Building a Great Portable Antenna for VHF or UHF.
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- čas přidán 19. 04. 2017
- Building a Slim Jim antenna for 6m. Links: m0ukd.com/calculators/slim-jim... www.hamuniverse.com/slimjim.html
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Wow I always enjoy your videos, I am a new ham (7 months) and I find building antennas and the testing them is so interesting. You are such a great teacher and I appreciate your skill knowledge and even tempered approach, you are inspiring thank you
Thank you, much appreciated!
I've never used ladder line but now I might try it. Thanks as always.
Copper rod and bnc adapter is a very nice way to make adjustable feed point!
J-pole is easier to make resonant at exact point wanted. Just make the cut like in slim jim and leave the unconnected piece of cable there. Do not connect the wires at the top. The extra piece of wire makes a little difference. Then just trim the lengh from end to adjust frequency and move feed point if the impedance is higher/lower than 50 ohms.
I made a one like that for 70cm. I did not have the feedpoint adjustment but a bit of wire wrapped before soldering can be moved around too. (or you may get lucky and the calculation is good enough).
Nice video Sir! I too made a ribbon slim Jim a couple of years ago using ladder line and this calculator. I also found the antenna to be too short. I went back to a design from many years ago (VHF/UHF Antenna hand book maybe??) And started again with much better results. One thing I did find was the coax was a bit "Live", so I added a choke at the feed point. Hth.
Excellent!
Great video RP. Very interesting. Some fantastic antennas.
Thanks.
About The Heating Up The Copper Rods, You Can PutThem In ThirdHand Or Some Vise And Then use A HeatTorch To HeatThem up And Then Solder Them, I have DOen That Hundeds Of Times And Every Time It Works For Me
a very valuable knowlledge thank you
Good Idea, easy and cheap to make!
You should heat the HeatShrink tube only with the blue part (near the lighter base)
of the lighter flame, as it heats but never BURN the tube. This is recommended by the tube manufacturers :) My 2 Cens.
L'utilisation de l'adaptateur pour oscillo est super bien pensée ! J'en ai commandé 4 sur eBay que je destinais à des dipôles pour le portable en QRP, mais ça me donne plein d'idées (y compris pour le feed-point d'une yagi avec un gamma-match, par exemple) !
Je n'en ai qu'un et franchement, c'est insuffisant!
Ton idée m'en a inspiré une tonne ! Je repars faire une commande ! :D
Interesting video. :)
I notice the velocity factor used is 0.91 (5.29/5.81), that's why the length ended up short? Maybe 0.93 or 0.95 would be better?
Probably..
Amazing video, I'm a big fan of you're channel! I'm doing a SOTA holiday soon and have a 5wFM handheld, Yaesu and I've made this Slim Jim for 2m. Do you think it would be worth it for me to buy a 50w transceiver and have the extra weight? Do you think the extra power will give me lots more contacts? Does the extra power cause the waves to bend round the Earth more, even if it is at VHF?
I do not think an amp is worth the added weight. What you need is altitude and a good antenna. Make a tape-measure yagi maybe...
@@RadioPrepper Many thanks for your reply. In that case I will take your advice and just use the handheld. I will use the slim jim as a radio ham told me that his slim jim had more gain than his 5 element yagi for 2m. I was surprised at this.
very simple and portable....I like it...
but Iam interesting too , the tool like you use tuning for this antena.
As antena analyzer...Would you like to share pls, Its about this analyzer spec...I think.. Iam going to try build this ant anlyzer
Thank U de YC2SAN
73
The analyser is the MR100, found on Ebay.
Outstanding
Hlw radio rapper i am using intercom radio i want to extand the range up to 5 km can i use this anteena or not?
Go to the M0UKD web site, find the Slim Jim calculator, given your working frequency, see if the measurements you get seem reasonable. I do not have enough information to answer your question.
May I know the portable antenna analyzer machine name and its application name?
Today I suggest the Nano VNA.
Great video, 73!
Coming from the audio/studio side of commercial broadcasting where for some applications we even use electrical contact grease, I am always surprised that amateur radio operators carefully put together antennas, keeping a close eye to every details, but, when it comes to the connector, suddenly, they assemble a monstrosity made out of multiple adapters. I suspect that the feed point deviates mainly from its theoretical position and calculated impedance because of those adapters. Seems to me, they can only have an adverse effect on the overall performance. They are far from being ideal electronic parts and they are massive compared to other components. They must leak some RF; they surely perturbate the radiation pattern and they have their own impedance.
Am I missing something?
I am sure they do. They do help to experiment though. The final version of this antenna will be soldered.
Neat job! :-)
Thanks.
You are the best teacher! Love it!🙂👍👍👍
which antenna analyzer was that?
MR-100 from Ebay, but now people use the Nano-VNA.
I am big fan of your antenna.
where did you get this sliding connector ?
+sebadtable It's a BNC adaptor, EBay.
I had rather meant this element which connecting two rods together to make antena tuned so easy
I made it with 3mm copper rods.
I live very near to a surplus radio junk place. Lima, Ohio.
Lucky man!
Salut.besoin d'aide pour fabriquer un brouilleur vhf/uhf 1kw
Heu... Non!
Merci
ok ok sorry i found the slim-jim info thank you
could i use it for harris ??
For any radio if you cut it to the correct dimensions. Keep in mind it is a mono-band antenna.
@@RadioPrepper could you make an expedient antenna for harris radio...? just an easy accessible antenna
73 😉👍
Where do you buy those bnc adapters?
EBay.
Can not forget burnt hands from playing with these
Great vid stop on
You make a lot of effort to get a low VSWR - but--WHAT ABOUT THE IMPEDANCE AT THE FEEDPOINT!!
Please elaborate... Both the SWR and impedance change as the feed-point moves up and down with the slider. Was there a question? Or are you pointing out something I did not mention?
Impedance should be 50 ohms to match the tranceiver and the coax feeder. This is just as important as VSWR but you don't mention it. Impedance will also vary with the feed point psotion as well as VSVR but the best in both cases may be at different feedpoint positions - you need to choose the best for both.
Good point in the case of this antenna which has some common mode currents running on the coax outer shield, influencing the SWR. Thanks.
Surplus from Vietnam war?
I don't know.
Pourquoi faire compliquer quand on peut faire du simple .... Tu as réussi à la faire fonctionner cette antenne? 73 de F4DNP.
Oui, et très bien :-)