Butternut BUT-HF6V User manual

Butternut®HF6V
80/40/30/20/15 and 10 Meters
Six-Band
Vertical Antenna
BUT-HF6V
BUT-HF6V-INS-Revision 1a
© Butternut 2016 Artists rendition of an installation
1200 Southeast Ave. - Tallmadge, OH 44278 USA
Phone: [phone] ∙ Tech Support and International: [phone]
Fax: [phone]

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Introduction
The classic Butternut®HF6V 6-band vertical antenna operates on 75/80, 40, 30, 20, 15 and 10
meters. Designed with corrosion-resistant aluminum tubing, this antenna is very durable and
attractive.
The first L/C circuit generates enough reactance to bring the whole HF6V to resonance on 80
meters allowing it to act as a 1/4-wave radiator. It also generates enough capacitive reactance to
produce another discrete resonance at about 11 MHz. The second, 40 meter L/C circuit generates
enough reactance to resonate the whole HF6V allowing it to act as a 1/4-wave radiator. In order to
minimize conductor and I²R losses an 80 and 40 meters where the antenna is physically shorter than
a 1/4-wave and thus operates with lower values of radiation resistance, large-diameter Hi-Q self-
supporting inductors and low loss ceramic capacitors are employed.
Where the height of the HF6V is slightly greater than a 1/4-wave on 30 meters, an L/C series tuned
circuit taps onto the 40 meter coil for the extra inductance to pull the earlier 11 MHz secondary
resonance down to 10 MHz. At the same time, a portion of the 40 meter coil is shorted out which
allows the circuit to resonate on 30 meters The addition of this circuit also produces additional
resonances at 14 MHz and 28 MHz.
On 20 meters the entire radiator operates as a 3/8-wave vertical with much higher radiation
resistance and VSWR bandwidth than conventional or trapped antennas having a physical height of
1/4-wave or less. Because the 20 meter radiation resistance will be several times as greater as that of
conventional vertical antennas, an electrical 1/4-wave section of 75 ohm coax is used as a geometric
mean transformer to match the approximate 100 ohms of feedpoint impedance on that band to a 50
ohm main transmission line of any convenient length.
The HF6V operates as a slightly extended 1/4-wave radiator on 15 meters, a 1/4-wave stub de-
coupler providing practically lossless isolation of the upper half of the antenna on that band.
On 10 meters the HF6V becomes a 3/4-wave radiator with considerably greater radiation resistance
and efficiency than 1/4-wave trapped verticals.
Features
Full band coverage for 80, 40, 30, 20, 15 and 10 meters
Height is 26 feet
Weight is only 14 pounds
Feedpoint Impedance is a nominal 50 ohms through the included matching line
Power handling up to 1,500 W full legal limit on 80/40/20/15/10M, 500 W PEP on 30M
Wind load 2 ft2(80 mph survivability - no ice)
VSWR at resonance: 1.5 or less on all bands
Bandwidth for VSWR 2:1 or less: 30/20/15/10M - entire band.
Bandwidth for VSWR 2:1 or less: 140-150 kHz on 40M, 25-30 kHz on 75/80M
Requires radial system

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WARNING!
INSTALLATION OF ANY ANTENNA NEAR POWER LINES IS DANGEROUS
Warning:Do not locate the antenna near overhead power lines or other electric light or power
circuits, or where it can come into contact with such circuits. When installing the antenna, take
extreme care not to come into contact with such circuits, because they may cause serious injury or
death.
Overhead Power Line Safety
Before you begin working, check carefully for overhead power lines in the area you will be
working. Don't assume that wires are telephone or cable lines; check with your electric utility for
advice. Although overhead power lines may appear to be insulated, often these coverings are
intended only to protect metal wires from weather conditions and may not protect you from electric
shock. Keep your distance! As a suggestion, remember the 10-foot rule; when carrying and using
ladders and other long tools, keep them at least 10 feet away from all overhead lines - including any
lines from the power pole to your home.
There are parts made from fiberglass in this kit. Take normal precautions when handling any
fiberglass material. There may be fiberglass dust, slivers or particles present when the fiberglass
parts were manufactured. The use of typical fiberglass handling safety gear (gloves, dust mask, eye
shield, clothing, etc.) when handling and working with fiberglass is recommended. Use a damp rag
to wipe the parts. Do not use compressed air to clean fiberglass parts. Measures can be taken to
reduce exposure after a person has come in contact with fiberglass. Eyes should be flushed with
water and any area of exposed skin should be washed with soap and warm water to remove fibers.
Clothing worn while working with fiberglass should be removed and washed separately from other
clothing. The washing machine should be rinsed thoroughly after the exposed clothing has been
washed. Check with your local or state safety and/or environmental agencies for more detailed
precautions.
Tools Required
Straight Slot Screwdriver
Phillips Head Screwdriver
1/4” Nut Driver or socket set
11/32” Nut Driver or socket set
3/8” Nut Driver or socket set
Tape measure
Pencil

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Additional Material Needed But Not Supplied
Jet-Lube™SS-30 Aniti-Oxidant Corrosion Inhibiting Lubricant
Ground Rod installed near base of the antenna
Suggested Parts Not Included
Radial Wire Kits and Components - There are optional Radial Wire Kits available.
Guying Kit for Vertical Antennas - Some vertical antenna manufacturers indicate their antennas
do not need guying. During times of high winds or ice loading, some of these vertical antennas may
sustain damage or fail altogether. With the small amount of effort needed to install a four point
guying system, the risk hardly seems worth taking. A four-point guying scheme provides the best
mechanical advantage to reduce wind stress, regardless of direction. Information on guying the
Butternut®HF6V is included in this manual. Information on guying the Butternut®HF6V can be
found in the section “Guying the HF6V Antenna”.
BUT-GRK Ground Radial Kit for ground mounting - 160 thru 6 meter operation
BUT-RMK-II Roof Mounting Kit for roof mounting - 80 thru 6 meter operation
Site Selection
Ideally, select a mounting location clear from power lines, structures and other antennas by a
minimum of 45 feet. Consider overhead power lines, utility cables and wires. The vertical should
be mounted away from local noise sources or other metallic objects which can re-radiate noise and
affect the tuning, radiation pattern and SWR. Determine the direction you want the antenna to tilt
down and make sure there is adequate clearance (at least 45 feet). There should also be a clear
diameter of 70 to 130 feet from the antenna for the guying and radial systems that will extend away
from the antenna. As with all Amateur Radio antennas there maybe compromises and the ideal site
may not be available.

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Mounting Tube (A) Installation
When the bottom tube with insulator (A) is ground mounted, it should be protected against
corrosion if placed in concrete, damp acidic or alkaline soil. Asphalt roofing compound,
polyurethane varnish or other sealant that protects against moisture may be used. Concrete may be
used in areas of high winds for greater strength, in which case the post may be twisted slightly
during setting for easy removal later. Ensure it is not mounted at an angle. You want the antenna to
be vertical when fully installed. To help maintain the antenna base, place a larger diameter metal
tube, such as the BUT-MPS Mounting Post Sleeve in the ground, then you can slip tube w/insulator
(A) in and it will be protected from direct contact with the concrete.
Tube with insulator (A) must be installed in a hole approximately 21 inches
deep so that the upper end of the fiberglass insulator is approximately 7 inches
above ground level. Pack earth tightly around tube w/insulator (A) so that it
remains vertical. When installed, you want the top of tube A at 2-3 inches or
less above ground level to keep the feedpoint below 5” above ground level.
NOTE: HAMMERING TUBE W/INSULATOR (A) INTO THE EARTH
MAY CAUSE THE INSULATOR TO SPLINTER. If the post must be hammered into the earth,
protect the end of the insulator with a block of wood
NOTE: DO NOT USE U-BOLTS TO ATTACH TUBE W/INSULATOR (A) TO A MAST,
TOWER ETC. WITHOUT ADDED PROTECTION. U-BOLTS WILL EVENTUALLY CUT
INTO THE TUBING AND WEAKEN THE INSTALLATION. If U-bolts are used, place a larger
diameter metal tube, such as the BUT-MPS Mounting Post Sleeve over tube w/insulator (A).
Similar precautions should be observed when using TV style towers with locking bolts.
The BUT-RMK-II Roof Mounting Kit includes the BUT-MPS as well as the BUT-STR-II Stub
Tuned Radial Kit.
Radial System
The use of a radial system is a key requirement for any high performance quarter wave vertical
antenna system. With any vertical antenna system, the radials are the second half of the
antenna. The radials contribute to the radiation efficiency of the entire vertical antenna
system.
The exact number of radials required for low SWR and reasonably efficient operation will depend
in large measure on local earth conductivity, and this may vary considerably from one place to the
next and from one frequency band to the next. For most installations the soil conditions will be
poor to very poor when it comes to conductivity.
The best procedure is to assume that most earth is a poor conductor over the HF range and that
some radial wires will be needed. Radials may be placed on the surface of the earth or buried
slightly below the surface to get them out of the way, and their length is largely a matter of

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convenience. In general, a large number of short radials are preferable to a small number of longer
radials for a given amount of wire, especially if fewer than a dozen radials are to be used. Unlike
resonant radials that must be cut to the proper lengths for use with elevated verticals, ground-level
radials need not to be cut to any particular length; their sole purpose is to provide less lossy return
paths for currents flowing along the earth than the earth itself can provide. And, since "return"
currents will be flowing back to the antenna from all points of the compass, the radial wires should
be spaced uniformly over 360 degrees, although physical circumstances will often make this "ideal"
distribution impossible. For a discussion of ground system for elevated verticals, see the section
entitled "Above Ground Installations" following Checkout and Adjustment instructions.
At a minimum, 20 radials, each 32 feet long, may be used with this antenna. Using 32 radials at 65
feet long are preferred and highly recommended for the best performance on 80 meters with this
antenna. The extra radials help overcome unknown poor-soil conditions, improve bandwidth, and
ensure the best performance efficiency possible from the Butternut®HF6V antenna. Radial Wire, a
14 gauge stranded copper with black relaxed PVC insulation wire is suggested for the best results
for ease of installation and being able to withstand foot traffic over the radial wires without
breaking smaller gage wires.
The wire radials should placed as symmetrically as possible
straight from the feedpoint around the vertical antenna and spaced
evenly, regardless of how many radials are used. Do not cross or
bunch any radial wires as this nullifies their effectiveness. If you
have limited space, put in as many straight radials as you can. The
radials must be connected to the shield of your feedline. A
Stainless Steel Radial Plate is the ideal optional item which
provides an excellent system for attaching radial wires to your
vertical antenna system.
Radial wires can be laid on the roots of the grass or on bare ground
using Radial Wire Anchor Pins to hold them down. Using enough
staples will ensure the wires will not be snagged by mowers, people, or animals. Depending on
where you live and the type of grass you have, grass will quickly overgrow the radials and it will be
virtually impossible to see them. Radials can also be buried just under the surface (approximately 1”
- anything deeper and you will start losing effectiveness) by using a power edger to make a slit in
the soil.
NOTE: The function of a ground rod is to place the antenna at D.C. ground potential. It cannot
take the place of an effective RF ground system, such as a number of radial wires, regardless of its
depth in the earth. It does, however, serve as a convenient tie-point for such radials, as does the bolt
through mounting post w/insulator (A) to which radials can be connected by means of the remaining
#8 hardware.

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The Optional Radial Plate
A stainless steel Radial Plate is an ideal option for the radial system that is needed for the
Butternut®HF6V vertical antenna. The radial plate can be set on the ground. When the antenna is
installed, run a short piece of copper strap from the radial plate to the lower connection of coil Q
mounted on tube (A) of the HF6V or the optional BUT-MPS Mounting Post Sleeve. In either case,
a ground wire attachment from the lower tube (A) to the Radial Plate should be made to ensure a
good RF connection.
Radial Plate shown installed.
Aluminum Tubing Information
When assembling any telescoping aluminum tubing sections you should take the following steps:
1. Make sure the edges are smooth and not sharp. Deburring may be necessary, since burrs and
shavings can occur on seams as well as edges. All surfaces need to be completely smooth to
allow easy assembly of tubing sections.
Caution
Aluminum tubing edges can be very sharp.
Take precautions to ensure you do not get accidentally cut.
The raised particles and shavings that appear when the aluminum tubing is machined are
referred to as burrs, and the process by which they are removed is known as deburring.
The aluminum tubing supplied with this antenna is machine cut on both ends and machine slit
on one end. You should further assure that there are no ragged edges or protrusions.

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2. Clean the inside of the aluminum tubing to clear out any dirt or foreign material that would
cause the aluminum tubing sections to bind during assembly. Do not use any type of oil or
general lubricant between the aluminum tubing sections. Oils or general lubricants can cause
poor electrical connections for radio frequencies.
3. Clean the outside of the aluminum tubing to clear any dirt or foreign material that would cause
the clamps to malfunction during assembly.
4. The use of Jet-Lube™SS-30 Pure Copper Anti-Seize is highly recommended. Jet-Lube™SS-
30 is an electrical joint compound which effects a substantial electrical connection between
metal parts such as telescoping aluminum tubing or other antenna pieces. Using Jet-Lube™SS-
30 assures high conductivity at all voltage levels by displacing moisture and preventing
corrosion or oxidation.
5. When assembling the aluminum tubing sections, ensure the area is clear of grass, dirt or other
foreign material that could cause problems during assembly of the closely fitted telescoping
sections.
Assembly
Note: For reference purposes, a completed HF6V Antenna is shown at the end of this
manual following the complete detailed parts list.
Note: Jet-Lube™SS-30 Anti-Oxidant should be used between all antenna element sections.
Jet-Lube™SS-30 is an electrical joint compound to affect a substantial electrical
connection between metal parts such as telescoping aluminum tubing or other antenna
pieces. It ensures high conductivity at all voltage levels by displacing moisture and
preventing corrosion or oxidation.
Jet-Lube™SS-30 should also be used on all coil clamps, element clamps, bolts and
stainless steel threaded hardware to provide good electrical contact, prevent galling,
allowing easier disassembly and to ensure proper tightening.

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1. Check to be sure that no parts are missing (see assembled antenna pictorial page)
2. If the antenna is to be installed at ground level, plant mounting tube (A) in a hole approximately
21 inches deep so the upper end of the fiber rod insulator (feedpoint connection) is
approximately 3 inches or less above ground level. Ensure it is not installed at an angle. You
want the antenna to be vertical when fully assembled.
Pack earth tightly around mounting tube (A) so that it will remain vertical. Concrete may be
used in areas of high wind for greater rigidity, in which case the mounting tube should be
rotated while the concrete is setting so that it may be easily removed later. If the antenna is to be
mounted in concrete or in damp, acidic or alkaline soil, the
mounting tube should be given a protective coating of asphalt
roofing compound, polyurethane varnish, or another suitable
covering to protect the metal against corrosion. You may also
want to use the optional BUT-MPS Mounting Post Sleeve which
fits over tube (A) to help protect it from contamination.
NOTE: DO NOT HAMMER THE MOUNTING POST INTO THE GROUND AS THIS
CAN SPLINTER THE FIBER ROD INSULATOR AND COMPLICATE
INSTALLATION.
Note: Step 3 starts the antenna assembly minus Tube A (with insulator). The antenna assembly
will be mated to tube (A) when ready to be installed for final assembly steps. In all subsequent
steps, assembly should be done indoors or in an area where dropped hardware may easily be
recovered.
3. Locate Tube (B) and (B1). Slide the insulator on tube (B1) into the top of tube section (B) and
secure with a #8 x 1-1/2" bolt, #8 lock washer and #8 hex nut.
Tube (B) 1-1/8” x 48” long Tube (B1) 1-1/8” x 12” with insulator
NOTE: Tube (B) has the mounting hole located 1/4" from the end.
CAUTION: IF A FLAT BLADE SCREWDRIVER IS USED - NEVER HOLD THE WORK
OPPOSITE THE BLADE IN ORDER TO AVOID POSSIBLE INJURY IN CASE THE
BLADE SLIPS

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4. From the center of the insulator, measure downward to a point that is 13”along tube (B) and
make a pencil mark.
5. From the center of the insulator, measure upward to a point that is 9-3/8" along tube (B1) and
make a pencil mark.
Note: Jet-Lube™SS-30 Anti-Oxidant should be used on all coil clamps, element clamps, bolts
and stainless steel threaded hardware to provide good electrical contact, prevent
galling, allowing easier disassembly and to ensure proper tightening.
6. Locate coil assembly 80/40 meter (C) and slide the clamp at the outer end of the larger 80 meter
coil over tube (B1), lowering the entire assembly until the middle clamp can be positioned
around the insulator between tube (B) and tube (B1). NOTE: The middle clamp may have to be
pulled open slightly to pass the bolt that goes through tube (B1) and the insulator.
7. Position the center coil clamp of coil assembly 80/40 meter (C) in the center of the insulator
between tube (B) and tube (B1). Pass a #10 x 1" screw through the clamp as shown. Secure with
a flat washer, lock washer and wing nut. NOTE: The outer tab of this clamp may be bent back
slightly to provide clearance for the bolt, bending it back into place after assembly.
8. Stretch the 40 meter (smaller) coil on the coil assembly 80/40 meter (C) until the top of the
upper clamp is even with the upper mark. Secure with a #10 flat washer, lock washer and wing
nut.

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9. Stretch the 80 meter (larger) coil on the coil assembly 80/40 meter (C) until the bottom of the
lower clamp is even with the lower mark. Secure with a #10 flat washer, lock washer and wing
nut.
10. Locate the capacitor assembly 80/40 meter (D) and install capacitor bracket 80 meter (D1) on
the larger 200 pF capacitor using the installed screw.
NOTE: DO NOT USE EXCESSIVE FORCE OR OVER TIGHTEN THE SCREWS ON EITHER
CAPACITOR AS YOU WILL DAMAGE THEM. DO NOT DROP THIS ASSEMBLY AS
YOU MAY FRACTURE THE CAPACITOR’S CERAMIC SHELL.
11. Locate capacitor bracket 40 meter (D2) and install on the smaller 67 pF capacitor as shown.
12. Install the above assembly onto the #10 screw protruding from the tab of the center clamp on the
coil assembly 80/40 meter (C). Align capacitor bracket 80 meter (D1) alongside the larger 80
meter coil of coil assembly 80/40 meter (C). Secure with a #10 flat washer, lock washer and hex
nut.
13. Attach the tab end of capacitor bracket 80 meter (D1) to tube (B) with capacitor bracket clamp
(U) and secure with # 8 x 1" screw, lock washer and a hex nut.
14. Attach the tab end of capacitor bracket 40 meter (D2) to tube (B1) with capacitor bracket clamp
(U) and secure with # 8 x 1" screw, lock washer and a hex nut.

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15. Insert the un-slotted end of tube (E) into tube (B1) and secure with a # 8 x 1-1/2" screw, lock
washer and hex nut.
16. Locate coil support tube 30 meter (O) and measure to a point 9-7/8” down from the end of the
plastic insulator. Mark this point with a pencil.
17. Locate coil support tube 30 meter L bracket (O1) and place the tabbed end inside of the coil
support tube 30 meter (O) securing it with a # 8 x 3/4" screw, lock washer and hex nut.
18. Place a #10 washer, lock washer and wing nut on the lower single clamp of coil/capacitor
assembly 30 meter (P).
19. Place a #10 washer, lock washer and hex nut on both upper clamps of coil/capacitor assembly
30 meter (P).
20. Pass the lower single clamp of coil/capacitor assembly 30 meter (P) over the insulator end of
coil support tube 30 meter (O) and slide the coil downward along the tube until the upper edge
of the upper clamp is flush with the end of the insulator. Align the upper clamp with the coil
support tube 30 meter L bracket (O1) and tighten the hex nut.
21. Stretch the coil until the bottom of the bottom clamp on the coil/capacitor assembly 30 meter (P)
is even with the 9-7/8” mark on coil support tube 30 meter (O) and tighten the wing nut.

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22. Slide the remaining clamp from the above assembly over tube (E) and position it so the coil
support tube L bracket (O1) is even with fourth turn, counting from the top of the 40 meter coil
on the coil assembly 80/40 meter (C) and tighten the hex nut.
23. Hook the coil support tube 30 meter L-bracket (O1) around the fourth turn of the 40 meter coil
on coil assembly 80/40 meter (C). Secure with a # 8 x 3/4" screw, lock washer and hex nut.
Steps 24 through 29 are for installing the 15 meter parts to the antenna. Use the following
diagram to assist in identifying the parts and their proper locations:
24. Position wire clamp 0.875" 15M with insulator (K) around tube (F) and use a # 8 x 1" screw,
lock washer and hex nut finger tight. Final adjustment will be done in a later step.
25. Insert the un-slotted end of tube (G) into the slotted end of tube (F) and secure with a # 8 x 1-
1/4" screw, lock washer and hex nut.

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26. Locate wire clamp 0.750" 15M with insulator (N) and position it around tube (G). Final
tightening and positioning will be done in a later step.
27. Insert the un-slotted end of tube (H) into the slotted end of tube (G) and secure with a # 8 x 1"
screw, lock washer and hex nut.
28. Locate wire clamp 0.625" 15M with insulator (M) and position it around tube (H). Final
tightening and positioning will be done in a later step.
29. Insert the un-slotted end of tube (I) into the slotted end of tube (H) and secure with a # 8 x 1"
screw, lock washer and hex nut.
30. Position wire clamp 0.500" 15M with wire (L) around tube (I) so the top edge is 13-1/2”from
the upper end of the tube.
31. Measure from the rivet of wire clamp 0.500" 15M with wire (L) to a point 11 feet 3 inches along
the stranded wire and mark this point.

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32. Pass the free end of the stranded wire from wire clamp 0.500" 15M with wire (L) through the
small holes in wire clamp 0.625" 15M with insulator (M) and wire clamp 0.750" 15M
w/insulator (N) as shown.
33. Loop the end of the wire through the hole in wire clamp 0.875" 15M with insulator (K) sliding it
on tube (F) until the mark on the wire appears. Wind the wire back on itself. Do not cut off the
excess wire.
34. Line up wire clamp 0.875" 15M with insulator (K), wire clamp 0.750" 15M with insulator (N)
and wire clamp 0.625" 15M with insulator (M) with wire clamp 0.500" 15M with wire (L) and
tighten all clamps making sure the wire is moderately taut but not enough to cause the upper
tubing section to bow. Once tuning is complete, cover the end of the 15M wire with Scotch®
Super 33+ tape to keep water from entering the wire.
35. Place the protective cap (T) on one end of tube (J).
36. Slide the uncapped end of tube (J) into the slotted end of tube (I) until 25 inches extends out
from the end of tube (I) and secure with the small adjustable element clamp (V).
NOTE: In the following steps the antenna will be assembled and raised to its full vertical height. If
the antenna is to be installed in an elevated position where it is unsafe or inconvenient to make
in-place adjustments, the antenna may have to be installed in one piece. It will probably be
necessary to raise and lower it and its supporting structure a number of times to arrive at the
ideal adjustment on all bands. If so, every precaution should be observed in order to avoid
possible contact with power lines and to prevent structural failure that can cause injury to
persons or property.
WARNING: AVOID POWER LINES!
37. Place the lower end of tube (B) through tube (E) over the insulator on tube (A) with insulator.
Line up the holes and secure it with a # 8 x 2" screw, lock washer and hex nut.
38. Raise the assembly of tube (F) through tube (J) and slide the lower end into tube (E) fastening it
securely with a # 8 x 1-1/4" screw, lock washer and hex nut.

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39. Install coax 75 ohm matching (R) as shown placing the lug from the center conductor over the
screw on tube (B) and the braid over the screw on tube with insulator (A). To aid in eliminating
water damage of the coax, run it so the terminals are facing downward so water will drip down,
not toward the coaxial cable.
40. Place # 8 washers over each screw and install coil (Q) base matching. Secure with washers, lock
washers and hex nuts.
NOTE: Attach radials and ground to tube with insulator (A) using the remaining # 8 hardware on
the ground side (lower side) of the coaxial cable connection.
WARNING: MAKE SURE THAT THE STATION EQUIPMENT IS CONNECTED TO A
GOOD EARTH GROUND! DO NOT HANDLE CABLE CONNECTED TO STATION
EQUIPMENT WITHOUT FIRST DISCONNECTING THE EQUIPMENT FROM THE
POWER MAINS. YOU COULD BE ELECTROCUTED!
41. Connect the 75 ohm matching (R) coaxial cable to any
length of 50 to 53 ohm coaxial cable that goes to your
transmitter. At the end of the 75 ohm matching cable there
is a double female UHF Connector provided.

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Checkout and Adjustment
Adjustments will have to be made before trying to transmit with this antenna system. Installations
vary considerably and there are no ‘set’ measurements that will work for all the variables in the
installation. The dimensions and coil settings that were used during assembly are somewhat close
and may produce reasonably low VSWR readings over the entire 10, 15, 20 and 30 meter bands and
over at least 250 kHz of the 40 Meter band. Bandwidth on 80/75 meters should be at least 30 kHz
for VSWR of 2:1 or less at the low end of the band and may be as much as 100 kHz at the high end
of the band, depending on the efficiency of the ground system used, greater bandwidth being
associated with lossy ground systems. It should be remembered that on those bands where the
physical height of a vertical antenna is less than a quarter wavelength, the earth (or the resonant
radial system in above-ground installations) will have a good deal to do with VSWR and antenna
tuning, bandwidth and overall performance.
Low VSWR by itself does not mean that a vertical antenna is operating efficiently, and if low
VSWR is obtained with no more than the usual quick and dirty ground connection, it most likely
means the opposite. In general, poor operation or improper tuning of vertical antennas can usually
be attributed to inadequate (or even reactive) ground systems or to other vertical conductors in the
vicinity of the antenna. For these reasons it is suggested that the antenna be placed as much in the
clear as possible and used with the best ground system that conditions permit. For a more complete
discussion of the interrelationships between vertical antenna efficiency, bandwidth, VSWR, etc., a
standard text such as the A.R.R.L. Antenna Book is recommended. See also the additional material
included at the end of these instructions.
For adjustment purposes a simple VSWR indicator may be used. More accurate measurements may
be made at the antenna (i.e., at the junction of the coax 75 ohm matching (R) and the main
transmission line) than at the input end of the line, but the tuning conditions that exist at the
transmitter will usually be of greater interest in that one's principal concern will be to couple power
from the transmitter into the transmission line.
1. Check VSWR on 10 meters. To raise the resonant frequency loosen the small 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 small clamp. A
length change of 3 inches should move the VSWR curve approximately 200 kHz.
NOTE: you can measure then adjust both 10 and 15 meters at the same time since they don’t
interact like other band adjustment. This may help save some time and effort when tuning.
2. 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" 15M with wire (L) and
wire clamp 0.875" 15M with 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.

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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" 15M with wire (L) and wire clamp 0.875" 15M
with insulator (K). A change of 2 inches will shift the VSWR curve approximately 300 kHz.
3. Determine the frequency at which VSWR is lowest on 80/75 meters. The coil setting given
earlier should produce resonance and lowest VSWR at approximately 3700 kHz.
To raise the frequency of resonance of the lowest VSWR, simply loosen the wing nut on the
lower coil clamp of the coil assembly 80/40 meter (C) coil on tube (B) and stretch the coil a bit
more.
To lower the frequency, compress the coil. A One inch change in the setting of this coil will
produce a frequency shift of approximately 125 kHz.
NOTE: Remember that the antenna tunes very sharply in this range and that high values of VSWR
may be encountered only a few kHz either side of the lowest VSWR readings, so it would be
well to take VSWR readings every 25 kHz or so to avoid running past the frequency of
resonance and lowest VSWR.
NOTE: To minimize interference to other stations and to avoid erroneous reading use only enough
power to produce full-scale deflection of the meter in the forward or R.F. out position.
4. Once the proper coil setting has been found for the desired band segment, coil (Q) base
matching at the base of the antenna may be adjusted for even lower VSWR. If earth losses are
moderate to high a good match may be possible if coil (Q) base matching is left fully
compressed; if earth losses are low (as with an extensive radial system) coil (Q) base matching
may have to be stretched to twice its compressed length or more for a good match. In any case, a
single setting for coil (Q) base matching should suffice for operation over most of 80/75 meters
provided the 80 meter coil is readjusted for each different band segment. Note that coil Q will
have to be cut to remove turns and stretch the coil. The combination of cutting and stretching
should be such to keep the dimensions of the coil reasonable and strong mechanically. Most
installations will have to stretch and remove turns considerably. As you make the adjustments,
check your VSWR, note that you CAN, and should get it down to 1:1.
5. 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 inch 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.
6. Check VSWR on 20 meters. Tuning is quite broad on this band because the antenna is
physically much taller than a 1/4-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.

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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.
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 inch 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
described earlier.
NOTE: In above-ground installations it will usually be found that resonance and lowest VSWR
occur at slightly higher frequencies on all bands compared to ground-level installations. Therefore
on 15 and 10 meters, where length adjustment is the means of getting antenna resonance, it is
recommended that the length of the stranded-wire between wire clamp 0.500" 15M with wire (L)
and wire clamp 0.875" 15M with insulator (K) be increased approximately 3 inches and that tube (J)
be extended approximately 6 inches beyond the original dimensions given if any above-ground
installation is contemplated. These are merely recommended preliminary settings, for it is
impossible to indicate precise settings that will produce resonance or lowest VSWR at a given
frequency in all installations. In the preceding steps it has been assumed that the antenna has been
installed in a more or less clear spot away from other vertical conductors such as TV antenna
feedlines, towers and masts, and that a minimal ground system (or a system of resonant radials in
the case of above-ground installations) has been installed. If those fairly basic conditions have not
been met it is likely that resonance and low VSWR will be impossible on some or even all bands.
One should bear in mind that VSWR, even with a resonant antenna, will depend in large measure on
local ground conductivity, height above ground in the case of an elevated antenna, the extent of the
radial, counterpoise or other ground system used, and on other factors over which the operator may
have little or no control. Fortunately, the evils of VSWR greater than unity have been grossly
exaggerated in recent decades, and the only practical difference between a VSWR of unity and one
of, say, 3:1 in the average case lies in the reluctance of modern equipment to deliver full power into
lines operating at the higher VSWR without the help of a transmatch or other outboard matching
device.
Transmitters having so-called broadband solid-state output circuits (no tuning or loading controls)
may be especially troublesome in this regard, whereas the older vacuum tube pi-network
transmitters can usually be adjusted for maximum output over a tuning range where the VSWR does
not exceed 2:l.

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Above Ground (Elevated) Installations
The problem of ground loss resistance may be avoided to some extent by mounting a vertical
antenna some distance above the earth over an artificial ground plane consisting of resonant
(usually 1/4-wave) radial wires. Four resonant radials are considered to provide a very low-loss
ground plane system for vertical antennas at base heights of 1/2-wave or more. This arrangement
contrasts favorably with the more than 100 radials for zero ohms loss resistance at ground level, and
since 1/2-wave is only about thirty-five feet at 20 meters, very worthwhile improvement in vertical
antenna performance can be realized, at least on the higher bands, with moderate pole or tower
heights. At base heights below 1/2-wave more than four radials will be required to provide a ground
plane of significantly greater conductivity than the lossy earth immediately below the antenna: even
so, a slightly elevated vertical with relatively few radials may be more effective than a ground-level
vertical operating over a larger number of radials if only because the former is apt to be more in the
clear. Resonant radial lengths for any band may be calculated from the formula:
Elevated antennas may interact with the coaxial cable and cause RF feedback into the shack. It is
recommended that a Feedline Current Choke be installed at the base of the antenna near the
feedpoint connection.
Figure 1 shows the basic ground plane system for elevated verticals. Radials may
slope downward as much as 45 degrees without any significant effect on operation or
performance. Radials for different bands should be separated as much as possible and
the far end of each radial insulated from supporting wires. Figure 2 shows a ground
plane system that uses four resonant radials for 40 meters, another set of four for 20
meters, and a third set for 10 meters. A separate set for 15 meters is not ordinarily
required because the 40 meter radials operate as resonant 3/4-wave radials on that band. Figure 1
At the lower heights the separate wires of this system may provide enough
capacitance to ground to permit low SWR operation on 80/75 meters as well,
but it is probable that at least one resonant radial will be required for low SWR
on that band. It’s important to note that cutting each conductor to a specific
frequency will not work unless you separate it, angling each conductor away for
most of its length because the longer ones will detune the shorter ones. Figure 2
Above Ground Radial Systems
The 12-radial system of Figure 2 is a very good one, but it requires at least 12 tie-off points.
Butternut®has developed a multiband radial made of 300 ohm twinlead that resonates
simultaneously on 40, 20, 15 and 10 meters. Four such radials offer essentially the same ground
plane performance as the system of Figure 2 but require only 4 supports. These multiband radials
plus additional wire for an 80 meter radial are available separately (BUT-STR-II) or as part of the
Butternut®roof mounting kit (BUT-RMK-II).
There are times when physical restrictions will dictate the use of
fewer than four radials, and at least one manufacturer recommends 2
radials per band, the radials for each band running 180 degrees away
from each other. A simpler (and no doubt less effective) system is
shown in Figure 3. Since only one resonant radial is used per band
the antenna will radiate both vertically and horizontally polarized Figure 3