POP itJ OH >10 METER OPERATION, INSERT

=CQ TO xMTft

TEST POINT A"

'B'-U^lV^ E lEG Ab 5 V£T£R LOMG WIRE FOR «KM-DIRECTIONAL AkTENNA EACH Of fOU* LOSES WAS ABOUT 2 43 SAlN ALSO CERATES ON 20 0« AO ME'iflS US!ti-j 10AO*MG f.Vi.

=CQ TO xMTft

TEST POINT A"

'B'-U^lV^ E lEG Ab 5 V£T£R LOMG WIRE FOR «KM-DIRECTIONAL AkTENNA EACH Of fOU* LOSES WAS ABOUT 2 43 SAlN ALSO CERATES ON 20 0« AO ME'iflS US!ti-j 10AO*MG f.Vi.

Fig 4

exact!) solar noon, and the shadow of a vertically suspended line will be in the exact north 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 minutes of longitude will be sufficient. The time correction to be applied is equal to one minute of lime for each 15 minutes of longitude, or 4 minutes of time for each degree of longitude. The amount of correction will be determined by the difference in longitude between your antenna site ;md the particular meridian of longitude on which your local standard time is based. !n the U.S.. local EST is based on the 75th (75°) meridian of longitude, local CST is based on the 90° 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 oí longitude; I'll use that location as an example.

Standard times (EST, CST, MST, and PST) are legal or official limes but arc not necessarily solar or sun times. For example, on June 16th of any year, at 12:00 noon local standard lime on any time-base meridian, the sun will be directly overhead and the local standard tune and the solar time will be the same. However, for a site located west of the time-base meridian, true solar noon will occur at a time 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, irue solar noon w ill occur at the W6TYH antenna site at 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 119° meridian, east of the time-base meridian, I would have had to subtract 4 minutes, and true solar noon would have occurred at 11:56 a.m. PST (actually 12:56 MST, because the 119° meridian lies within the MST zone). This time correction is referred to as longitude time correction.

The orbit ofiheearth around the sun actually is not a circle but an ell ipse. You must add a second correction because of the 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 to the local stani iard time. When the correction is preceded by a minus sign, the correction should be subtracted. This time correction is referred to as seasonal time 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 3t the seasonal time correction for this date is found to be plus 2 minuies, Since you must add 4 minutes for longitudinal time correction and another 2 minutes for seasonal time correction (for a total of 6

minutes), the exact instant of

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