Cushcraft HV4E Vertical Antenna
Version 0 13 2024 Cushcraft
CAUTION: Always start tuning on 40 meters and adjust each band progressively higher in
frequency. Adjustment of a lower frequency band will always have the most effect on the next higher
frequency band. The tendency of the interaction is that if you move one band higher ALL the other bands
move higher, but only very slightly. It is always best to "shoot for" the lowest end of the range you intend
to use, and "trim in" by adjusting the bottom loading assembly after the antenna is in it's final location.
ALWAYS work from the lowest frequency band up.
Tuning the Antenna
1. Measure and record the frequency where the lowest SWR occurs on for each band. The lowest
SWR should be at or below the bottom end of each HF band. The SWR should be below 2:1 at
resonance on each band.
2. The following is a typical chart for initial measurements of a new antenna before tuning:
40 M 1.3:1 about 6.97 MHz for 98” upper mast
20 M 1.2:1 about 13.7 MHz for 14” spoke
15 M 1.2:1 about 20.65 MHz for 10” spoke
10 M 1.4:1 about 27.1MHz for 8” spoke
If the resonant frequency is lower than what your equipment detected, take one spoke off to raise the
resonant frequency. Measure the resonant frequency and calculate the approximate resonant frequency
as if the spoke was in place using the chart on the below.
CAUTION:
Never trim the outer (rounded) end of the spokes. The sharp end that remains can be
a safety hazard and the power handling of the antenna will be greatly reduced on some bands.
IMPORTANT:
Due to the sensitivity of the resonant frequency on this antenna, small
increments, such as 1/4 inch, should be considered when cutting the spokes to find resonant
frequency.
Begin tuning by adjusting the 40 meter upper mast. Continue adjusting until the antenna resonates
approximately 15 KHz below the desired operating frequency.
Use the chart below to approximate the amount of spoke to be trimmed. Trimming only one spoke from
the top or bottom results in half the frequency change.
40 M: 1" reduction of upper mast equals approximately 32 KHz
20 M: 1" trimmed off each of the spokes equals approximately 323 KHz
15 M: 1" trimmed off each of the spokes equals approximately 525 KHz
10 M: 1" trimmed off each of the spokes equals approximately 437 KHz
3. Now tune progressively higher frequency bands by trimming the spokes. Do not cut off the
spokes from the rounded end.
Keep each set of capacitance spokes equal in size. 20 meters must be
the second HF band adjusted, 15 the third, and 10 meters last. After adjusting 10 meters go back and
check the other bands. Tighten all spoke screws. Remember the frequency of the adjacent frequency
bands will shift slightly as the next band is tuned.
Note the ground wire lengths may shift the resonant frequency as well as the best SWR.
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