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Tuning the Vertical
It’s best to use an antenna analyzer for determining
antenna resonance. Use the X=0 or +/- j0 readings to
determine the resonant frequency. Later, the SWR will
be adjusted by the impedance matching assembly
mounted at the feed point once the vertical is resonant at
the desired frequency. Do not use the
DXE-VMN-1
for
changing the resonant frequency, initially tune the
antenna without the
DXE-VMN-1
(remove the
connection at the radial plate and isolate it. Do not let
the “L” bracket touch the radial plate).
The
60VE-1P
should resonate at approximately 5.368 MHz with the
DXE-VMN-1
at the feed
point, the recommended ground radial system installed and the vertical dimensions as shown in
Figure 11
. Resonance is adjusted by the length of the vertical sections.
If you are having trouble achieving resonance, make sure the tube section lengths are correct. Make
sure you have at least 16 radials (32 are better), 30 feet long, symmetrically placed around the
vertical. A very low SWR might indicate a poor ground radial system.
Connect the Tap Clip in the Base Matching Network at the 6th or 7th turn from the top as shown
and proceed as follows:
Adjust the tap clip by moving the tap clip to a different coil turn on the
DXE-VMN-1
Coil for minimum SWR on 60 meters. Disregard any
frequency shift of the points of lowest SWR on this band at this time.
Recheck the lowest SWR. If the SWR is higher move the tap clip on
the Base Matching Network Coil to a position that gives the lowest
SWR on 60 meters. Securely tighten the tap clip when done.
At full length, the 60 meter vertical antenna should resonate at
approximately 5.368 MHz with the VMN-1 impedance matching
assembly at the feed point and the recommended ground radial system. Resonance is adjusted by
the length of the vertical element sections.
The antenna resonant frequency may be centered at any point between these frequencies by merely
adjusting the overall length. To raise the base resonant frequency, shorten the element tubing stack.
Adjusting the vertical base measurement will move the resonant frequency 20 to 30 kHz.
Measurements are taken from the bottom of the base element tube to the first vertical element
section. To ensure sufficient nesting of the base tube, do not go beyond 29" of separation. The more
of the base element tube that is nested, the stronger the bottom section will be. For maximum
strength, the base section can be nested until it is slightly above the top clamp on the tilt-base. If a
larger excursion is desired, the antenna should be lowered and the length adjustment made to the
highest element section. As a rule of thumb, one foot of length should be approximately 50 kHz in
frequency. A shorter antenna length = higher frequency and a longer antenna length = lower
