit high at that frequency (about 2.5
to 1) but it might do the job with the antenna tuner to help.
HERE ARE SOME OTHER SWR MEASUREMENTS I made on the
antenna.
Above 3.455 was the bottoming out of the swr before I did some
trimming at the end of the antenna. Nice thing about this end fed
antenna is the low end is only about 5 foot off the ground and
access is easy.
October 19 -2015 (update) **-- I have started
working on this antenna again. Winter is closing in
and I want an antenna for 160 meters and I want to
try a coil (maybe 140 uh) at the 66 foot mark in
order to get on 160.

What I will be doing (today and tommorrow) is
winding a coil (with taps) using a T200-2 toroid.
I will tap it in various places so I can tap it off for 80
meters then use the whole coil (140 uh) for 160
meters.

I will be posting the results (in the next few days) in
this article here that I am working on now.
18 mhz SWR is a bit high but I will be trying out the antenna on 18 mhz
with my newly acquired TS440S. The 440S has a built in antenna tuner
which should take care of these types of swr encounters.

Right pictured 21 mhz resonance is a broad dip. The SWR is pretty low
across the whole 21 mhz band.

I will be drawing a graph and adding it on to this article in a day or two.

Below pictured 24.903 mhz which is in the 12 meter band. Once again
just like 17 meters..the swr is a bit high but an antenna tuner can take
care of that.
Below pictured the 20 meter band. It has a good low swr as well. OF COURSE .. a dummy load also has a good low SWR as well. The
proof of the pudding will be when I go on the air and try and make contacts.
On the ten meter band. 28.515 is the lowest swr point.

Swr rises up to 2 to 1 at 28.046. I mostly operate around
28.060 the qrp frequency during contests.

Generally.. the antenna is quite good right now as it
stands. I could try adding some stubs or trimming the
existing stub at the 33 foot mark of the antenna or
perhaps I could add on a few inches to see if it might
help bring the swr on 10 at 28.060 down. ( I might try this
actually).

As it stands now.. the antenna wires stubs and
extensions are just "twisted on" wires. I havent soldered
anything yet.
What I did do is put tape over the joints to seal it and in a
day or two I will bring out the soldering gun.

Actually.. I am really pleased with the antenna as it stands
right now.

It just barely fits in my backyard. The 16 foot or so tag on
end after the loading coil is sort of doglegged into the
back hedge at the end of the property. It isnt entirely a
straight line antenna but it does get me on 80 meters.

Actually. The LNR MANUAL  says this antenna can be
made to work on any frequency between 40 and 10
meters. It does not mention 60 meters or 80 metres.
The manual for this and other of their antennas can be
found on their web site.

Good question?? CAN IT DO 160 METERS?? --- I may find
out very soon (noted: 19-OCT-2015) 160 meter season is
comming as is winter here in Northern Ontario. I will be
trying a hand made (homebrew coil) of about 140 UH to
see if I can replace the existing coil with a larger
inductance and perhaps get a 160 meter antenna


BELOW PICTURED: the loading coil I added at the 66 foot
mark of the antenna and the additonal (about) 15 foot
piece of wire that runs off on an angle into the back
hedge. This gives me 80 meter resonance. This is an LNR
precision coil that I "borrowed" from an LNR precision
40-20-10 end fed 25 watt antenna. I read that the coil can
take 100watts (which is what I run mostly-- though I do
QRP for QRP nets and contests).
73 thats it for now.. Earl VE3AB -- click here to go to my home page  http://www.earlandrews.com or
http://www.ham
electronicsmagazine.com (mirror sites).

I also sell radio and electronics parts at my "commercial web site" http://www.nettyelectronics.com (NETTY ELECTRONICS)

I ALSO HAVE AN EBAY STORE NOW - Just search up Netty Electronics on ebay. Got to make a few bucks somehow!!
October 19th/2015  additons to this article --- more SWR measurements taken and plans to modify this
antenna furthur to allow 160 and 80 mtrs with multiple tapped coil replacing the existing fixed coil.  
Above is the sketch for the "modified"LNR precision Quad Band antenna.

Below is the SWR curves I made today using data from my measurements with the MFJ antenna analyser.
The curve is pretty sharp. SWR at 3.593 is almost perfect 1.1 to 1. -- I could leave well enough alone right now BUT.. I want to do
some more experimenting and I want to try 160 with this antenna to see what happens. -- SO.. I am starting to build a tapped
inductor.  Using a T200-2 toroid and some enamelled wire ..I am going to measure an inductance out of 140 uh tapped at various
places. Then with an aligator clip..I can choose taps and try and get an antenna which is "selectable" for either 80 or 160 -- in
addition to the original design frequencies of 40, 20, 15 and 10.
This article is being written and added to -- noted :  19 Oct 2015.