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exactly solar noon. and the shadow ofa vertically
suspended line will be in the exact nonh
and south position.
To correct your standard time for your
location, consult a globe or an atlas to determine
the longitude of your antenna site. An
accuracy of about 15 minute!' of longitude
will be sufficient. The time correction to be
applied is equal toone minute oftime for each
15 minutes of longitude, or 4 minutes of lime
for each degree of longitude. The amount of
correction will be determined by the difference
in longitude between your antenna site
and the particular meridian of longitude on
which your local standard time is based. In
the U.S. , local EST is based on the 75th (75°)
meridian oflongitude. local CST is based on
the 91)0 meridian. local MST is based on the
105° meridian, and PST is based on the 120°
meridian. The 120° meridian passes through
Nevada, a few miles west of Reno. The
W6TYH antenna site is located on the 121°
meridian of lo ngilude; I'll use that location as
an example .
Standard times (EST, CST, MST, and
PST) are legal or official limes but are not
necessarily solar or sun limes. For example,
on June 16th ofany year, at 12:00 noon local
standard lime on any time-base meridian, the
sun will be directly overhead and the local
standard time and the solar time will be the
same. However, for a site located west ofthe
lime-base meridian. true solar noon will occur
at a lime earlier than the legal or official
time noon.
For example, W6TYH is located west of
the PST time-base meridian (120°). Therefore,
on June 16th of any year, true solar
noon will occur at the W6TYH antenna site al
exactly 12:04 p.m. PST. since I must add 4
minutes for each degree of longitude . If the
antenna site had been located on the 11 9 °
meridian. east of the time-base meridian, I
wou ld have had 10 subtract 4 minutes, and
true solar ooon would have occurred at 11 :56
a.m. PST (actually 12:56 MST, because the
119° meridian lies within the MST zone).
This lime correction is referred 10 as longirude
time correction.
The orbit ofthe earth around the sun actually
is not a ci rcle but an ellipse. You must add a
second correction because ofthe varying motion
of the earth in its orbit with respect to the
sun. The necessary corrections for various
dates throughout the year are calculated and
presented in Table 3. When the correction is
preceded by a plus sign, the correction should
be added 10 the local standard time. When the
correction is preceded by a minus sign, the
correction should be subtracted. This time
correction is referred to as seasonal lime
correction.
To illustrate the use of both the longitude
and seasonal time correction, let's
assume that the date on which the observation
is to be made is June 26th of any year.
Referring to Table 3, the seasonal time correction
for this date is found to be plus 2
minutes . Since you must add 4 minutes for
long itudinal time correction and another 2
minutes for seasonal lime correction (for a
total of 6 minutes), the exact instant of
" When You Buy, Say 73"
DESIGN EVOLUTION IN RF P.A.'s
Now with
GaAsFET
Preamp
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e Lmear (all mode) RF power amp with
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Amplifie r useable with drive powers
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• Rece ive preamp conoo. featuring GaAs
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weight is 5 Ibs.
Specilicationsfprk:e subiec! to change
true noon will occur at W6TYH on June 26
of any year at 12:06 pm PST. Note thai all
local times are standard and not daylight-saving
time.
Now that the preliminaries have been taken
ca re of and you have determined the exact
time of true solar ooon at your antenna site,
you can use this information to layout a true
north and south reference line through your
antenna site-from there you will be able to
determine accurately great-circle path directions
to any point on the earth. The accuracy
with which you are able to predict the point
on the globe where your antenna field will be
maximum will depend largely on your skill in
laying out the reference lines through your
antenna site and on a great-circle map or
globe.
For the next step. you'll need a perfect­
Iy straight piece of pipe about 6 to 10 feet
long. At the center of the antenna site , dig a
hole about 10 or 12 inches deep. Stand the
pipe in the hole and fill the hole with soil,
tamping it to hold the pipe upright; check it
with a carpenter's level to make sure thai is it
absolutely plumb (straight up and down). Tie
a nylon cord around the pipe and stretch il OUI
about 10 to 20 feet to the north . Watch the
time, and at the exact instant of true noon,
drive a rod or stake into the ground at the end
of the pipe' s shadow. Streich the co rd from
the pipe to the top center of the stake. The
cord is now stretched along your true northsooth
line.
2212G ,
4410G
441 2
4412G
(MHz) (WI (W) NF GAIN
5 170
0508G 50-54 170 6 15
170 10 6 15
160 10
160 10 6 15
reo so
160 30 6 15
130
, 130
10
10 7 12
130
''0
7 12
t
'00
100 11 12
1. Models wit h G suffix have GaAs FET preamps.
Non-G sulfix units have no preamp,
2. Covers tull amateur band. Specify 10 MHz
8an