Diamond Antenna MV3A User manual

MV3A Mobile Antenna System
General Information
MV3A has 4 band capability—2m/6m, plus 2 HF bands though use of loading coils. The MV3A is supplied with HVC28 (10m) loading
coil. There are four optional HF coils available: HVC7 (40m), HVC14 (20m), HVC18 (17m), and HVC21 (15m). The MV3A has a fold-
over structure which allows for entrance into parking structures (i.e. garages, buildings, etc.). Use DIAMOND model MX62M Duplexer
for single antenna operation with ICOM IC-706, Yaesu FT100 or for combining HF & VHF transceivers.
Specifications
Bands Supplied 10m/6m/2m
Power, PEP: HF 120 watts / VHF 200 watts
Mount Connection: UHF
Length: 58” (with the HVC7 installed, total length is 80”)
VSWR: 1.5:1 Nominal–MV3A (10m/6m/2m)
Frequency: 2m: 144.5-148 MHz; 6m: 52-54* MHz;
(Nominal BW) 10m Loading Coil: 28-29 MHz (± 300 Khz)
HVC7 (40m): (± 28 Khz)
HVC14 (20m): (± 60 Khz)
HVC18 (17m): (±140 Khz)
HVC21 (15m): (± 180 Khz)
*6MSSB-EXT (6m SSB) (± 500 Khz)
Element Phasing: 5/8O2m, 1/4O6m
Recommended Antenna Mounts: Diamond K400C or K600M
Recommended Duplexer: Diamond MX62M
Installation Instructions
PRECAUTIONS:
(1) The MV3A requires vehicle ground.
(2) If installing HVC7 (40m) loading coil, install on top (vertical position) only. Some installations may require a nylon
cable to relieve stress on vehicle mount.
(3) The MV3A 6m/2m tuning assumes that at least one loading coil is mounted at the top end. VSWR may be out of
specification without the coil(s).
(1) Choose desired mounting location to insure maxi-
mum strength of mount, best performance of antenna, and
proper vehicle ground.
(2) Assemble MV3A with desired loading coil (HVC28
10m coil is included in package) and install on vehicle mount.
NOTE: Metric Hex wrenches are enclosed.
(3) With quality VSWR meter, check VSWR on all bands
to insure proper tuning of antenna. The loading coil rods
may require adjusting or trimming to reach best VSWR. If
it is necessary to trim coil rods, do so in 1/8” increments
only, until lowest VSWR is obtained at desired center fre-
quency. Shortening coil rods will have the effect of raising
the resonant frequency. Check both the high and low band-
width edges before cutting.
—10m Coil
MV3A Parts List
Discharge Protection Cap
Trim element with cutting de-
vice appropriate for cutting
metal. (i.e. Hacksaw, etc.)
Metric Hex Wrench M4

(4) When tuning optional loading coils (HVC7, HVC14, HVC18,
HVC21 and HVC28-10m coil), install on the top (vertical position) and
proceed to tune the coils by adjusting or trimming coil rods. (NOTE: HVC
Tuning Coils have a limited tuning range–refer to “frequency” under speci-
fications for bandwidth). Choose your desired center frequency as a guide
for tuning range and adjust for best VSWR at center frequency.
(5) Once you have adjusted all coils for best VSWR in the vertical posi-
tion, you may assemble one optional coil horizontally. All coils can work
horizontally except the HVC7 (40m); it must be in the vertical position due
to its size. The VSWR will change slightly by adding a coil horizontal; there-
fore, it is best to check your VSWR readings to verify tuning.
(6) To replace loading coils, simply unscrew coil from coil support
bracket and replace with another coil (see illustration). Be sure loading
coils are fastened securely so they don't loosen from vehicle and road
vibration.
(7) The MV3A has a fold-over structure for situations where the
antenna height is a problem (see illustration). Simply unscrew the
fold-over lock, lift up, and tilt over 90°. Care should be taken when
folding over, not to damage vehicle or any loading coils. Do not
drive with antenna in the folded position.
MX62M Duplexer
LPF 1.6-56; HPF 76-470
Power; 200w CW, 600w PEP
Connectors: Mix-UHF(F);
Ports-UHF(M)
w/12” cable
K400C
Trunk/Hatchback Mount
Deluxe UHF type base
Dual-axis adjustable
6½” RG316 Teflon Coax
w/PL-259.
Use Diamond Model C110
for front radio installations.
K600M
Trunk Mount
Deluxe trunk mount.
16.5' RG188 and 7mm 5D Coax.
Tilt Angle (0-9°)
MV3A Accessory Items
— 40m
—20m
—17m —15m
—10m
HVC Loading Coils

HF Mobile Installation Tips
With all the different types of installations possible, there are many unique problems that can occur. We have compiled some additional
notes on specified areas.
(1) GROUNDING ANTENNA: Obtaining a good ground is very important to any HF mobile installation. No matter where your
antenna is mounted, it is highly recommended your run a heavy copper strap or braid (1” to 3”) between body and frame of your vehicle.
(NOTE: Copper wire is not sufficient!) If you have ignition noise problems, it is also recommended to ground the end of your tail pipe to
the frame.1
(2) OPTIMUM MOUNTING LOCATION: You should always mount your antenna as high on your vehicle and as far away
horizontally from other metal objects as possible. The center of your roof is the best location; however, this is not always practical or
possible for most HF antenna installations. The next best location is in the center of the driver's side of the trunk (side mounted on driver
side to avoid low hanging curbside branches or objects). The DIAMOND K400C and K600M series mounts work well with the MV3A.
The front or rear bumper is another possible mounting location; however, due to high ground loss, this should be last choice. If you must
use a bumper mount, it is recommended to use a base extension to raise bottom of antenna to equal height of top of trunk. Grounding of
this extension will become important.
(3) TRUNK LID MOUNTING: Probably the best mounting location for most vehicles. Usually, adding one or two copper straps
from the hinge area to car body will improve grounding (and thereby antenna tuning). It is necessary that at least two of the four
sockethead screws on mount penetrate paint to metal for proper grounding. (A little clear nail polish or other acrylic paint may be used
to seal around mounting screws.)
(4) COAX: If you use an antenna mount other than DIAMOND ANTENNA models K400C or K600M, it is very important to use
a quality 52 ohm coax (RG8U, RG58U, RG213, Teflon Coax, etc. with at least 95% shield and stranded center conductor). Do not use
foam coax or coaxes with solid center conductors. Foam coax can deform in heat and absorb moisture, solid center conductor coaxes
have less flexibility and may become brittle and break in mobile applications.
(5) EMI: Electromagnetic Interference is the single greatest concern for HF mobile applications. Route your cable as far from the
vehicles ECM (Engine Control Module) and vehicle's electrical systems as possible. Sometimes a ferrite choke may be required on coax
near mount. There are many books on the subject of interference, refer to endnotes for additional information.2
1. J. Seybold, “HF Mobile Installation Tips”, December 1995 QST, pg. 58-60.
2. ARRL, Radio Frequency Interference Tips: How to find it and fix it., The book is available from your favorite amateur radio dealer
or ARRL headquarters.
Diamond Antennas and Meters are distributed by
RF Parts Company•435 S. Pacific Street•San Marcos, CA 92078 •[phone]

VSWR Charts
HVC7
HVC14 HVC18
HVC21 HVC28
WARNINGS:
(1) Bolts and set screws on antenna and mounting bracket may
loosen from vehicle and vibration. Be sure to check periodically to
ensure they are fastened securely.
(2) Avoid obstacles such as tree branches or low overpasses;
impact with these obstacles will cause antenna to break.
(3) The MV3A is not recommended for either magnet type mounts
or installation on large GVW vehicles.
(4) Avoid touching antenna while transmitting.
(5) Do not scratch or remove rubber covering on loading coil
sections.
(6) Avoid driving with antenna in folded position.
6MSSB-EXT
SSB extension rod for MV3A
The 6MSSB-EXT lowers the 6m resonant frequency of MV3A for 50.1 operation.
NOTE: With 6MSSB-EXT installed, you will lose 2m capability of MV3A.
Installation: (You have two installation options.)
(1) If using one HF coil, simply install in horizontal loading coil support bracket #67402. Follow tuning
instructions below.
(2) If using two HF coils, remove set screw #67403 from horizontal loading coil support bracket #67402. Attach
6MSSB-EXT and fasten lock nut. Follow tuning instructions below.
Tuning Instructions: With quality VSWR meter, check VSWR on lower portion of 6M (approx. 50.125 MHz). The
extension rod may require adjusting or trimming to reach best VSWR. If trimming is required, do so in 1/8” increments
only, until lowest VSWR is obtained. Shorting extension rod will have the effect of raising the resonant frequency.
Check both the high and low bandwidth edges before cutting.