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Emergency 2 meter antenna

tom lish II (N6AJR) on March 29, 2001
View comments about this article!

While out fishing with a friend (non-Ham type) several years ago, I broke my Mag-Mount antenna for the 2 meter mobile rig I was bringing on the boat for communications purposes..this was in the days before cell phones. As I stepped on the boat, I managed to break the antenna off at the base of the mount, rendering it absoultely usless. We were going out fishing in the Northern California Delta for 3 days, so I had to come up with an alternative antenna.

I took out my trusty pocket knife and cut the coax off the mag mount about a foot from the mount ( never know when ya might need a mount with a short cable ) and stripped the outer insulation off the coax for about 19 inches ( I used two "extended hand width's" to measure as my fingers will cover about 8 1/2 inches fully extended, pinkey to thumb, try it, as it is the width of most pieces of school paper or typing paper, 8 1/2 " X 11 "). I then very carefully pushed and pulled on the outer braid of the coax and turned it inside out on the outside of the coax. It is a tricky job but you can do it... any how, I then had my friend pull the boat over near a tree ( willow tree to be precise) and cut of a branch about yea long and straight (probably about 45 inches). I then taped the newly made antenna to the branch and tried it on the two meter mobile for size and it worked just fine. We used the rig with the stick supporting the antenna taped to a piece of railing on the boat and actually made excellent qso's to the repeaters we were using to keep in touch with the family.

Bye the way, I always carry a roll of electrical tape in my tackle box. I use it for putting guides back on the pole and stuff like that, I suppose I could have tied the antenna to the stick with fishing line if I didn't have any tape.

Any how, I ran the insulated center conductor up the stick and laced the whole thing together with the tape. I found out later while describing this thing to a Ham friend that I had made a 1/2 wave coaxial antenna for 2 meters, and you can buy them commercially (somewhat better made) as the coaxial antenna actually has some gain over a half wave dipole, something about the coax being electrically disconnected from the antenna at rf frequencies due to the coaxial shield covering the outside of the feed raising the feed point on the antenna.

I told him how nice that was and all, but it sure worked well on the boat, and we caught lots of fish, and had a great time, which is probably what matters most.

73's... Tom Lish N6AJR

Member Comments:
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Emergency 2 meter antenna  
by N6AJR on March 20, 2001 Mail this to a friend!
While reviewing some of my old QSL card I figured out I got my license in 1978 or 1979 as I can't find a qso card dated earlier than that. I don't suppose it makes much difference these days. I wish I could find my old "first" call book with my call in it the first time. tom N6AJR
 
Emergency 2 meter antenna  
by W8MRA on March 29, 2001 Mail this to a friend!
I have made at least 15 antennas for the UHF business radios we use at work the same exact way. Where I work there is a lot of overhead crane movement. People tend to want to hit things. Used to be we would lose an antenna about once every six months. Now they can wack at one of my "rubber antennas" and it bounces right back. I've also made antennas for forklifts the same exact way. No more worry that the rolling door they are driving under is just a little too low. There's also zero chance of the antenna vibrating itself apart when its mounted to a rough running vehicle like a forklift or locomotive.

-73
 
Emergency 2 meter antenna  
by KC7BDP on March 30, 2001 Mail this to a friend!
I use the same antennas nearly every year for a 7 day long event here in Yuma. Been using Land Mobile equip't for commo at our Jaycee Chapter's annual Rodeo for the past 7 years; usually the fixed stations use a mag-mount on a folding chair (in the "folded" position) set up on a shelf or travel trailer roof. One year the source of free mag-mounts failed us. I ended up making 3 coaxial antennas (9.125" for 461MHz- counting velocity factor) to cover the shortage; taped to windows, Fiberglas trailer walls, etc. One radio lived in an office under the arena's wooden grandstands; I used 50' Rat Shack el-cheapo RG-58 with the coaxial antenna in place of the chopped off crimp-on PL-259; and had to shorten the "center conductor" about 1/2" to counteract the coupling of the roofing nail I wrapped the end of it around. Great SWR (anybody that has lived with a Moto Maxtrac can tell you about SWR problems); and the sucker flat out TALKED and HEARD!

I'm back to using mag-mounts almost everywhere; except that office under the grandstands. That's the radio that gets used when we need to talk to somebody verrrr-rrrry far away.

Jimmy
KC7BDP
 
RE: Emergency 2 meter antenna  
by NB6Z on March 30, 2001 Mail this to a friend!
A 1/4 wave whip antenna without the groundplane is not a good 50 ohm match to the radio and therefore not very effecient; but obviously it will radiate and receive.
 
Emergency 2 meter antenna  
by KC0IEE on March 30, 2001 Mail this to a friend!
This is one of my most favorite things about being a ham, adapting to adverse situations. It's very doubtful many public service radio users would have been able to adapt in a similar situation. I wish more agencies would take advantage of our services. good story.
 
Emergency 2 meter antenna  
by KG6FUT on March 30, 2001 Mail this to a friend!
Good story.
But how many watts pep were you running? Anyway I have a spare ant. in the car for problemes like this but if you didint that would be a good alternative. 73 de KG6FUT
 
Emergency 2 meter antenna  
by N6AJR on March 31, 2001 Mail this to a friend!
I believe it is actually a center fed half wave coaxial verticle if ya checks the design. I pulled the braid over the outside of the coax, which isolates the rf from the transmision line and keeps it from being a verticle half wave dipole. and raises the feed point resistance, or so they say. I was only running about 25 watts on it any how.

I once use an 8' 6" piece of coax stripped back like a dipole to test a Yaesu 101EE I was buying from a CBer.. he was amazed I could make a real antenna, and got a radio check from another ham in Florida from northern California.He said he never got that far on his starduster..lol. With that one I did make it a dipole because it is too hard to reverse over 8 feet of braid... easier to pull the center conductor out the side.

tom
 
RE: Emergency 2 meter antenna  
by N7JAU on April 7, 2001 Mail this to a friend!
What is a radio check?
 
RE: Emergency 2 meter antenna  
by NA6MB on April 9, 2001 Mail this to a friend!
A radio check is the payment for that new radio you just got!

73 de Mike
 
RE: Emergency 2 meter antenna  
by K3UOD on May 18, 2001 Mail this to a friend!
This antenna used to be in the handbook (or maby it was Hints 'n Kinks) at one time. Perfectly good design. You can stick it inside a piece of PVC pipe for a more permanant and weather proof arrangement. Impeadance is really closer to 73 ohms but that doesn't make a lot of difference. Some people are overly fussy abt VSWR. Some people use a length of RG-59 as a matching transformer, which is a good idea if you have the materials and time to fool with it. In an emergercy, any antenna that works is a great antenna.
 
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