M2 Antenna Systems 2M4 User manual
M2 Antenna Systems, Inc. 4402 N. Selland Ave. Fresno, CA 93722
Tel: (559) 432-8873 Fax: (559) 432-3059 Web: www.m2inc.com
©2015 M2 Antenna Systems Incoporated 05/26/15
Rev.01
Model .........................................2M4
Frequency Range.......................144 To 148 MHz
*Gain ..........................................9.6 dBi
Front to back ..............................20 dB Typical
Beamwidth ...............................E=54° H=74°
Feed type ...................................“T” Match
Feed Impedance. .......................50 Ohms Unbalanced
Maximum VSWR........................1.5:1
Input Connector..........................“N” Female
Power Handling ..........................2.5 kW
Boom Length / Dia......................48” / 1”
Maximum Element Length..........40-1/2”
Turning Radius: ..........................55”
Stacking Distance.......................66” High & 80” Wide
Mast Size....................................1-1/2” to 2” Nom.
Wind area / Survival ...................0.50 Sq. Ft. / 100 MPH
Weight / Ship Wt.........................3 Lbs. / 4 Lbs.
M2 Antenna Systems, Inc.
Model No: 2M4
FEATURES:
Clean mechanical design, full band coverage and computer optimized performance make the 2M4 an exceptional
antenna. A totally sealed and grounded driven element design with a unique internal balun provides the heart that will
beat for years to come. It is perfect for base and portable use, with FM, Packet or SSB. Every station needs one!!!
SPECIFICATIONS:
*Subtract 2.14 from dBi for dBd
Tools handy for assembly process: screwdriver, 11/32” spin-tite or socket, 7/16” and 1/2” end wrenches /
sockets, measuring tape.
1. Lay out the elements by length and position as shown the DIMENSION sheet. Start with the
REFLECTOR (longest) element. Balance on finger to find rough center and push on a black button
insulator to about 1/2” from center. Push the element through the holes 10" from the rear of the boom
and install the second button, snugging it up into boom. DO NOT BOTHER WITH ACCURATELY
CENTERING the element at this time and DO NOT INSTALL the stainless steel SHAFT RETAINERS
yet. This is easier to do after all the elements are installed in the boom. Install the 3/16” rod DRIVEN
ELEMENT as you did the reflector and then the DIRECTORS.
2. Now accurately center the elements. Use a tape measure to EQUALIZE the amount the element
sticking out on each side of the boom. Begin installing the stainless SHAFT RETAINERS.” Use thumb
and index finger to hold a retainer over end of the 3/8 x 3” push tube (retainer dished into tube). Hold
the element firmly and start the retainer onto the rod by applying pressure with the push tube. Push
the retainer until up tight against the button insulator (Locking pliers, lightly clamped up against
opposite button insulator will help maintain center reference and keep you from pushing the first
retainer too far). Repeat for the opposite side. Continue installing retainers until all elements are
locked in place.
3. Mount the “T” MATCH BLOCK ASSEMBLY to the top of the boom using a single 8-32 X 1-1/4" screw.
Orient the block with feed connector facing the rear and balun connectors facing forward.
4. Before installing the balun, thread a 3/8” SEAL NUT all the way onto each connector, with the black
Neoprene face of the nuts facing out. Attach balun to the Block and tighten the connectors gently
using a 7/16" end wrench. Once the connectors are tight, back the Seal Nuts out and finger-tighten
firmly up against the face of the connectors (or tighten gently with 1/2” end wrench). A lot of torque is
unnecessary. Form the balun close to the boom and secure with a nylon cable tie. Tie should be snug
but not crushing or kinking the coax.
2M4 ASSEMBLY MANUAL
5. Install the 8-32 x 1/4” set screws (internal Allen head - tool supplied) into the SHORTING BARS.
Slide the bars onto the 3/16” rod driven element tips and then onto the Driven Element Block
Rods. Position the Shorting Bars as specified on the Dimension Sheet: 1-3/4”. Align the bars and
rods with each other and tighten the setscrews.
6. Insert the 7/8” x 9” REINFORCING SLEEVE into the rear of boom, flush with end. The boom to
mast plate is normally mounted at the rear. Use two 1" U-bolts and the stainless nuts and lock
washers provided (cradles are not used). DO NOT OVER TIGHTEN. 2” U-bolts are provided for
mounting the antenna to your mast.
THIS COMPLETES THE ANTENNA ASSEMBLY.
7. INSTALLATION AND STACKING INFORMATION
A. To protect your investment in this high performance antenna, always use high quality coax and
connectors. Old, corroded, or poor quality materials are common sources of serious performance
losses.
B. If possible, test the antenna, connectors and feedline BEFORE installing to your mast or tower.
At 6 feet or more the antenna will exhibit VSWR similar to higher mounting heights. Set antenna
on a ladder or temporary mast. Check for continuity and match across the rated bandwidth.
C. REAR MOUNTING: The 2M4 is easily rear-mounted in either horizontal or vertical polarity. A
metal mast or crossboom will have no effect on performance.
D. CENTER MOUNTING: Metal masts or crossbooms are OK for center mounting the antenna IF
they are at right angles to the element plane. ALWAYS use a NON-CONDUCTIVE mast or
crossboom IF it will be in the element plane. A metal mast in the element plane WILL adversely
affect performance. The feed coax, too, if routed to the center, must exit the boom at right angles
to the element plane. For example, with a vertically polarized antenna on a vertical non-
conductive mast, loop the coax out at a right angle from the elements and reattach to mast at least
6” below the element tips. Or, the coax can exit the rear of the boom and loop back to the mast.
Fiberglass is the prime material for a non-conductive mast because of it’s strength and weather
resistance. Wooden rod can also be used or thick-wall PVC pipe with a wooden rod inside for
support.
Carefully manufactured by:
M2ANTENNA SYSTEMS, INC.
4402 N. Selland Ave.
Fresno, CA 93722
(559) 432-8873 Fax: 432-3059
2M4 ASSEMBLY MANUAL
2M4 DIMENSION SHEET
Description Qty
Boom, 1 x .058 x 53" alum.................................1
Boom insert, 7/8 x .058 x 9.0" alum. ..................1
Elements, 3/16" rod alum. .................................4
“T” match block &1/4” rods ................................1
BTM plate, 3 x 4 x 1/8” (M2APT0019) ...............1
Balun, RG-6.......................................................1
U-bolt and cradle, 2" ........................................2
U-bolt, 1" ...........................................................2
Assembly instructions........................................1
Hardware Bag
Shorting Bar (M2ASB0090) ...............................2
Nut, 5/16-18 ss ..................................................4
Lock washer, 5/16" split ring ss .........................4
Nut, 1/4-20 ss ....................................................4
Lock washer, 1/4" split ring ss ...........................4
Setscrew, 8-32 x 1/4” int. Allen head, ss ...........4
Screw, 8-32 x 1-1/4" pan head ss......................1
Seal Nut.............................................................2
Button insulator 3/16" black polyethylene ..........8
Shaft retainer, 3/16" ss ......................................8
Push tube, 3 x 3/16" (retainer tool) ...................1
Allen wrench, 5/64"............................................1
Cable tie ............................................................3
M2ANTENNA SYSTEMS, INC.
4402 N. Selland Ave.
Fresno, CA 93722
(559) 432-8873 Fax: 432-3059
2M4 PARTS & HARDWARE
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