Hy-Gain AV-680 User manual

308 Industrial Park Road
Starkville, MS 39759 USA
Ph:[phone] Fax: [phone]
INSTRUCTION MANUAL
Made in USA
MODEL AV-680
925-0680-REV A2

Hy-Gain is proud to deliver the AV-680 Nine Band Vertical. Drawing on our many years
of Amateur Radio HF and VHF antenna design experience, we have produced a well-
engineered antenna capable of maximum efficiency, unmatched performance, and
superior construction.
Computer optimization of the AV-680 design yields the most efficient 3/8 wavelength
electrical design with maximum gain and low angle of radiation for long distance
communication. No traps are used to achieve nine band performance. The AV-680 is
resonant on 6, 10, 12, 15 and 17 meters with individual 3/8 wavelength radiators. The
center radiator resonates on 20, 30, 40 and 80 meters using parallel end loaded Teflon
wire coils. Capacity hats on these bands give wide 2:1 VSWR bandwidth and the antenna
is kept to a height of 27 feet by the low inductance coils. There are no "tricks" or
"mystery resonances" used for impedance matching on any band.
No long-wire radials or counterpoise kits are necessary for operation of the AV680.
The AV-680 is self contained for simple, convenient portable or fixed operation.
Mechanical construction of the AV-680 is designed for extreme light weight and high
wind survival. Aircraft grade 6063-T832 aluminum and high strength fiberglass are used
for the entire radiator. The trap-free design presents a very low wind surface area. Bulky
tubing is not required to support unwieldy traps. The broad 2:1 VSWR bandwidth on all
bands lessens large frequency shifts seen in other antennas when the antenna is wet or
iced.
The AV-680 is covered by our Hy-Gain Warranty and supported by our customer service
team. We would like to thank you for purchasing this product from us and ask that you let
us know of any suggestion you may have. With proper assembly, installation, and
maintenance, your AV-680 will provide years of faithful service.
The AV-680 HF Multiband Vertical antenna consists of an end fed radiator that is
resonant in the 6, 10, 12, 15, 17, 20, 30, 40 and 80 meter amateur frequency
bands. Resonances on each band are the result of impedance matching a 3/8
wavelength element with a broadband RF transformer. The characteristic
impedance at the base of the 3/8 wavelength radiator is in the order of a few
hundred ohms.
To match this impedance two tools are employed. First a counterpoise of 72"
spokes is mounted at the AV-680 base. The capacitance from this ground plane
Introduction
Theory of Operation
2

helps lower the base impedance. Second, a 4:1 toroidal transformer (voltage balun)
steps the base impedance down to 50 ohms. This transformer uses a ferrite core for
high power capability. Also, the windings are made of twisted pair wire to improve
coupling and reduce loss. A second high power transformer is configured as a 1:1
current balun to help stop RF from traveling back on the feedline shield. The radiator
of the AV-680 is at DC ground potential for static drain. This is accomplished by a
radio frequency choke in the matching circuit.
The center radiator of the AV-680 supports 1/4 wavelength stubs for 6 , 10, 12 and 17
meters. The stubs are placed approximately one tenth of a wavelength (electrically 1/8
wavelength) above the AV-680 base. At the top of each stub the impedance is very high
at the frequency the stub is tuned. This high impedance stops, (chokes) RF at this point
creating a resonant 3/8 wavelength radiator. There is minimal loss using this method as
compared to standard trap circuits. Also, VSWR bandwidth is not restricted by the °Q"
of trap components. For 20, 30, 40 and 80 meters, a coil and capacity hat are used on
each band to create a 3/8 wavelength radiator. The coils are mounted at the top of the
center radiator. These foer coils are connected in parallel. Parallel connection separates
each band to allow individual band tuning and has less loss than does series connection.
Also, the AV-680 coils have significantly less loss than a standard trap because the AV-
680 capacity hats exhibit greater capacitance than a typical trap, therefore, less
inductance is required.
Antenna Location
The best performance for receiving and transmitting will be obtained by mounting the
antenna in a clear location above or away from buildings, buildings, towers, feedlines,
utility wires, and other antennas. While your own ingenuity and particular circumstances
will determine the final mounting method, remember, any object within 75 feet from the
base of the antenna can influence the performance of the AV-680.
WARNING: Always mount this antenna so that it is out of the reach
of adults as well as children and pets. The counterpoise rods can
cause injury and or severe RF burns.
·NEVER mount this antenna in a location that will permit
unsuspecting people to come in contact with any part of the
antenna.
·NEVER mount this antenna where a mechanical failure might
allow the antenna, antenna support or feedline to contact power
lines or other utility wires.
·ALWAYS ground the feedline at the point where it enters a
building to a good earth ground for lightning protection.
·ALWAYS follow the guidelines for antenna installations as
recommended by the US Consumer Product Safety Commission.
3

Antenna Mast
The recommended support mast for the AV-680 is steel water pipe between the sizes of
1-3/4" OD to 2 1/2" OD and with a length that will place the antenna base at a safe
height. Do not use thin walled conduit, aluminum tubing, or "TV" mast. The AV-680
is designed to operate at a height of 8 or more feet for proper performance. Placement
on the side of a house or garage at eaves level is acceptable as long as the counterpoise
whips will not be in contact any snow on the roof. Placement above metal roofs is
acceptable if the antenna base is at least 5 feet or more above the metal surface.
Antenna Grounding
Although the AV-680 is designed to operate efficiently without the requirement of an
earth ground, SAFETY GROUNDING must still be provided to protect equipment,
property and persons from the hazards of lightning strikes and other weather related
electrical discharges. In addition the coaxial cable feeding the antenna should have the
shield grounded to eliminate the risk of any indoor equipment failure from allowing
hazardous voltages from appearing indoors and creating a shock hazard. The support
mast should be grounded with a large diameter ground wire.
The AV-680 is DC grounded for static discharge. This is accomplished with a choke
coil in the Matching Unit. This coil could fail under high voltage spikes from a near or
direct lightning strike.
Additional protection can be accomplished by grounding the shield of the coax where
it enters the building to a good earth ground or directly burying the cable in the earth
for several feet before it enters the building. The coaxial cable should be totally
disconnected from the station during threatening weather conditions for maximum
lightning protection.
Antenna Guying
For normal operation up to 65 mph winds, the AV-680 will not require guying. For
extreme locations such as tall building rooftops, a safety guy is recommended. Use
Dacron® rope to guy the center radiator. Attach ropes 14 feet above the antenna
base. Use care not to disturb the radiator stubs.
Customer Supplied Components
•Quality low-loss 50 ohm coax cable with PL-259 connectors
•VSWR Analyzer (MFJ-259B or equiv.) or HF transceiver with VSWR
meter
.Mounting mast with required hardware to provide sturdy support
4

Tools Required For Assembly
•1/4" Standard Blade Screwdriver •7/16" Nut Driver
•#1 Phillips Screwdriver •7/16" Open End Wrench
#2 Phillips Screwdriver •10 nun Open End Wrench
3/8" Open End Wrench •Tape Measure 20'
3/8" Nut Driver •Safety Glasses
5/16" Nut Driver •Pliers
5/16" Open End Wrench
Safety Precautions
WARNING: You can be killed if the antennas, feedline, or the
equipment used to install the antenna accidentally contacts any utility
lines. Never install an antenna near power lines!
·Be careful while climbing and carrying the antenna. It is heavy
enough to cause you to lose your balance if it is handled too casually
or if any part of the antenna snags on a gutter, ladder, tree, or other
item.
·Mount the antenna high enough and in the clear so that it is out of
reach by any person or pet. Do not allow trees or other structures
near the radiator portion of the antenna. The counterpoise whips can
cause serious eye injury.
·Ensure that the mast is sturdy enough to support the weight of this
antenna including the windload of the antenna.
5

Parts List
Part Number Part Description ID Number Quantity
17-AV680-4 Instruction Manual Bag IM 1
17-AV640-1 Parts Bag #1 PB1 1
17-AV640-2 Parts Bag #2 PB2 1
17-AV640-3 Parts Bag #3 PB3 1
80-AV680-1 AV680 Matching Unit MU 1
810-0620-1 Base Insulator 1-1/4" x 12" IN 1
11-0680-1 AV-680 Coil Assembly L1 1
810-0640-5 Base Tube 1-1/2" x 12" BA 1
810-0640-2 Radiator Section 1-1/2" x 72" BB 1
810-0640-3 Radiator Section 1-3/8" x 75" BC 1
810-0640-4 Radiator Section 1-1/4" x 75" BD I
810-0640-9 Radiator Section 5/8" x 36" BF 1
17-AV680-9 Small Tube Bundle ST 1
17-AV680-10 Spoke Bundle BS 1
735-0680 Antenna Mounting Plate MB 1
Small Tube Bundle 17-AV680-9
Part Number Part Description ID Number Quantity
810-0680-55P Stub Section 3/8" x 55" E1 4
810-0680-60 Stub Section 3/8" x 60" E2 2
810-0680-44 Stub Section 3/8" x 44" E3 2
810-0680-6 Stub Section 5/16" x 6" Rod CP 8
758-2764 72" Stainless Steel Whip CW 7
Spoke Bundle 17-AV680-10
810-0680-48 1/8" 48" Aluminum Rod SP1 8
810-0680-36 1/8" 36" Aluminum Rod SP2 4
810-0680-25 1/8" 25" Aluminum Rod SP3 4
810-0680-15 1/8" 15" Aluminum Rod SP4 4
810-0640-28 1/8" 40" Aluminum Rod Spares 2
810-AV640-23 Radiator Section 3/4 x 22”BE 1
6

Part Number Part Description ID Number Quantity
925-AV680 AV-680 Instruction Manual MN 1
925-0006 Hy-Gain Warrant Card WC 1
784-1780 Warning Label WL 7
Parts Bag #1 Part Description ID Number Quantity
656-0375S 6-32 x 3/8" Screw SS S1 48
656-0500S 6-32 x 1/2" Screw SS S2 12
656-1250S 6-32 x 1-1/4" Screw SS S4 12
656-1500S 6-32 x 1-1/2" Screw SS S3 6
656-1750S 6-32 x 1-3/4" Screw SS S5 2
705-0632S-K 6-32 Nut W/Lock SS N1 82
660-0375S 10-32 x 3/8" Screw SS S6 12
711-1037S #10 Lock Washer SS W1 8
745-3104S #4 Hose Clamp SS 12
705-1032S-NL 10-32 Nut Nylon Insert SS N3 8
662-2000S 1/4-20 x 2" Bolt SS S8 4
705-2520S-NL 1/4-20 Nut Nylon Insert SS N5 8
745-3110S 1" Hose Clam SS HC2 1
745-3112S 1 1/2" Hose Clam SS HC1 3
765-1002 1/8”Rod Cap
745-3108 Counterpoise Ring SS W/tabs RI 2
745-3116S #16 Hose Clamp SS 3
765-1062 Plastic Ca 5/8" C2 1
Part Bag #3 Part Description ID Number Quantity
735-1618 Single Stub Base Bracket SB1 2
735-1611 Dual Stub Base Bracket SB2 1
738-0680-3 Single Stub Insulator P3 5
738-0680-1 90 Degree Stub Insulator P1 2
738-0680-2 180 Degree Stub Insulator P2 2
11-AV620-1 Jumper Wire J1 1
Parts Bag #2 Part Description ID Number Quantity
735-1610 Radiator Clamp Bracket RB 16
195902 Mast Saddle 2
170035 AL mast block 2
4
555747 5/16 x 18 nut
4
564792 5/16 split washer
2
543792 5/16 u-bolt
4
555694 3/8 x 16 nut
4
561016 3/8 split washer
2
013209 3/8 u-bolt
SB2
SB1
SW1
NB1
UB1
UB2
SW2
NB2
17-AV680-4
17-AV680-1
17-AV680-2
17-AV680-3

Plastic parts
Aluminum parts
90 Degree Stub Insulator
P/N 738-0680-1 Qty (2)
ID # P1
180 Degree Stub Insulator
P/N 738-0680-2 Qty (2)
ID # P2
Single Stub Insulator
P/N 738-0680-3 Qty (5)
ID # P3
Single Stub Base Bracket
P/N 735-1618 Qty (2)
ID # Sb1
Radiator Clamp Bracket
P/N 735-1610 Qty (16)
ID # RB
Dual Stub Base Bracket
P/N 735-1611 Qty (1)
ID # Sb2
8

TASK I
Center Radiator Assembly
( ) Refer to Figure A to assemble the Center Radiator. Attach BA tubing section to either
end of the Base Insulator (IN) with (2) 1/4-20 x 2" bolts (S8) and (2) 1/4-20 nylock nuts
(N5). Do not tighten the nuts at this time.
( ) Find the (2) counterpoise rings (RI) The ones with the tabs. . Press the flat sides of the
rings together and slide them onto the Base Insulator (IN). Leave rings loose at this time.
( ) Attach the drilled end of tubing section BB to the Base Insulator (IN) with (2) 1/4-20
x 2" bolts (S8) and (2) 1/4-20 nylock nuts (NS). Do not tighten the nuts at this time.
( ) Place (1) hose clamp (HC 1) over the slotted end of tubing section BB. Slide unslotted
end of BC tubing section into BB until it stops. Tighten hose clamp. NOTE: For
protection against oxidation, a conductive paste such as NoAlox® may be used between
telescoping pieces of aluminum tubing only. Do not apply the paste to insulators or coax
connections.
( ) Place (1) hose clamp (HC 1) over the slotted end of tubing section BC. Slide unslotted
end of BD tubing section into BC. Tighten hose clamp.
( ) Place (1) hose clamp (HC 1) over the slotted end of tubing section BD. Insert AV-680
Coil Assembly (LI) 4 inches into tubing section BD. Tighten hose clamp.
( ) Install two sections BE and BF on top of the coil assembly. Use the 6-32 x 1- ¼
screw and nut to secure BE into the top of the coil assembly. Slide BF into BE three
inches and place the HC2 hose clamp over the slotted end and tighten. Install the
jumper on the top of the loading coil to the tube BE using a 6-32 x 1-1/4”screw and nut.
( ) Place 5/8" plastic cap (C2) on end of tubing section BF
TASK II
Stub Base Bracket Assembly
( ) Refer to Figure B for Stub Base Bracket Assembly. Study Figures B and C to learn
how the stub base brackets are attached for each band. Note how the brackets are offset
90 degrees from each other for proper antenna assembly.
( ) Find the aluminum Stub Brackets (SB 1 & SB2). Attach a Radiator Bracket (RB) to
each Stub Bracket with (2) 6-32 x 3/8" screws (S I) and (2) 6-32 lock nuts (N1) as shown
in Figure B.
( ) Find a Single Stub insulator (P3). Attach it to a Radiator Bracket (RB) with (2) 6-32 x
3/8" screws (S I) and (2) 6-32 lock nuts (NI).
9

( ) Mount each Stub Base Bracket to the AV-680 Radiator using a Radiator Bracket
(RB), (2) 6-32 x 1 1/2" screws (S3), and (2) 6-32 lock nuts (N1). Place the Single Stub
insulator opposite the Single Stub Base Bracket shown in Figure C.
( ) NOTE the degrees offset for each bracket and the distance from the base insulator
(IN) in Figure C. Position the Stub Brackets ABOVE the Radiator Brackets.
TASK III
Stub Insulator Assembly
( ) Place the AV-680 Radiator on a flat surface such as a driveway or garage floor. This
will aid in mounting the Stub Insulators by keeping them aligned with each other.
( ) Refer to Figure D for Stub Insulator Assembly. There are three types of stub
insulators: Single, 90 Degree and 180 Degree. The 180 Degree insulators are used with a
Single Stub insulator to make a Three Stub insulator. The locations of the Single
insulators are labeled «A", 90 Degree insulators are labeled "B" and the Three Stub
insulators are labeled "C".
( ) Attach 90 Degree Stub Insulators (P1) to a Radiator Bracket (RB) using (2) 6-32 x
3/8" screws (S1) and (2) 6-32 Keps nuts (N1) as shown in Figure D.
( ) Attach Single Stub Insulators (P3) to a Radiator Bracket (RB) using (2) 6-32 x 3/8"
screws (S l) and (2) 6-32 Keps nuts (NI).
( ) For Three Stub Insulators, attach a Single Stub and a 180 Degree Stub Insulator (P3
& P2) to a Radiator Bracket (RB) using (2) 6-32 x 1/2" screws (S2) and (2) 6-32 Keps
nuts (N1).
( ) Mount the Stub Insulators on the AV-680 Radiator using a Radiator Bracket (RB), (2)
6-32 x 1 1/4" (S4) screws, and (2) 6-32 Keps nuts (N1). USE the dimensions in Figure E
to space and rotate the insulators into their proper locations. Position the Stub Insulators
ABOVE the Radiator Brackets.
TASK IV
Stub Assembly
( ) Refer to Figure F for the stub assembly diagram.
Assemble the stubs on the antenna.
( ) All four stubs share the same base tube ( E1 ) which has the threaded insert in one
end. This end attaches to one of the metal brackets at the bottom of the antenna. You
may attach all four of these elements sections to the antenna using the 10-32 screw and
lock washer. Use “Figure G”For location of each Stub.
10

( ) SIX METER STUB: The six meter stub consist of only the first section (E1) and
the coupler (CP) and is attached to the lowest metal clamp on the antenna “Figure C”
Slide the coupler into the top of the stub and use a hose clamp to secure it. This rod will
be used to adjust the length of the stub.
TEN AND TWELVE METER STUB:
( ) TEN AND TWELVE METER STUB. These two stubs are attached to the 180
degree metal bracket above the 6 meter stub “Figure C”. It does not matter which side
you chose for each band. They will work the same in either place. Assemble them on the
antenna by sliding the sections down the insulators and connecting them using the
couplers (CP) and the small hose clamps. The 10 meter uses the E1, and E3 sections
which makes it slightly shorter than the 12 meter section which uses E1 and E2. Insert a
coupler into the top of each section and secure it with a hose clamp.
( ) SEVENTEEN METER STUB: This is the longest stub and consist of all three
sections E1,E2 and E3. This element attaches to the uppermost metal bracket and
extends all the way up to the loading section of the antenna. Insert each section into the
insulators and connect them using the couplers (CP) and hose clamps. Insert one coupler
into the top section and secure with the hose clamp.
11

TASK VI
Matching Unit Mounting
( ) Refer to Figure H for the mounting location of the Matching Unit (MU). Use the
pair of bolts through the Base Insulator (IN) to mount the MU as shown in Figure H.
Remove the (2) 1/4-20 nuts (N5) from the (2) 1/4-20 x 2" bolts (S8) previously
installed.
( ) Place the Matching Unit on the bolts and secure in place with the (2) nuts. Be sure the
coax connector end of the Matching Unit faces the base (bottom) of the antenna.
( ) Using a 6-32 Keps nut (N1), connect one end of the jumper wire (JI) to the
counterpoise terminal of the Matching Unit. Do not over-tighten this nut. The other end of
the jumper wire is attached later.
TASK VII
Counterpoise Assembly
( ) Refer to Figure H to assemble the counterpoise.
( ) Loosely attach the counterpoise rings (RI) to the base insulator (IN) with (2) 6-32 x 1
3/4" screws (S5) and (2) 6-32 Keps nuts (NI).
( ) Loosely attach the counterpoise rings (RI) together with (8) 10-32 x 3/8" screws (S6)
and 10-32 nylock nuts (N3).
( ) Place the (7) 72 inch (183 cm) counterpoise whips (CW) into the slots provided in the
sides of the rings. The slot facing the Matching Unit (MU) does not receive a whip.
( ) Tighten the 10-32 nuts (N3) around the rings to secure the whips.
( ) Place the loose end of jumper wire (Jl) under the closest 6-32 screw (S5) that holds a
ring to the base insulator as shown in Figure H. Tighten the (2) 6-32 nuts (N l) that secure
the rings to the base insulator.
( ) Attach a warning label to the end of each whip as shown in Figure H.
TASK VIII
Antenna Mounting Plate Assembly
( ) Refer to Figure I for assembly of the Antenna Mounting Plate (AM).
( ) Attach the antenna to the mounting plate first as the u-bolt nuts will not be accessible
onec the mast is attached. Place a drop of oil on the threads of each u-bolt to prevent
stainless components from seizing together.
12

( ) The smaller u-bolt should be on top and center between the two ¼-20 bolts in the
mast. If the lower bolt contacts the bracket then rotate it around the mast until it clears.
( ) Tighten the (4) bolts that hold the antenna to the bracket.
( ) Place the (2) Larger U-bolt assemblies into the holes in the antenna mounting plate
as shown in Figure I. Leave nuts loose until installation of the antenna.
TASK IX
Capacity Hat Assembly
( ) Refer to Figure J for assembly of the five Capacity Hats.
( ) Rotate the AV680 Coil Assembly (Ll) so the top end of the 17 meter stub is away
from the AV680 Coil Strap as shown in Figure J. To rotate the coil assembly, loosen
the lower coil hose clamp (HC 1). Tighten hose clamp when finished.
( ) Place (8) 6-32 x 3/8" screws (S1) and (8) 6-32 lock nuts (Ni) in each Counterpoise
Ring assembly on the AV-680 Coil Assembly (LI). Leave the nuts loose so that the
spokes can be slid between the rings.
( ) There are spokes of lengths 15", 25",36" and 48". Place the spokes in the ring
assemblies as shown in Figure J. The shorter spokes will be on the bottom end of the
coil and the longer spokes will be on the upper end of the coil. The 40" spokes are
spares. Tighten all hardware on the ring assemblies. Slide the 1/8 inch rod caps onto
each of the rods. Use caution when around the spokes, they will poke you easily.
( ) NOTE: For tuning 20, 30, 40, and 80 meters, the lengths of the spokes are adjusted as
shown in Figure J. It is suggested that the spokes be installed at their initial lengths. If
any of the bands are resonant too low in frequency, one of the corresponding spokes can
be pruned. Only one spoke will r equire pruning but you may also pr une the one on the
opposite side to maintain a balanced look to the spokes. Please refer to the Tuning section
in figure J for more information.
Installation
The AV-680 antenna should be mounted at least 8 feet above ground. The main reason for
this minimum height is safety. The AV-680 will work well at a minimum height of five
feet but precautions from dangerous voltages must be taken.
Always have help for the installation process. Do not attempt to install the antenna
alone. Review the requirements for Antenna Location and safety precautions regarding
Power Lines earlier in this manual.
13

The AV-680 may be roof mounted on a tripod or similar support. Keep the AV-680 base
a minimum of 5 feet above the roof surface. This minimum dimension is the same for
any roof material type. Attach a suitable ground wire to the support mast as mentioned
in the Grounding section of this manual.
Tuning
The 2:1 VSWR Bandwidth should be referenced to determine performance. VSWR
measurements made at the antenna base are the most accurate and may show a
slightly narrower VSWR bandwidth than the specifications chart lists. Be sure to use
very low power (less than 5 watts) when measuring VSWR at the antenna base.
The AV-680 should be checked with an VSWR meter before permanent installation to
verify proper assembly and Matching Unit performance. Place the AV-680 at least 8 feet
above ground and in as clear an area as possible. Connect the coax to the antenna base and
test the VSWR using either an MFJ-259B VSWR Analyzer or equivalent or a transceiver
and VSWR meter.
Tuning 20, 30 and 40 meters
Individual adjustment of 20, 30, and 40 meters is accomplished by pruning one spoke in
the corresponding capacity hat. Only one spoke needs to be adjusted and it does not
matter which spoke is selected. Refer to Chart B to calculate the amount of spoke to
prune and Figure J for spoke location. It is strongly suggested the AV-680 be assembled
and tested with the spokes at the initial lengths to determine if any pruning is actually
required. The initial length will tune the antenna to a frequency below each band.
Trimming the spokes will cause the resonant frequency to go up. Trim a small amount
each time and recheck. If you go too far and the resonant frequency is too high, make a
longer spoke from one of the 40" spare spokes and try again.
Tuning 80 meters
80 meters has an additional tapped loading coil that will allow for retuning the antenna
after the spokes have been adjusted. For initial tuning, move the tap to the uppermost
part of the coil so that all the turns are shorted out. Trim the spokes for the top of the
band. Use the tapped loading coil to lower the operating frequency by moving the tap
down. Set the antenna to the frequency you will be using the most. Use a Phillips
screwdriver to secure the tap to the coil.
Tuning 6, 10, 12, 15 and 17 meters
Stub lengths can be adjusted for tuning the 6, 10, 12 & 17 meter bands. 15 meters
usually will not require adjustment but can be adjusted by moving the loading coil on the
main mast in and out of the main radiator. The total stub lengths are found in figure F.
These values will tune the antenna to the lower part of the band.
The AV-680 has few variables in its design. Therefore, VSWR should be very close
to specifications. Each band can be adjusted individually. The element and stub
lengths given in the drawings for the assembly of the antenna should tune the antenna
close to the bottom of each band. Adjusting the stub lengths and trimming the
capacity hats for each band will be needed to set the antenna your preferred section of
the band.
14

Please note the length of coax will vary the VSWR on certain bands. Lengths less than 50
feet have stronger harmonic resonances than longer lengths. If a particular band will not
properly resonate, try adding 3-5 feet or more of coax. Record the resonant frequencies
with and without the added coax. There will be a change in resonant frequencies on one or
more bands. RF loss at HF is not a major problem with RG8X or larger coax. There will
be a minimal performance difference between a 50 ft. length and a 75 ft. length of coax.
To lessen the possibility of RFI/TVI, roll up 6-8 turns of coax 8" inches diameter
approximately one quarter wave (or multiple) from the base of the antenna. Use the
quarter wave length of the frequency that causes the greatest amount of
interference.
Maintenance
The AV-680 should be inspected mechanically at least once a year. Normal wear and tear
varies significantly with climate.
Anti-Oxidation paste such as NoAIOX® or others can be applied to the radiator tubing
sections. Use small amounts. Do not place the paste on the coax connector or inside of the
Matching Unit.
Inspect the inside of the Matching Unit on a regular basis. Remove dirt, bugs, or
questionable material. Look for any degradation of parts. High voltage static
discharges (lightning) may cause a failure to the small coil in the Matching Unit. This
coil is a protection device. Make sure it is in good shape.
Do not screw and unscrew the nylon insert nuts several times. If portable operation
is desired, use stainless steel hardware without the nylon locking feature.
Tec hnica l A ssista nce
Technical assistance is available during normal business hours on weekdays. Hy-Gain
is located in the Central Time Zone. Our hours are 8:00 AM till 4:00 PM CST Monday
through Friday.
Hy-Gain Telephone [phone]
308 Industrial Park Road FAX [phone]
Starkville, MS 39759 email "hy-gain@hy-gain. com"
Web Page "http://www.hygain.com
15

Service history has shown that most problems are operating or installation errors, rather than
equipment failures. Most problems can be resolved over the telephone. Please contact our
staff before shipping parts or equipment to us.
The packing material used to ship this antenna is designed to prevent shipping damage.
Please reuse the original shipping carton if possible. Hy-Gain will not be responsible for
shipping damage on returned items with improper packing.
BAND
80 Meters
40 Meters
30 Meters
20 Meters
17 Meters
15 Meters
12 Meters
10 Meters
6 Meters 300 KHz per ½ inch
100 KHz per ½ inch
150 KHz per ½ inch
100 KHz per inch
60 KHz per ½ inch
100 KHz per inch
50 KHz per inch
17 KHz per inch
10 KHz per inch
CHART B
Spoke Tuning
Trimming Affect
16

BA
IN
BB
BC
BD
AV-680 L1
1-1/2 X 72 1-3/8 X 69 EXPOSED LENGTH 1-1/48 X 69 EXPOSED LENGTH
BE
C2
1-1/2 X 12
INSERT 3 INCHES
Mount ring before tubing
S8,N5
4 places
FIGURE A
AV-680 Center Radiator Assembly
BF
Connect jumper to tube
17

S1
SB1
RB
N1
Antenna Base
S3
BB
RB
N1
SB1
A
6 Meter Stub
Base Bracket
S1
N1
RB
SB2
B
10&12 Meter
Stub Base
Bracket
Antenna Base
S3
BB
RB
N1
SB1
S1
SB1
RB
N1
S1
P3
RB
N1
BLACK
PLASTIC
ALUMINUM
SB1
P3
C
17 Meter Stub Base
Bracket and 6 Meter
Stub Insulator
SB2
RB
N1
S3
Antenna Base
FIGURE B
Assembly of Stub Base Brackets
18

BA
35”
47”
56”
90 degree offset
on this bracket
6 Meter Stub
Base Bracket
A
10&12 Meter
Stub Base
Bracket
17 Meter Stub Base
Bracket and 6 Meter
Stub Insulator
B
C
FIGURE C
Installation of Stub Base Brackets
19

N1
S3
Antenna Base
S1
N1
S1
P3
RB
N1
Antenna Base
S3
BB
RB
N1
P3
F
Single Stub
Insulator
P2
N1
S1
P3
RB
Antenna Base
N1
S3
E
Three Stub
Insulator
D
90 Degree Stub
Insulator
FIGURE D
Installation of Stub Insulators
20