M2 Antenna Systems 249CP24 User manual

M2 Antenna Systems, Inc. 4402 N. Selland Ave. Fresno, CA 93722
Tel: [phone] Fax: [phone] Web: www.m2inc.com
©2022 M2 Antenna Systems Incorporated 08/22/22
Rev.01
Model ........................................249CP24
Frequency Range ......................244 To 254 MHz
*Gain ..........................................14.74 dBic
Front to back ..............................20 dB Typical
Feed type ...................................“T” Match
Feed Impedance. .......................50 Ohms Unbalanced
Maximum VSWR........................1.5:1 Typical
Input Connector..........................“N” Female
Power Handling..........................1.5 kW
Boom Length / Dia..................... 153” / 1”
Maximum Element Length......... 23”
Turning Radius: ......................... Call
Stacking Distance...................... Call
Mast Size................................... 1-1/2” to 2” Nom.
Wind area / Survival .................. 0.89 Sq. Ft. / 100 MPH
Weight / Ship Wt........................ 7 Lbs. / 9 Lbs.
M2 Antenna Systems, Inc.
Model No: 249CP24
SPECIFICATIONS:
*Subtract 2.14 from dBi for dBd
FEATURES:
The 249CP24 is high performance circular polarized antenna with a remarkably clean pattern. The pattern is
important in order to match the antenna’s noise temperature with modern low noise preamps. This antenna is ideal
for satellite work but is also excellent for terrestrial uses.
The CNC machined driven element module is O-ring sealed and weather tight for low maintenance and long-term
peak performance. Internal connections are encapsulated in a space-age silicone gel that seals out moisture and
improves power handling. The 3/16” 6061-T6 rod elements are centered to minimize interaction and maintain good
ellipticity. Insulators are UV stabilized and locked in place with stainless keepers. Rugged construction,
uncompromising performance for the boom length.

249CP24 DIMENSION SHEET

249CP24 ASSEMBLY MANUAL
ASSEMBLY INSTRUCTIONS FOR THE 249CP24
Before beginning assembly, read over the parts list and check for missing or damaged parts. Contact the M2
Antenna Systems, Inc. directly, [phone] if any discrepancy is found.
Tools required: A medium size flat blade screwdriver, an 11/32 nut driver or equivalent, a 1/2 inch wrench or
nut driver, a 7/16 inch wrench and a tape measure.
1. The driven element is partially assembled at the factory. Starting 13-3/4” (13.75”) from the rear of the
boom, mount this driven assembly to the boom so the two female “F” connectors point toward the front of
the antenna. Secure with an 8-32 x 1-1/4” screw. Next, slide the 3/16 x 23.0 inch long rod through the
open holes just below it and add two black button insulators. Center the rod in the boom. Add the shorting
blocks, positioning them at the ends of the shorter rod elements. When everything is adjusted, tighten up
the set screws.
2. Repeat this operation for the second driven element, mounting it at 25-1/4” (25.25”) from the rear and with
the two “F” connectors facing the rear driven element just installed and on the left side of the boom per the
sketch. Proper positioning per the sketch will guarantee RIGHT HAND CIRCULARITY.
3. Assemble the boom per the antenna dimension sheet, secure the joints with the 8-32 x 1-1/4” screws, lock-
washers and nuts. Final tightening and alignment will be done after the elements are all in place.
4. Now mount the phasing block 9-1/2” from the rear of the boom using an 8-32 x 1/4 inch screw. Position the
block on the same side of the boom as the rear driven element so the large “N” connector is facing to the rear.
REFER TO THE CABLE ASSEMBLY SKETCH FOR STEPS 6, 7 & 8
5. Connect the two 18.0 inch long balun cables to the two close spaced connectors on each driven element
block. Tighten the connectors first by hand and then gently but firmly with a 7/16 inch end wrench. TO
PREVENT POSSIBLE CABLE DAMAGE hold the body of the connector with pliers so it doesn’t rotate during
this final tightening operation.
6. Connect the long, 27-3/8” phasing cable to the single TOP connector on the FRONT driven element and
route the cable back to the side connector on the phasing block. Again, tighten both ends first by hand and
then finally with the 7/16 inch wrench.
7. Connect the short 9-1/8” phasing cable to the single connector on the rear driven element block and route
the cable to the in line connector on the phasing block. Tighten as before.
8. Once the cables are all in place form them neatly against the boom and hold in place with the black nylon
ties. In places where director rod elements will come through the boom, do not tighten the nylon ties all the
way so the cables may be moved slightly for clearance around the rod elements.
INSTALLING THE ELEMENTS
9. Separate the rod elements into two (2) sets. Using just one set, install the 22-7/8” rod element in 5/16 inch
diameter hole 5 inches form the rear of the boom. Use the black button insulators on either side where the
element passes through the boom. At this time just position the element near center. Final centering can be
done later when all the elements in one plane are in place.
10. The elements taper in length so continue installing the rods down the boom using the button insulators as
described in step #10.

249CP24 ASSEMBLY MANUAL
11. When all the elements in one plane are in place, start at one end using a tape measure. Center each
element to 1/16 inch or better. We recommend you DO NOT install the keepers at this time, just center each
element. When centering is complete, stand at the end of the boom and sight down the tips of the elements
noting any irregularities. The tips should form a gentle curve and each side should look like a mirror image of
the other. This is just a crude check to catch major errors or any irregularities. Correct if found.
12. The stainless steel element keepers are stiff so grasp the element firmly while sliding the keepers in place.
USE THE 3/8” X 3” TUBE TO AID IN THE INSTALLATION. Double check your centering dimensions and then
push the keepers up tight against the button insulators.
13. Repeat steps 10 through 13 for the other set of elements.
14. Now that all the elements are in place, sight down the boom looking for the element alignment irregulari-
ties around the boom splice joints. Align and tighten.
15. Pick up the boom and find the weight balance point. Remember the feedline will attach at the rear and add
a bit more weight on that end. Position the boom to mast plate accordingly, attaching it to the boom with the
1-1/8 inch U-bolts, cradles and nuts.
16. Circular Polarized antennas such as this antenna must be mounted on non-metallic masts or support
booms and the feedlines must run off the back of the boom so as not to disturb the standing wave ratio and
the circular properties of the antenna. If this antenna is to be mounted as a par of transmit-receive antennas a
6 to 8 foot long by 1-1/2 inch diameter cross boom is recommended. When attaching the main 50 ohm
feedline, tape or nylon tie it securely to the rear stub of the boom to remove stress on the male “N’ connector.
THIS ANTENNA HAS BEEN CAREFULLY MANUFACTURED BY
M2 Antenna Systems, Inc.
4402 N. Selland Ave.
Fresno, CA 93722
[phone] Fax [phone]
www.m2inc.com email: [email protected]

249CP24 PARTS LIST
DESCRIPTION QTY.
Boom section, 1” x 0.058 x 60" SOE .................................. 2
Boom section, 1” x 0.058 x 38" PLAIN................................ 1
Elements, 3/16" Alum. Rod x (See Dim Sheet) ................... 24
Driven Element Block Assembly .......................................... 2
Junction Block Assembly (SADE0065) ............................... 1
Balun, RG-6U X 20” ............................................................. 2
Phasing Line, Short (RG-6).................................................. 1
Phasing Line, Long (RG-6) .................................................. 1
Shorting Bars ....................................................................... 4
Boom to Mast Plate, 3 x 4 x .125" (M2APT0019) ................ 1
Assembly instructions ......................................................... 1
HARDWARE
U-bolt and Cradle, 2" ........................................................... 2
U-bolt, 1" No Cradle ............................................................ 2
Nut, 5/16-18 ss..................................................................... 4
Lockwasher, 5/16" ss........................................................... 4
Nuts, 1/4-20 ss..................................................................... 4
Lockwasher, 1/4-20 ss ........................................................ 4
Button insulators, 3/16" black ............................................. 50
Shaft Retainers, 3/16" ss ..................................................... 50
Screw, 8-32 x 1-1/4" pan head,ss ....................................... 7
Set screw, 8-32 x 1/4" ss .................................................... 8
Locknut, 8-32 ss................................................................... 4
Allen wrench, 5/64" ............................................................. 1
Push tube, 3/8 x 3" (for retainer installation)........................ 1
Nylon cable ties, 8" .............................................................. 5
M2ANTENNA SYSTEMS, INC.
4402 N. Selland Ave.
Fresno, CA 93722
[phone] Fax: [phone]
www.m2inc.com Email: [email protected]
249CP24 PARTS & HARDWARE