-7-
CHECKOUT AND ADJUSTMENT
matching should suffice for operation over most of 80/75 meters provided the 80
meter coil is readjusted for each different band segment.
3. Determine the frequency of minimum VSWR on 40 meters. The coil setting given
earlier should produce resonance and lowest VSWR at approximately 7150 kHz.
The 40 meter VSWR and resonance curve may be shifted in the same manner as on
80/75 meters by changing the setting of the upper coil clamp of coil assembly
80/40 meter. On this band the setting is much less critical, and a 1 in (2.5 cm)
change in the clamp setting will shift the VSWR curve approximately 80 kHz. Be
sure to loosen the clamp around tube (E) that supports the 30 meter assembly and
to reposition it as needed to avoid distorting the 40 meter coil.
4. Check VSWR on 20 meters. Tuning is quite broad on this band because the
antenna is physically much taller than a quarter wavelength. To raise the
frequency of the lowest VSWR, reposition the 30 meter assembly so that the coil
support tube 30 meter L bracket (O1) can be replaced on the next lower turn of
the 40 meter coil. Alternatively, to lower the frequency of lowest SWR, reconnect
the coil support tube 30 meter L bracket (O1) to the next higher turn of the 40
meter coil. In some cases moving the tap point a full turn up or down may cause
more of a frequency shift than is desired, in which case the entire 30 meter
assembly may be rotated around tube (E) to permit adjustments of less than one
full turn.
5.
Check VSWR on 15 meters. The VSWR curve may be shifted upward or
downward by changing the length of the stranded wire between wire clamp
0.500" 15 M w/wire (L) and wire clamp 0.875" 15 M w/insulator (K). To raise the
frequency, simply shorten the wire by wrapping a longer tail back on itself and
sliding the lower clamp upward to maintain tension. To lower frequency, feed
more of the tail back through the hole in the insulator to increase the length of the
wire between wire clamp 0.500" 15 M w/wire (L) and wire clamp 0.875" 15 M
w/insulator (K). A change of 2 in (5.1 cm.) will shift the VSWR curve
approximately 300 kHz.
6.
Check VSWR on 10 meters. To raise the resonant frequency loosen the small hose
clamp over the slotted end of tube (I) and slide tube (J) farther into tube (I); to
lower the frequency, slide tube (J) farther out of tube (I) and retighten the hose
clamp. A length change of 3 in (7.6 cm) should move the VSWR curve
approximately 200 kHz.
7. Check VSWR on 30 meters. To raise frequency, loosen the wing nut on the
bottom coil clamp of coil/capacitor assembly 30 meter (P), stretch the coil and
retighten the wing nut. To lower frequency, compress the coil. A change of only
1/4 in (6.4 mm) will shift the VSWR curve approximately 100 kHz. Large changes
in the setting of coil/capacitor assembly 30 meter (P) may affect 20 and 40 meter
tuning, in which case it may be necessary to repeat steps 3 and 4. In general, the
point at which the 30 meter coil taps on to the 40 meter coil will be the major
factor in 20 meter tuning.
8.
Adjustments for 40, 30, 20, 15 and 10 meters should have little or no effect on
the previous adjustments for 80/75 meters, but a final VSWR check for this band
should be made as in step 1 above.
NOTE: In above-ground installations it will usually be found that
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