Force 12 Sigma-280 Magnum, Руководство по сборке

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DW-Manual-Sigma-280 Magnum-001 FORCE 12 SIGMA-280Magnum Assembly Instructions Page 8 of 32
III.
SIGMA-280 MAGNUM TUNING.
_____1)
The antenna will shift upwards as it is raised; however, it should not move more than 30
kHz up to a height of 70 feet when adjusted at a height of 20'. It is a good idea to make notes
on the shift as the reflector is tuned and raised. The reflector is tuned first and this will make
the driver simpler, as the shift will be known.
_____2)
Please refer to the photo pages.
_____3)
Use the U-bolts and saddles to secure the far end of the coils for initial tuning.
_____a) If it can be tuned at about 25-30' high, it should move only about 10 kHz
when raised to 75-90' high.
_____b) Increasing the spacing between turns on the two coils decreases the
loading and will raise the frequency.
_____c) Decreasing the spacing between turns on the 2 coils increases the loading and
will lower the frequency.
_____d) After securing the coils with the U-bolts, fine tuning can be done by
squeezing the turns together, or expanding them. After tuning, the coils are attached
permanently by drilling through the flat coil end and the boom, securing with ¼-20
hardware. The U-bolt and saddle can then be removed from each coil.
_____4)
While tuning, tape the covers and end caps to the element to prevent them from sliding out
of reach.
_____5)
If not already done, attach both elements to the boom and designate one as the driver and the
other as the reflector. The direction of maximum energy will be from the reflector, towards
and through the driver.
_____6)
The boom truss can be attached to the mast after the antenna is tuned and mounted on the
mast.
_____7)
Attach both relay boxes in parallel using the supplied 5-conductor wire. Only 4 conductors
are needed. Break the wire at the center for the supply and control line, then connect the
supply/control line and both cables to the boxes in parallel. Dress the leads to the boom.
_____8)
Connect a relay box to the element feed point on each element using the supplied (2) wires.
_____a) This connection is the “up” end of the box, when the barrier strip is on the bottom
right of the box and the hinge is on the left side.
_____b) Position the box so that the hinged door will be on the bottom when the relay box is
attached to the boom.
_____9)
Secure the boxes to the boom using the tie-wraps through the ears at the box corners. The
ears should be positioned for the best locating of the tie-wraps to the boom. Solid, stiff wire can also
be used to secure the boxes to the boom.
_____10)
The reflector element is tuned first.