"International friendship through radio "

 
Portable j-Pole for 2m and 70cm
 
  This project came about from the need for more gain without looking silly staggering about with a 9ele 2m yagi fully assembled and connected to the rucksack (dont laugh, I have a picture on file of somebody who does just that, in good old Am-er-ee-ca! he also wanders arounf the Rockies with a full size 40m quarter wave on a back pack, hmmm). The supplied rubber duck on the FT60E is less than fantastic so I needed something light weight, not too big, no radials, that would work on 2m and 70cm and out perform the the supplied yaesu wet string. Trawling the net pulled up a couple of likley looking options. Been a true Yorkshireman I needed something cheap to build.  
  The j-pole shown here was a real dog to get running, anything near the stub effected the tuning to the point of red zone swr readings, luckily the rucksack seperates me from the j-pole and the tune is adiquate. Been battery powered the overs are usualy short anyway, and the power is reduced to prevent an oven ready operator. I can report that the performance is nothing short of outstanding by comparison to the RD antenna.  
  The basis of this antenna is a length of 300 ohm ribbon cable, an offcut of B+Q electrical conduit and a couple of sticks worth of hot melt glue. Cut the ribbon to the dimentions shown, expose the conductors on the stub end of the wire, short the end as shown, solder on the coax and hang it up somewhere. I have a ladder rack in the garage that is pretty useful for this task. I also use mans greatest invention for the tuning of antennas, nameley an MFJ antenna analyser..If tuning is required, prune a bit off the radiator (long end) to bring it somewhere near, dont get too hung up on a 1:1 match, your rucksack is going to de-tune it anyway - or maybee not, isn't RF great.  
  When happy that it was "there or thereabouts", I potted mine in a length of electical conduit (plastic obviously) and sealed the ends with hot melt glue and a natty end cap "sample" that was procured from a supplier (work has it's uses sometimes). Incidentaly you only need to glue the top of the conductor to the tube and the bottom of the stub to the tube. There is no advantage to filling the tube with glue, too heavy and too expensive, unless you are a glue salesman, in which case fill your tube up, oh, and if you can swing it I am always greatfull for a freebie or two... The choke hangs in the breeze but is fully waterproofed with hot melt glue.  
 

In use the j-pole is lightweight and works well. I also noticed that it has some directional properties, the body appears to sheild (absorb?) the RF slightly. Due to the length of the 'pole, it can also drag bits of branch and birds nests down on top of you, and on one occasion a dicarded ice cream wrapper (wet side out - nice), anyway, mind you dont hang yourself with it! One other warning, motorists tend to watch the pole rather than the road if you are near civilisation, swerving, hooting and wrong side of the road motoring are all symptoms. You have been warned!

I have used this from 2100 feet asl, with 20 watts from the FT857 with QSO's from the Pennines into Wales, south Coast and Scotland. It also works on 70cm too. For best performance suspend from a 6m pole and feed with a few meters of RG58.

On the rucksack from around 800 feet fed with 5w from an FT60E, distances of 150 miles are not uncommon.

 
 
I used the dimensions shown here as a start point.
 
 
Usual disclaimers apply - dont blame me if you microwave/hurt/maim yourself, or any body else..