M2 Antenna Systems 25M4 Assembly Manual

SPECIFICATIONS:

Model ........................................ 25M4

Frequency Range ...................... 11.9 To 12.10 MHz

Gain ........................................... 9.52 dBi

Front to back .............................. 21 dB Typical

Feed type ................................... Hair Pin Match

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

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

Input Connector ......................... SO-239/Others available

The 25M4 was designed for high performance while keeping weight, wind area and costs low. Using computer

optimization techniques, every bit of the design has been squeezed for performance. The 25M4 can be stacked for

improved performance. The 1:1 Fairite balun and low loss hairpin match help maintain high efficiency. Element ring

clamps and other important components are CNC machined for maximum strength and electrical integrity. All antenna

hardware is stainless steel and the U-bolts for mounting are zinc plated.

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

M2 Antenna Systems, Inc.

*Subtract 2.14 from dBi for dBd / FS = Free Space

Tel: (559) 432-8873 Fax: (559) 432-3059 Web: www.m2inc.com

Model No: 25M4

Power Handling ......................... 3 kW, Higher avl.

Boom Length / Dia ..................... 40' / 2 1/2"

Element Length / Dia. ................ 34' / 1-1/4"-3/8"

Turning Radius: ......................... Call

Stacking Distance ...................... Call

Mast Size ................................... 2" to 3 " Nom.

Wind area / Survival .................. 3.5 Sq. Ft. / 100 MPH

Weight / Ship Wt. ....................... 65 Lbs. / 75 Lbs.

08/30/22

Rev.01

Table of Contents

Do you have a question about the 25M4 and is the answer not in the manual?

Page 1 The 25M4 was designed for high performance while keeping weight, wind area and costs low. Using computer optimization techniques, every bit of the design has been squeezed for performance. The 25M4 can be stacked for improved performance. The 1:1 Fairite balun and low loss hairpin match help maintain high efficiency. Element ring clamps and other important components are CNC machined for maximum strength and electrical integrity.
Page 2 25M4 ASSEMBLY MANUAL NOTE: A cup of zinc paste (PENETROX, NOALOX, or equivalent) has been provided to enhance the quality of all the electrical joints and make assembly and disassembly easier. Apply a thin coat wherever two pieces of aluminum come in contact.
Page 3 25M4 ASSEMBLY MANUAL 8. Now adjust ELEMENT SPACING accurately following the Dimension Sheet. Dimensions given are “center to center” or common edge to common edge. After setting spacing, align elements and tighten the 1/4-20 x 1” bolts at the bottom of each ring clamp.
Page 4 D.E. & PARASITIC ELEMENT DETAIL...
Page 5 25M4 DIMENSION SHEET...
Page 6 25M4 PARTS AND HARDWARE DESCRIPTION BOOM SECTION, 2-1/2” X .058 X 84” SWAGED ............... 5 BOOM SECTION, 2-1/2” X .058 X 72” ................1 ELEMENT SECTION, 1-1/4” X .058 X 60” SOE ..............8 ELEMENT SECTION, 1” X .058 X 60” TYPE 1 (SOE) ............8 ELEMENT SECTION, 3/4”...