|KC3GAB||CLARK, ANDREW C|
|KC3GAC||THOMPSON, JOHN P|
A Quick and Simple 2 Meter Ground Plane Project! If you are just getting experience in building antennas or you are an old pro, here is a simple and fun project! This antenna is perfect for those hams living in the primary coverage area of the repeater for 2 meter use.
This antenna is nothing more than the old standby “Droopy Ground-plane” and can be used on any band where it’s physical size does not pose a problem. Remember that the vertical radiator is 1/4 wavelength long at your operating frequency. It has no gain but makes an excellent small antenna that can be mounted just about anywhere and with a little planning, can be used mobile on a short mast from the bumper!! Adding a small
attachment loop at the tip of the radiator will enable it to be suspended from above for inside use. Build it! (See link to drawing below)
ground plane drawing
The vertical element and radials can be made of #12 copper wire or welding rods, coat hanger, etc. The vertical radiator (A) should be soldered to the center connector of the SO239. The four base radials (B & C) and (D & E) can be soldered or bolted to the SO239 mounting holes using 4-40 hardware.The four base radials then should be bent downward to a 45 degree angle. The antenna can be mounted by clamping the PL259 to a mast or
even passing the coax through a 3/4 ID PVC pipe and compression clamping the PL259. Either way let your creativity work for you.
If you plan on mounting it outside, apply RTV or sealant around the center pin and PL259, and tape well, to keep water out of the coax. Make each radial a 1/4 wave of your desired transmit frequency. Sometimes it helps to add a little extra length to the radials and radiator. This will give you some adjusting room when you adjust the SWR.
(If adjustment is needed, clip all radials equally about 1/8 inch at a time while checking SWR, USING LOW POWER). Center the lowest swr on your transmit operating frequency.
- Example Calculation:
Freq (MHz) 146
A (inches) 19 5/16 (Note “A” length is to the SO-239 insulator but not critical)
B THRU E (INCHES) 20 3/16
LENGTHS FROM FORMULA ( 234/FREQ MHZ) + 5 % LONGER FOR RADIALS
TRY ONE ON 440 or other bands USING SAME FORMULA AND CONSTRUCTION TECHNIQUES!
ENJOY AND EXPERIMENT!
DON’T TRY IT ON 75 METERS MOBILE……IT’ A LITTLE LONG FOR MOST BRIDGES, OVERPASSES, POWER LINES ETC!!!!
I came across this interesting article on emergency preparedness. It has some good points to consider. Let me know your thoughts.
Communications is the most neglected area of preparedness. Our smart phones have become an integral aspect of our daily routine. Their portability and ease of use makes them seem the ideal solution during a disaster. Nothing could be further from the truth. Cellular networks are in reality fragile systems that simply cannot be counted on during a disaster. These systems can be taken out of service by overloaded cell towers, natural disasters, significant weather events, power outages, forest fires, and terrorist attacks just to name a few at the top of a long list.
You need look no further than recent history to understand the importance of preparedness communications. During Hurricane Katrina and Hurricane Sandy communications failed because landline and wireless cellular phone service were knocked out of commission by power failures, hurricane force winds and massive widespread flooding. With no personal communications plan, residents were left without the ability to call for help or notify family and friends of their wellbeing. Most people also lacked the ability to keep phones and other devices charged and operational.
Bottom line, getting a radio and putting it on your preparedness shelf is inadequate and a sure recipe for failure in a time of need. To be truly useful as a preparedness communications tool you need to practice using your radio, have a communications plan, and practice the plan frequently.
Dare I say, prepare for the worst and hope for the best.
Have you heard on the air bands, ham’s saying one to another “73”?? Click below on “What does 73 Mean” for a brief rundown on its meaning and proper use.
443.300 – Plus offset (5 MHz), tone 67.0Hz
Has been repaired
Located on Blue Mountain at Lamb’s Gap near Enola, PA.
Gary WA3CPO and Scott N3SW went up to the Lamb’s Gap site to work on the APRS digipeater system that is now located there. Scott got some configuration information from the current Terminal Node Controller in preparation for replacing it with a newer TNC. When the new TNC is configured we will go back up the mountain to swap it out. Come out to our next SMRA meeting for updates on this project. Look for the photos in this gallery: APRS Digi at Lamb’s Gap
This Sunday, July 18, SMRA will once again be providing radio communication for the Curse of Dark Hollow bike race in Michaux State Forest. Here is some information you may find helpful:
- We generally use the 145.43 repeater out of Mount Holly Springs, but this may change depending on conditions and other technical factors. Here is some additional information about the frequencies we may use (Thanks to W0BR):
Main: 145.43, -600kHz offset, 67.0 Hz tone – Mount Holly Springs repeater
Secondary: 146.46, +1MHz offset, 67.0 Hz tone – Three Square Hollow repeater
Simplex: 146.58, no offset, no tone
Simplex (UHF): 446.00 no offset, no tone
If you are unable to come out to work the race, you can still listen in to see how it’s done. Bike races are a great way to learn how to do emergency communications (EMCOMM).
- We will be meeting for breakfast at the Cracker Barrel off Exit 47, I-81 in Carlisle between 6:00 and 6:30 a.m. I will have paper copies of the roster available.
- I need to emphasize this point: We are only there to provide communications support. We are not to direct traffic; bring water; or do anything other than communicate necessary information. Basically, what you do is to inform the net control station (NCS) if a rider needs assistance, either due to an injury or a mechanical breakdown. NCS then informs the race organizers that assistance is needed, and where. The race organizers have volunteers at each checkpoint who actually provide the water and other services. If you are asked to do anything that doesn’t involve a radio, let NCS know.
- In addition to your radio equipment, make sure you bring water, food, snacks, and something to do.
- If you have any questions, e-mail email@example.com or firstname.lastname@example.org
In spite of the weather we will still having our SMRA Field Day. The forecast calls for rain, heavy at times, (with an eastern wind 10 to 15 Mph) which is not in the best interest of our electronics, so we will be using the trailer. Space will be limited and we will do our best to accommodate all our stations and goals.
We will begin at 9:30 AM Saturday with set-up. VE Testing at noon and the contest officially begins at 2 PM.
Bring your enthusiasm, interest and rain gear!
Stay tuned to this web site for updates; or call N3TWT at 145.430 MHz for talk in or questions beginning Saturday 9:30 AM.
Our address is
Emergency Services Training Academy
180 Army Heritage Drive, Carlisle PA, 17013