In reply to M3EDX:
Got Mine today, just picked it up, On charge as I write.
Have ordered an adaptor from Peter at Garex and have just got some Twin feed ribbon to make up a Slim Jim for use with it.
once all tested will be doing a 4m activation from a summit near you soon.
73
Tony
In reply to M6ADL:
Take a look at http://www.summitsbase.org.uk/tiki-index.php?page=4m+J-pole for
J pole measurements that actually work - use the black slotted cable.
Roger G4OWG
In reply to G4OWG:
use the black slotted cable.
Couldnāt get either the measurements on the Four Metre Forum or Summitsbase to work. The first one seemed to tune up at 92MHz (canāt understand why because it shouldnāt) and the 2nd one at 72MHz (3:1 at 70.400). Maybe it is because I am using grey 300 ohm slotted cable and not black?
Out of time so didnāt get chance to play any more and get it to work.
Steve GW7AAV
PS Found half a dozen 4m Slim Jims and J-poles on the net and every one quotes different dimensions.
In reply to GW7AAV:
You must use the Black Slotted for the Summitsbase Dimensions Steve - I cut mine from a redundant G5RV 
Roger G4OWG
In reply to G4OWG:
Forgive me but isnāt the usual black slotted cable that comes with all good G5RVs 450Ohm?
You could measure the Zo of the cable you have. How to do this is left as an exercise for the reader
Andy
MM0FMF
In reply to MM0FMF:
Ideally yes Andy - but most ready built RVs from the likes of Moonraker etc use
300ohm heavy duty slotted black. About 10mm across as opposed to the 22mm across 450ohm.
Roger G4OWG
In reply to G4OWG:
Moonraker
'Nuff said 
I used the clear plastic lightweight 300Ohm cable. I got it from Maplin (which I normally donāt use but it was a Sunday when I made mine.)
Andy
MM0FMF
In reply to MM0FMF:
I thought of using the lightweight stuff Andy, but Mike G4BLH gave me dimensions for the heavier black 300 ohm ribbon, so I obtained some of that. I bought mine from Waters and Stanton : 300-S 300 Ohm Slotted Ribbon Cable. Iāve made two so far and both gave me 1.3:1 when hanging in the stairs at home, somewhat better on the pole at 5m. Resonance indoors was a tad HF of 69MHz, but it rises in frequency when outdoors and the SWR improves. I use about 7 turns of coax wound and tie-wrapped just below the bottom of the antenna as a choke. All in all the design works for me.
Mikeās dims are: bottom to feed point - 78mm; bottom to gap 880mm, gap 45mm; gap to top of antenna 1943mm, all as per the Summitsbase article. I use electrical tape to reinforce the section where the gap is positioned as the ribbon is without the conductor at that point.
73, Gerald
In reply to G4OIG:
I suppose the velocity factor of the cable will be different between the light and heavier versions of ribbon cable and that may account for the fact that your dimensions look wrong to me. The 1/4wave bit and stub looks a bit too long.
Iāve got a lightweight version for 2m where match is very good over a substantial portion of the band. Scaling that by a factor of 145.5/70.3 will give the dimensions for one built from the same cable for 4m. Iāll measure it tonight. Iād make for 4m and measure its performance one but I havenāt got any more cable.
Andy
MM0FMF
In reply to MM0FMF:
Hi Andy,
I thought the feed point was rather low, but it does match okay. Steve G1INK built one the same and we have both had contacts with G6LLX down in the Forest of Dean from Shining Tor SP-004 (separate occasions), so they certainly work.
73, Gerald
In reply to G4OIG:
Mikeās dims are: bottom to feed point - 78mm; bottom to gap 880mm, gap
45mm; gap to top of antenna 1943mm, all as per the Summitsbase
article.
As mentioned in the article, the dimensions are not from me but from Ian GW8OGI, and, as they say, āit works for meā (and Gerald, and Inky and of course Ian). I have now built 3 of these, all show a VSWR (when up on the pole) of around 1.2:1 and āon the airā testing shows that they do work extremely well.
Mike G4BLH
Coming to this late, only getting the daily digests, some of you may recall my attempts in 2007 to use 4m. Seems that there may be a better chance of making QSOs on the band this year!
Back then I made an antenna from the top section of a fishing pole - the piece I always find far too bendy for rigging a summit antenna. It may be of interest. It certainly tuned up well and performance was great. Also, itās quite durable for surviving the summit approach. (Mineās lasted two years so far, anyway.)
Link is http://www.m0jrq.com/site/pages/projects/antennas/4m_whip/index.php to some notes and pictures.
73
Chris
M0JRQ
In reply to M0JRQ:
Nice one Chris!
I have to say I have been looking at those top two sections of my fishing poles and thinking there must be something I can do with those. It looks like you found the problem to fit a solution that was staring you in the face like it has been me. I even got as far as tapping a small piece of fibreglass tube from a windbreak so it fitted into an PL-259 with the idea of gluing the top whip to it. My idea had been to make a simple 1/4 wave (no coil) for on the car by running a wire inside the tube.
Got to make the J-pole work for me first but I will have a go at something similar to your idea shortly.
Regards Steve GW7AAV
In reply to GW7AAV:
I have it on good advice that a chickenbox DV-27 will work well on 4m without mods. Of course I learned this days after selling a job lot of 8 such beasts from an SK sale.
I was playing with my 2m J-pole last night, checking its match with the idea of scaling it for 4m. I wanted to see how close the measurements are to the ones Gerald gave, These things do seem to be very sensitive to nearby by items detuning them, more so than some other 2m antennas Iāve used. Mine also was prone to getting RF onto the outside of the coax. I think a few chokes are needed, one on the feedline and one on the 817ās power cable.
Andy
MM0FMF
In reply to anyone:
I have been stuck inside for a couple of days (while my daughter was sick) so decided to experiment with J Poles on my network analyser. The ability to see a wide frequency spectrum made it easy to understand how to adjust a J Pole. The following might be off some use to someone ā¦ somewhere ā¦
I soon learned that the critical part of the antenna is the stub and the related tapping point. Once you have this adjusted correctly then you can lengthen and shortern the radiator to vary the frequency over a very wide range, without significantly affecting the match.
The problem is that there are three seperate adjustments, so I made an easily adjustable J Pole out of bare copper wire, the tapping points slid along the stub wires, a shorting bar adjusted the stub length and the radiator just folded over at the top. I used this to learn the ropes.
This produced excellent results and it was easy to get a 1:1 match and no rf on the coax shield problems.
The next problem was how to do the same with 300 ohm twin feeder. To save wasting feeder I seperated the J pole into three parts, the radiator was made out of pvc covered 32/0.2mm wire, the top part of the stub (above the tap) from 300 ohm twin feeder and the bottom part of the stub from bare copper wire with a shorting link to vary its electrical length. All the above were connected together to form a J Pole.
The method of tuning was to vary the shorting bar to find a 1:1 match, this frequency was initially low as the stub had been deliberately cut a little long. I then iteratively pruned the 300 ohm feeder and varied the shorting bar until the resonant frequency was correct. During this I also varied the length of the radiator to see the effect.
The next step was to replace the bare wire stub with a stub made out of 300 ohm feeder and its length was then adjusted for the 1:1 match.
Fine tuning then took place by varying the radiator length.
The overall result was a very well behaved J Pole with a perfect match.
Note that I did use a good choke on the feedpoint.
The next experiment was to see if I could tune the stub without a radiator attached. The idea behind this was that at resonance the radiator would present a high, but not infinite resistance at its end feedpoint (non reactive). Cutting a long story short, I connected an 8k7 resistor across the stub at the end where you would normally connect the radiator. I then tuned the stub length and tapping point to give a 1:1 match at the desired frequency. The resistor was then replaced by a radiator and pruned to the desired frequency.
As a final experiment I made some J Poles out of twin speaker wire, much cheaper than twin feeder, lower profile and a much shorter stub due to the velocity factor. I have only tested with 5w, but they work fine at that power level.
Hope this is of some use to someone.
Regards,
Nigel. G6SFP.
In reply to G6SFP:
Greetings from EA8, listened on Wouxun today but nothing heard
ps 33C today with Easterly wind direct from the Sahara.
73.
In reply to G1INK:
Thatās way too hot for me Steve
Iām sure I heard an EA calling CQ on 4 Metres a couple of hours ago, but that couldnāt have been you, could it?
By the way, Iām very tempted to join the club & purchase one these Wouxonās for myself, they do seem to be excellent little rigs for the price!
Have a good holiday Steve.
73 Mark
In reply to G0VOF:
Hi Mark.I have just knocked together a J pole as mentioned by G4OWG on the 10th of March on this thread.I made to it Mikes (G4BLHs) instructions and was amazed on how well it performed.I used it yesterday on NP010 Great Whernside with good signals reported all round.I got six contacts which Mike thought was good for a weekday.The Wouxun is a nice little rig for the price.I hope you will join the clan. ATB 73 Geoff G6MZX
In reply to G6MZX:
Wouxun 70MHz KG-699E slovenian clan in this moment: S57OPZ, S57XX, S58MU, S57BNX, S57D. :-)))
73, Milos S57D
In reply to G1INK:
Hi Steve,
enjoy your holidays! Are you QRV on HF in EA8? I would like to try a QSOā¦
good luck, 73 de Lutz