M2 Antenna Systems 2M18 series Assembly Manual

M2 Antenna Systems, Inc.

Model No: 2M18XXX

Gain for single antenna

Gain for two atennas

stacked vertically as pictured

Gain for 4 antennas

stacked 2 x 2

SPECIFICATIONS:

Model ......................................... 2M18XXX

Frequency Range ....................... 144 To 146 MHz

*Gain for 1 / 2 / 4 ........................ 17.14 / 20.14 / 23.14 dBi

Front to back .............................. 26 dB Typical

Beamwidth ............................... E=26° H=28°

Feed type ................................... “T” Match

Feed Impedance. ....................... 50 Ohms Unbalanced

Maximum VSWR ........................ 1.2:1

Input Connector .......................... “N” Female

*Subtract 2.14 from dBi for dBd

Power Handling .......................... 1.5 kW

Boom Length / Dia ...................... 36.5’ / 1-1/2” to 3/4”

Maximum Element Length .......... 41”

Turning Radius: .......................... 19’ 6”

Stacking Distance ....................... 14’ High & 14.5’ Wide

Mast Size .................................... 2” Nom.

Wind area / Survival ................... 2.9 Sq. Ft. / ?? MPH

Weight / Ship Wt. ........................ 14 Lbs. / 16 Lbs.

FEATURES:

The 2M18XXX has been extensively used by many moonbouncers and other weak signal enthusiasts for
the last eight years. The clean, sharp pattern yields a very good G/T (gain/temperature in K) which, in everyday
language, means you he ar more signa l and le ss noise. It is ideal as a single antenna or in stacked arrays of 24 or
more antennas, yielding a full 6 dB of stacking gain for four antennas! Mechanically, the boom is strong in the mid­dle and tapered in 1/4” steps to reduce weight and wind area. M
with the unique driven element module. The aluminum CNC machined housing features “O” ring seals on all three
connectors and internal connections are potted in silicon gel than enhances the power handling capability. That is
important to those who feel life is too short for QRP (Low power)! All hardware is stainless except the U-bolts. By all
standards the “18XXX” is a true thoroughbred among VHF antennas!

2

has integrated the computer optimized design

M2 Antenna Systems, Inc. 4402 N. Selland Ave. Fresno, CA 93722

Tel: [phone] Fax: [phone] Web: www.m2inc.com

©2015 M2 Antenna Systems Incoporated

05/26/15

Rev.00

2M18XXX ASSEMBLY MANUAL

TOOL REQUIRED: Flat blade screwdriver, 11/32 nut driver or socket, 7/16 and 1/2 end wrenches and / or

sockets, measuring tape.

1. Start by laying out the boom sections using the DIMENSION sheet as a guide. Use 8-32 X 1­1/4 screws and locknuts to join 3/4” to 1” sections; 1-1/2” screws for 1” to 1-1/4” sections; 1-3/4”
screws for 1-1/4” to 1-1/2” and 1-1/2” to 1-1/2” sections.

Assemble the three 1-1/2” sections first. The center 1-1/2” section, swaged on both ends, has

an element hole 13-1/4” from the “rear” end. Find the 1-1/2” section with 5/16” element hole 17­1/16” from swaged end. Assemble this section to “rear” swage of center section. Assemble
remaining 1-1/2” section to “front” of center section. The 1-1/4” section with 3 element holes is
assembled to the rear; 2 hole section to front. The straight 1” section is the rear of the boom; the
swaged section is to the front. The 3/4” section is the front of the boom.

To make assembly easier, support the completed boom about waist high on bucks, tables, etc.

Or, drive a 1-1/2” to 2” pipe into the ground and temporarily attach boom using boom to mast plate
and U-bolts at balance point.

2. Lay out the elements by length and position as shown the DIMENSION sheet. Start with the
reflector (40-7/8”) element.

in diameter from run to run. If buttons are loose on the rods, squeeze each button
slightly before pushing it onto the rod. This will help hold the element on center
during keeper installation. Balance across finger to find center and push on a black button

insulator to about 1/2” from center. Insert the element through the holes 1/2" 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
internal locking “KEEPERS” yet. This is easier to do after all the elements are installed in the
boom.

3. Install the 3/16” X 41” rod DRIVEN ELEMENT as you did the reflector. Then continue with the
installation of the DIRECTORS. Note that the Director Elements do not consistently diminish in

length from rear to front, so pay close attention to length and position.

4. Now begin centering the elements. Use a tape measure to EQUALIZE the element length on each
side of the boom. Once you have all the elements centered, sight down the element tips from the
rear comparing each side. Look for any obvious discrepancies and correct if found.

5. Begin installing the stainless “keepers.” Use thumb and index finger to hold a keeper over end of
the 3/8 x 3” push tube (keeper dished into tube).

champhering the inner end of the tube where you place the keeper.

firmly and start the keeper onto the rod by applying pressure with the push tube. Push the keeper
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 keeper too far).
Repeat for the opposite side. Continue installing keepers until all elements are locked in place.

6. Mount the DRIVEN ELEMENT BL OCK ASSEMBLY to the top of the boom using a single 8-32 X 1­1/4" screw. Orient the block with feed connector facing forward and balun connectors facing to
rear.

7. Before installing the balun, thread a 3/8” SEAL NUT all the way onto both connectors, with the
black Neoprene side of the nuts facing out. Attach balun connectors to the Block and tighten
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 very gently with 1/2” end
wrench). 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.

8. Install the 8-32 x 1/4” set screws (internal Allen head - tool supplied) into the SHORTING BARS.

NOTE: Buttons and rods vary a few thousandths of an inch

NOTE: Add keeper finger relief by

Hold the element