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Hustler BTV Series Trap Calibration Resonance Adjustment Procedure
(Trap Calibration adjustment may void your warranty with a new antenna.
Check with Newtronics or your dealer before you attempt.)

When resonance or low SWR dips are far from the correct frequency, use this coarse trap tuning adjustment procedure. Readjusting antenna resonance is easy. When desired tuning cannot be achieved by the adjustments in the Hustler manual, re-tuning the vertical for in-band resonance is best done by adjusting the traps. This is done just as you would on other parts of the antenna: by loosening a stainless clamp, making an adjustment and tightening the clamp again. However, trap adjustments produce a rapid frequency change with a slight movement of the trap sleeve. Follow the details of this procedure to make large frequency adjustments to the Hustler HF antenna.

The lengths in the table below
shows the initial bottom tube length of each trap as they usually come from the factory. Mark the position of the trap sleeve before you start so returning to the initial point will be simple if needed. This procedure should work fine for the 4BTV, 5BTV and 6BTV series antennas.





Hustler BTV trap

 

 

Old Style 

New Style (pictured above)

10 meters  10 1/16 inches

10 meters  9 1/8 inches

15 meters  9 1/4 inches

15 meters  8 1/8 inches

20 meters  10 7/8 inches

20 meters  10 inches

30 meters  12 inches

30 meters  10 3/8 inches


Note: The old style trap is identified by it's squared off bottom and is not tapered.


The lengths in the table above shows the initial bottom tube length of each trap as they usually come from the factory. Mark the position of the trap sleeve before you start so returning to the initial point will be simple if needed. Refer to the drawing as needed.

NOTE:

Start with the 10 meter trap first. (The first trap up from the bottom of the antenna).
The actual trap adjustment is made by disconnecting the main tubing section (known as the intermediate sections in the instruction manual), between each trap. This is done by loosening the SECOND adjustable clamp from the bottom of each trap. Then slide if off of the tubing that leads to the trap to be adjusted. The tubing extending from the inside of the trap is the length to be adjusted using the chart lengths above! The black area in the drawing above represents the tubing extending from the trap to the end of the tube. The total length from the end of the tubing to the point where it touches the trap housing is the length to be adjusted.

Just like other antenna adjustments, trap adjustments are not permanent and can be restored easily. Start with the 10 meter trap, (the one on the bottom in drawing), because any adjustment done there affects the rest of the antenna. Slightly loosen the clamp at the bottom of the trap sleeve, and then adjust the trap sleeve position on the trap bottom tubing using the chart above.
Typical adjustment is about 1/4 to 1/2 inch for a shift of 500 kHz. Firmly tighten the trap clamp and re-test with the entire assembled antenna upright to track the resonance or the SWR dip to the desired frequency. Once you adjust one trap, check all bands before deciding to recalibrate other traps.


Hustler BTV series antenna


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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