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<p class=MsoNormal><b><font size=4 face="Times New Roman"><span
style='font-size:13.5pt;font-weight:bold'>O Link, caso não saiam as imagens :<o:p></o:p></span></font></b></p>
<p class=MsoNormal><b><font size=4 face="Times New Roman"><span
style='font-size:13.5pt;font-weight:bold'><a
href="http://www.n0lx.com/short4band.html">http://www.n0lx.com/short4band.html</a><o:p></o:p></span></font></b></p>
<p class=MsoNormal><b><font size=4 face="Times New Roman"><span
style='font-size:13.5pt;font-weight:bold'><o:p> </o:p></span></font></b></p>
<p class=MsoNormal><b><font size=4 face="Times New Roman"><span
style='font-size:13.5pt;font-weight:bold'>E Vale a pena ver o site todo deste
colega: <a href="http://www.n0lx.com/">http://www.n0lx.com/</a><o:p></o:p></span></font></b></p>
<p class=MsoNormal><b><font size=4 face="Times New Roman"><span
style='font-size:13.5pt;font-weight:bold'><o:p> </o:p></span></font></b></p>
<p class=MsoNormal><b><font size=4 face="Times New Roman"><span
style='font-size:13.5pt;font-weight:bold'><o:p> </o:p></span></font></b></p>
<p class=MsoNormal><b><font size=4 face="Times New Roman"><span
style='font-size:13.5pt;font-weight:bold'><o:p> </o:p></span></font></b></p>
<p class=MsoNormal align=center style='text-align:center'><b><font size=4
face="Times New Roman"><span style='font-size:13.5pt;font-weight:bold'><o:p> </o:p></span></font></b></p>
<p class=MsoNormal align=center style='text-align:center'><b><font size=4
face="Times New Roman"><span lang=EN-GB style='font-size:13.5pt;font-weight:
bold'>New Shortened Vertical for 17-20-30-40 Meters</span></font></b><span
lang=EN-GB><br>
August 19, 2006<o:p></o:p></span></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'><br>
Last night I tested my latest antenna: a 4-band, 20' vertical half wave that
uses two loading coils with taps. The results appear promising. On <st1:metricconverter
ProductID="20 meters" w:st="on">20 meters</st1:metricconverter> I worked a
<st1:State w:st="on"><st1:place w:st="on">Texas</st1:place></st1:State>
station. I was running 5 watts SSB and he used 800 watts. He had a rough copy
on me, but there was much fading at 10 p.m. Later, on 40 I had a couple of nice
CW chats to <st1:State w:st="on">California</st1:State> and <st1:State w:st="on">Louisiana</st1:State>
from here in <st1:State w:st="on"><st1:place w:st="on">Colorado</st1:place></st1:State>.
The antenna was only <st1:metricconverter ProductID="10 feet" w:st="on">10 feet</st1:metricconverter>
from the house and surrounded by tall trees - plus we have mountains on
three sides not far away. Halfway through the evening it started to rain. I was
sitting outside on a fabric-covered porch swing set up in the front yard and
stayed (mostly) dry. I'd started at 10:00 in the evening and finally
packed up around midnight after my last contact. It was getting chilly.<br>
<br>
The antenna is only 30% of full size on <st1:metricconverter
ProductID="40 meters" w:st="on">40 meters</st1:metricconverter>. It is a
compromise, but I designed it specifically for an upcoming vacation to the
mountain town of <st1:City w:st="on">Crested Butte</st1:City>, <st1:State
w:st="on"><st1:place w:st="on">Colorado</st1:place></st1:State> at the end of
this month. I will be staying in a 19-room lodge on the third floor with a
walk-out balcony, so I wanted something very portable and hard to see. Everything
is black: the pole, the antenna wire and I'll even painted the PVC support
black. A 20-foot fishing pole will hold the antenna, and a PVC base will
support it up against the hand railing. Because it is an electrical half
wave, it needs no counterpoise or radials, something that would be difficult to
set up on a tiny balcony. <br>
<br>
</span>Details follow each picture.<br>
<br>
<o:p></o:p></font></p>
<p class=MsoNormal align=center style='margin-bottom:12.0pt;text-align:center'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'><img border=0
width=373 height=315 id="_x0000_i1025" src="cid:image001.jpg@01C856E7.F98EAB50"
style='height:591px;width:700px' alt="efhwa_2111.jpg"><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span lang=EN-GB
style='font-size:12.0pt'>The antenna consists of three sections of wire and two
coils. The outer two wires are 4' 4-5/8" long, and the inner wire is 10'
8-3/4". I used 22-ga. <i><span style='font-style:italic'>stranded</span></i>
wire for both the antenna and the coil windings. I began making coils out of
stranded wire on the hunch that it would reduce some of the coil losses
due to skin effect. After several shortened halfwaves and a logbook full
of successful contacts, I discovered something called proximity efect that
negates any benefits to using stranded wire in coils. </span>Oh, well. I
continued the tradition here anyway.<o:p></o:p></font></p>
<p class=MsoNormal align=center style='margin-bottom:12.0pt;text-align:center'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'><br>
<br>
<img border=0 width=500 height=375 id="_x0000_i1026"
src="cid:image002.jpg@01C856E7.F98EAB50" style='height:375px;width:500px'
alt="coil_2107.jpg"><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span lang=EN-GB
style='font-size:12.0pt'>The coils are wound on 1-1/4" thin-wall
(schedule-20?) pipe and are about 3-3/8" long. After winding the wire, I
wrap everything in black electrical tape. <br>
There are four taps on each coil. The lowest tap on the coil (from right-to-left)
is for <st1:metricconverter ProductID="17 meters" w:st="on">17 meters</st1:metricconverter>,
followed closely by the <st1:metricconverter ProductID="20 meter" w:st="on">20
meter</st1:metricconverter> tap. Finally, the 30 and <st1:metricconverter
ProductID="40 meter" w:st="on">40 meter</st1:metricconverter> taps. The tap for
40 is actually one turn short of the full coil. I had intended to use the full
coil centered around 7.040 MHz and use the tap for the novice CW portion of the
band. During testing I discovered that the tap was a better fit, and the
additional wrap tested out below 7.000 MHz.<br>
<br>
Here are the windings for each band. The windings are based on a #22
stranded, insulated wire with an O.D. of 0.064" and approx. 15 turns per
inch. <br>
<u>Band / total turns</u><br>
17 m = 7.5 turns<br>
20 m = 13.5 turns<br>
30 m = 25.5 turns<br>
40 m = 46.5 turns<br>
Full coil = 47.5 turns (resonant below band edge - skip this turn)<o:p></o:p></span></font></p>
<p class=MsoNormal align=center style='text-align:center'><font size=3
face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'><br>
<br>
</span><img border=0 width=152 height=267 id="_x0000_i1027"
src="cid:image003.jpg@01C856E7.F98EAB50" style='height:500px;width:285px'
alt="base_2113.jpg"><o:p></o:p></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'><br>
Here is the PVC base I built for the high-mountain vacation and the top floor
balcony. The back leg and support is in case the balcony has a solid railing
with nothing to lash onto and it needs to be self-supporting. This photo was
taken before I had painted it "midnight black." The antenna will be
held up by a 20-foot fishing pole from Cabelas. The bottom of the pole will
slide down on the PVC. Everything breaks down to 45" or less - the length
of the fishing pole fully collapsed.<br>
<br>
</span><a href="http://n0lx.com/efhwa.html"><span lang=EN-GB>Here is the tuner
I use</span></a></font><span lang=EN-GB> for this and most of my half
waves. It's on the bottom half of the page. <br>
<br>
<b><u><span style='font-weight:bold'>August 30, 2006 update:</span></u></b>
This weekend I made a few contacts on 40 from the top floor balcony of a </span><a
href="http://www.n0lx.com/c_b.html"><span lang=EN-GB>mountain lodge</span></a><span
lang=EN-GB>. <br>
<br>
Tonight I set the antenna up in my front yard here in Golden, <st1:State w:st="on"><st1:place
w:st="on">Colorado</st1:place></st1:State>. It was 10:00 p.m. and I only had
time for one contact, so I talked to Ed, W7GVE in <st1:State w:st="on"><st1:place
w:st="on">Arizona</st1:place></st1:State> for almost 25 minutes. He was 589
and gave me a 569. Not bad for a seriously shortened antenna. </span>Here are
two shots taken in the dark.<o:p></o:p></p>
<p class=MsoNormal align=center style='margin-bottom:12.0pt;text-align:center'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'><img border=0
width=371 height=500 id="_x0000_i1028" src="cid:image004.jpg@01C856E7.F98EAB50"
style='height:500px;width:371px' alt=night1.JPG><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span lang=EN-GB
style='font-size:12.0pt'>What you don't see here are two huge trees on either
side of the antenna. It's amazing any RF escapes from this small yard. The
flash on my Canon G-2 really lights up the otherwise pitch-black night.<o:p></o:p></span></font></p>
<p class=MsoNormal align=center style='margin-bottom:12.0pt;text-align:center'><font
size=3 face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'><br>
<br>
</span><img border=0 width=364 height=543 id="_x0000_i1029"
src="cid:image005.jpg@01C856E7.F98EAB50" style='height:543px;width:364px'
alt=night2.JPG><o:p></o:p></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span lang=EN-GB
style='font-size:12.0pt'>On the table you can see the FT-<st1:metricconverter
ProductID="817, a" w:st="on">817, a</st1:metricconverter> <st1:place w:st="on">SLA</st1:place>
battery, headphones, a Palm Paddle, LED lamp and a UTC travel alarm clock. Above
the table is the matching unit taped to the PVC support. <br>
I've discovered a big advantage to CW. I can be outside late at night and not
wake up the neighbors sleeping with all their windows open as I might using a
microphone.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span lang=EN-GB
style='font-size:12.0pt'><br>
</span>.....</font><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p></o:p></span></font></p>
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