-16-
PRELIMINARY TUNING - DRIVEN ELEMENT
7. Check SWR on 12 meters. Adjust for lowest SWR at 24.900 MHz. This adjustment involves
sliding double clamp (KK) along rod (LL) and capacitor (FF) to find the right amount of inductance
and to raise or lower 12 meter resonance. If more travel along rod (LL) is required, loosen the end
of double-clamp (HH) and slide capacitor (FF) and clamp (KK) as needed towards the element
center to raise the lowest SWR frequency, or away from the center to lower it.
8.
Check the SWR on 17 meters. Tuning on this band is accomplished by varying the inductance of
the coil by sliding double-clamp (00) along capacitor (FF) and the coil lead, toward the center of the
element to raise frequency and in the opposite direction to lower frequency. Adjust for lowest SWR
at 18.070 MHz. If more travel is needed along the coil lead for clamp (00), loosen the large clamp
on capacitor (FF), and move capacitor (FF) in or out as needed.
9. Re-check SWR on the other bands to make sure that nothing has changed, and readjust as required.
This completes the near-ground tuning procedure for the driven element.
PRELIMINARY TUNING - REFLECTOR
The reflector element does not usually require any special attention because there are fewer circuits to
adjust and because the capacitors am carefully selected with respect to tolerance. The preliminary
settings given in the pictorial should suffice in most cases. On the other hand, miniature antennas are
inherently much more critical with regard to adjustment for best F/B ratio and SWR. On all but 20 meters
the HF5B would have to be adjusted in place for best possible F/B over a particular band segment, but the
consensus is that even with full size arrays of only two elements such exertions are seldom warranted
because the possible improvement is not too great to begin with.
If however, one wishes to adjust the 20 meter reflector tuning for lowest SWR at some particular
frequency refer to the pictorial diagram of the reflector. If tubular capacitor (EE) is moved closer to the
center of the element, the reflector will resonate at a higher frequency and the lower of the two dips in
the 20 meter SWR pattern will similarly move higher in the band. If capacitor (EE) is moved out to the
end of the clement, the resonance will drop to a lower frequency as will the lower dip in the 20 meter
SWR pattern.
A change of approximately 1/2 inch in the position of capacitor (EE) will shift the 20 meter resonance
approximately 50 kHz. Remember, however, that the two dips on 20 meters should be remain from 150
to 200 kHz apart for reasonably good F/B rejection and that similar readjustment to the driven element
may then become necessary.
FINAL ASSEMBLY
In the final assembly, the two elements will be installed on boom tube (R).
1.
Attach one boom to element plate (S) to each element using two 1" U-bolt (U), four 1/4" lock
washer (Z) and four 1/4" hex nut (AA) per element. Do not use backing clamp (X) with the 1" U-
bolt (U).
NOTE: BE SURE THAT BOOM TO ELEMENT PLATE (S) IS CENTERED ON THE ELEMENT
TUBE INSULATOR (B) AND DOES NOT SHORT TO EITHER ELEMENT TUBE (A)!
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