After trap adjustment
above, now you can fine tune the antenna if needed using
the
intermediate tubing sections represented by "Y" in the above
drawing.
Increasing dimension Y below each
respective trap (see drawing above), results in a lower resonant
frequency. (This has the same effect as lengthening a dipole element to
make it resonant at a lower frequency).
Decreasing dimension Y results in a higher frequency. (Same effect
as in a dipole element).
Fine tune by adjusting the tubing position
dimensions, designated by letters, described in the Hustler instructions.
These sections are designated as "intermediate tube sections"
in the
Hustler manual.
Do not worry if you cannot tune the antenna to the
lowest possible SWR of 1.0:1. An SWR of 1.4:1 to 1.6:1 SWR range is only a
3% to 5% power reflection, which is an acceptable operating SWR for HF
Amateur operation. Information is available, in the Tech
Info Articles at http://www.dxengineering.com/, about using an impedance matching shunt coil to reduce high
SWR on 40 and 80 meters.
Additional information for Trap
Calibration
Hustler BTV antennas can resonate
at frequencies much lower than desired, when installed on very good soil
or with a good radial system. Most Hustler BTV series antennas come from
the factory adjusted for use WITHOUT RADIALS and ground mounted. A
high efficiency quarter-wave vertical requires a good radial
system.
You will get your best overall
performance with plenty of radials.
Installation and
tuning solutions with few or no radials will result in poor efficiency
from high ground losses. Since most Hustler BTV series antenna come from
the factory with traps adjusted for use without radials,
then some readjustments of traps for your location
may be needed if the intermediate tubing adjustments won't get the
resonance or swr frequency range where you need it.
Trap Calibration
adjustment may void your warranty with a new antenna. Check with
Newtronics or your dealer before you attempt. Make certain you give them
all your installation details.
Never Cut The
Aluminum Tubing: You can’t properly
adjust the resonant frequency of the antenna by cutting the traps or by
cutting the aluminum tubing above or below the traps.
An antenna analyzer is the best tool to use for
adjusting the resonant frequency of an antenna. Use a 5 or 6 foot piece of
50 Ohm coax between the antenna and the analyzer. Your body presence can
affect the tuning if you are too close to the antenna as will other very
close conductive objects. If you are too far, the coax may act as a radial
and resonate.
Tune the antenna for resonance (minimum reactance, X=0)
rather than for low SWR, although they may be close or at the same point.
If you only have an SWR/power meter, you should plot a chart of SWR
measurements at several frequencies within each band. Start at the lowest
frequency of the SWR curve and record measurements upward at frequencies
through the entire SWR curve. When making antenna adjustments, DO NOT try
to shoot for a minimum SWR by watching a certain frequency. You might
"miss the dip" as it passes your target frequency. It is a much better
practice to follow the minimum SWR point as you make adjustments, to
achieve resonance at the correct frequency.
As with other antenna adjustments, some
trial and measurement may be needed.
(Thanks to Del,N7ATA for
relaying this info to us)
Credit to
Newtronics (Hustler) and
DX Engineering for making
this information possible.
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