T2LT/Coax Dipole CB/11m/Ham Antenna - Alternative 2-Piece Build Method/FAQ's
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- เผยแพร่เมื่อ 11 ก.ย. 2024
- A long video with lots of chat/info, but you don't have to watch it all - links to sections below:
Overview/Explanation 2:55
Pre-Construction Prep: 10:51
Construction: 12:29
FAQ's: 27:05
Deployment/SWR Test: 44:19
DX Contact (2014): 46:32
Epilogue: 47:45
Answering a build question that's been many times asked since my original build videos in 2013 and 2014, plus a section on other FAQ's that I've been asked over the years.
Links:
2014 Video Part One: (Single Piece Design plus Theory) • Cheap and simple T2LT/...
2014 Video Part Two: (SWR Testing) • (PART TWO) Cheap/easy ...
Imperial/Metric Conversion: www.worldwideme...
Steve G3TXQ (R.I.P) Choke Chart: karinya.net/g3t...
A long video with lots of chat/info, but you don't have to watch it all - links to sections below:
Overview/Explanation 2:55
Pre-Construction Prep: 10:51
Construction: 12:29
FAQ's: 27:05
Deployment/SWR Test: 44:19
DX Contact (2014): 46:32
Epilogue: 47:45
I made a T2LT based on your video instructions, it has given me over a year of perfect service on 11 meters.
Good to hear - for me, they've been so reliable, I'd not made one for years before the one in this video. I've had them deployed in terrible weather on hilltops and used a couple as base antennas too. Cheers.
OUTSTANDING video. I'm making one of these tomorrow for my Anytone 6666. I have seen this antenna cut to handle 11 and 10 meter with little to no adjustment. Thank you sir.
I've used nothing else for years now - just pick the optimum choke dimensions from the G3TXQ chart for the chosen band and all should be well. Cheers.
I have a Hawkins version. Works great!
1/2 wave an d 5/8. Swr is spot on and pretuned.
The easy way to do it when you have arthritis and can’t use your hands!👍
Absolutely - make one if you can but, if you can't, there's the commercially available ones on eBay etc. Cheers.
Do you have the specs for the 5/8 type from 416 Trinidad 73s.
@@alvinpope9315 - Hi Alvin. I've never tried to make one myself but search "Wire Gainmaster" and it seems some others have tried (like this one) radioaficion.com/cms/sirio-gain-master-homebrew/
@@ukcbtv i had wondered about the matching stub, saw another couple of videos building these but the tuning stub was not clear, the link here has GOOD instructions, thanks
@@alvinpope9315 look at Mike m0msn video on you tube
Thanks Gary. Interesting video again. Can I just say thanks for the time you take to answer the points that your viewers make. Questions are answered regularly too. Not all video makers bother to answer their viewers questions/points.
Thanks Mark - I try to answer as many as I can! Cheers.
Gary, thanks for the shout out towards the end. I found that the "alternative" choke (16 turns around 68mm) has a slightly wider 1.5:1 swr curve on the 10m version (so same for 11). I plan to do a quick test to see if there is any difference performance wise (minimal if any maybe), although the narrower curve with the 5 turn choke version lends me to suspect a slightly greater efficiency (higher Q). Marginal though I think. These antennas work - with the choke 2m off the ground and 100w I managed to work S America and Caribbean last year from home. Also great as you say for hill-topping. Re: chokes - the commercially built ones for the amateur bands which are sold on ebay tend to use the same choke design (24 turns around 68mm former) across different bands.That leads me to suspect that the G3TXQ chart which, as you say gives varying choke sizes for each band must be of greater accuracy for required impedance. 73
Yeap, that works just as well as the bigger choke.
Hi Tim - no worries about the shout-out (always good to see the word being spread about this excellent antenna!).
Regarding the chokes, I've found the G3GXQ chart to be spot on and the 5 -turn version has been so good for my area of interest, I've never had to deviate from that. Always worth keeping watch for a hot feedline with this and other designs though especially on the higher power installs - you know, SWR variation when the coax on the radio side is moved, metal casings touched and mic leads grabbed (or hum on TX), amps holding on etc. Cheers.
Works great! Made one up last night exactly the same way and working perfectly with SWR of 1.3
Good to hear of a successful build 👍
Those aerials work well, if it does not work, you have done something wrong. Choke can be a bit funny but if that one does not work have a look at Tim's comment below, both chokes work, so if you find one does not work try the other. It does work, I made one years ago.
I made a dipole years ago with 102 inches each way and I just had a few coils wrapped round as a choke and it was 1.5-1 SWR at each end and I got most of Europe on it and further afield. Only used 4 watts (if that) and legal UK channels (referred to as the muppets) at the time.
I do not see any reason why we can't use the whole of 27Mhz from 27.000 to 27.999. Though we have to respect the old channels for the UK until all the 27/81 sets conk out.
That might take a number of years yet.
Good video. The part of the cable that you use for the excited element should be at least 1.5 millimeters thick, since the thicker it is, the greater the bandwidth. greetings from XE1KW.
True, but will make the antenna more bulky for portable use. Regards.
The point is you made it and it works as intended .I copied your instructions and worked a treat never mind about all the hatters good job 👍
Good to hear it's working well for you! Cheers.
T2LT the only antenna I've had a contact to New Caledonia & OZ on 11m brilliant antenna. Thanks to you and Roy Corsica for bringing it to me back in the day. 108CV001 (108CTX1642)
The thing is almost too good to be true - made my portable ops so much more easy (I used to drag a Silver Rod and a mast up the hills!). Cheers.
Yes a very underrated antenna I have 2
Great video, very informative and learning new things all the time ,proper job
Cheers Chris 👍
I tried one of these in an inverted V shape and a normal L shape in my loft before I put an outside antenna up.
Not ideal but it did work and the SWR was much better than it is on the commercially sold ‘loft’ antennas or the Magmount on a biscuit tin.
Versatile and easily deployable.
Nice video. 73 Franco
Been using these for over a decade now and they just work well, especially for the portable stuff I do. Cheers.
I made one yesterday after watching your video with great results. A disabled friend have mine has been ordered to take his Antron down by the council which I think is cruel, so I’m taking him this tomorrow so he can try it in his loft or the garden.
Thanks again 👍🏼
Definitely the best videos I saw.
I would like to make QSO with you on Ham bands
The 110mm former ... you can actually buy an end cap for that size soil pipe, and you can wind the coax on the inside of the cap as apposed to the outside the pipe!!
Offers excellent protection! Also I've used a hot glue gun to secure the coil when constructing the coil.
Good idea and great to see others adapting and improving on the design 👍
@@ukcbtv you can drill an "out" hole in the end cap for the bottom end of the "bottom end" of the dipole vertical, and even drill a hole through the 'soil pipe end cap' to secure it to the base of the mast (or tree) but definitely a hot glue gun is a must.
Made one today, quick test with a friend about a mile away, and he was receiving perfectly on his cars mobile antenna but was a bit quiet and patchy talking back to me
A easy permanent base station version could be a PVC pipe shield enclosure section and a standard 103" whip mounted at the top instead of your flexible wire extension. But wouldn't any other CB whip work as well in a pinch to a lesser degree at the top, say a four foot mobile whip?
You're right, any whip long enough would work. I made the top part of 5mm ø aluminium tubing which I put on top of my 9 meter tall military fiber glass mast.
Great job. Thanks for posting this.
For a choke, would a RU-1:1 Unun made by LDG work?
From LDG's Balun and unun document,,,,The RU-1:1 is a 1:1 Unun intended to help remove unwanted RF from the
coax cable shield. It is normally used as a common-mode RF choke for short
coax cable runs or non-resonant antennas. The RU-1:1 features SO-239
sockets for both input and output.
Thank you for your time to explain on construction.
Great video Gary. My only query is your measurements. You did not not include the velocity factor of the coax when calculating the length of the di-pole. The antenna length will be slightly shorter than your own figures. This would help with the SWR and make it lower.
Hi Keith - I've seen this discussed on the 'net and the general synopsis is that the coax V.P is no longer applicable once it's stripped back and turned into a dipole with the outer skin of the braid becoming the lower element. As for SWR, the reading at the centre frequency, and the SWR curve, is what would be expected of a 'standard' centre-fed dipole which has a characteristic feedpoint impedance of around 70ohms. I have made bazooka/flowerpot designs that take V.P in to account and they've displayed the same SWR curve and work no noticeably better, or worse, than this simpler design.
I mentioned V.P/V.F in this 2-piece design video in case a top section of wire is used that has significantly different characteristics than a regular insulated copper conductor (say aluminium or CCA).
Cheers.
i mean you could just build the antenna out of one cable to not risk contact resistance at the
soldered point.
That's my preferred method, but many have commented on making it this way, so I did this "alternative build" video. Cheers.
Great video Gary very useful keep them coming. Reg 29vlf2 in dublin
Cheers Reg - I'll be on one of these antennas when I go up the hills.
Is there a difference between a t2lt out of one piece of coax or with a top section of wire? And what’s is happend if I choose a thicker piece of wire for the top section.
Hi - I find the one piece version a little bit less likely to break when using it repeatedly for portable operations. I have made two piece ones with no problems though and it's mainly a matter of preference. Some types of wire aren't as good conductors as others (aluminium and CCA (copper clad aluminium)), so using these may mean some extra SWR tuning is required. A copper conductor should be fine though and a thicker one may offer some extra bandwidth i.e. the antenna may cover more channels. Not tried it myself though. Cheers.
I use 300 ÷ (the frequency you want to use in mhz) = wavelength in meters...
Hola amigo, es posible hacer esta antena(T2TL) en 5/8?.Un saludo
Sí, pero necesitará una forma de coincidir porque la impedancia será alta. Mire el diseño de Sirio Gainmaster 5/8 (algunos lo han hecho en TH-cam). Saludos
Hi Garry,what is the choke diameter in cm?
Regards
Inside diameter of the choke is 11cm - i.e the coax is wound around a former with an outside diameter of 11cm.
Thank you VERY MUCH !!!
No problem Olivier 👍
Why if you have the exact meters recalc it in feet? Boggles my mind. You can take a measuring tape and go with meters or cm or mm, it is all there!
That's the UK - we transition between metric and imperial measurements, and back again, all the time!
Thanks very muchsssssssssssss! 😎👍
Which antenna did you think is better, the T2LT or the Vertical Bazzoka with the braid folded back?
I favour the T2LT - I have noticed no difference in performance between the two and the T2LT is easier to make and a little bit lighter, flexible and tougher for the portable operations. Regards.
@@ukcbtv thankyou
Great video! I just ordered the materials to build a couple of these. I was curious about the power handling of rg58 coax so, I looked it up. I'm not 100% on the choke but, I seriously doubt I'll be putting 500w through this antenna!
How many watts will RG58 handle?
RG stands for "Radio Guide" and is a military term. The 58 class has an outer diameter of 0.195 inches, 50 to 53.5 ohms impedance, and can handle up to 500 watts of HF (High Frequency) power.
If anybody has tried running power through this antenna, I would appreciate if you could let me know how much power and the effect on swr, heat and, so on please.
Good luck with the build! As far as power handing is concerned, probably the limiting factors will be the choke heating up as it blocks common mode current and also RF leakage past the choke - a.k.a 'hot feeder' (it's a simple antenna that can be constructed 'in the field' with basic choke design intended for low power/portable/emergency operations and will not be 100% efficient at blocking RF feedback). Most I've heard that anyone has put through it is 100w - some may say higher but they're probably hiding behind a tuner with RF grounding. Cheers.
@@ukcbtvI built the one piece version Saturday. It's my 1st and, it turned out really good. SWR was 1.2 on Ch.1 and on 19 and 40 (U.S. 40) as well. It will probably change whenever it's properly set up outdoors. I had it laying across my kitchen when I tested it.
The T2LT is considered an electrically center fed dipole, correct? If so, when in the vertical configuration, would the height above ground be measured at the choke or, at the midpoint where the braid ends and the bare dielectric begins?
Hi Gary, can you explain why you used a fiberglass pole and said "no carbon" cheers, pete.
Hi Pete - carbon is a conductor of electricity (albeit not a very good one), so has the potential to throw the antenna out as far as tuning and performance - generally the advice is to stick to fibreglass. Cheers.
@@ukcbtv thanks Gary, hope your all keeping well over there
Is that TL2T available in the U.S.???
Hi Eric - a search on eBay US shows one for sale (shipped from UK).
Will these work horizontally thanks
Being electrically a dipole, it should - might need to play around with the SWR tuning a bit though. Cheers.
Hi what's a good height for this antenna 73s from 416 Trinidad.
The old timers will say 18ft (1/2 wave) to the base for summer sporadic E skip shooting and 36ft (full wave) to the base for the long F-layer skip. Height is always might for the groundwave stuff. Cheers.
@@ukcbtv thank well its 36feet for me 73s.
Bro! Step up to the mic already!
Don't just ramble on while walking away or turning your head from the mic...Makes you fade out.
:)
Nice little walk through on these easy made 1/2 waves though. {edit...I said 1/4 wave. :P }
Thx for the vid!
Q: If using RG8, is the choke length (about) the same?
Reason being is that since thicker, the wire and insulator would be further away from the 4.5" pipe.
I imagine it wouldn't knock SWR off much but I don't know.
If so, adjust by wind/unwinding a bit at a time?
Hi. I've only made them from RG58 but, looking at the G3TXQ chart, a thicker RG213 still has the best choke performance with a 5 turn / 4.25 inch former, so worth trying that size as a starting point for other coax cables - the only data I've used for chokes is from this chart karinya.net/g3txq/chokes/
Do you know if this can be made with lmr400? I have about 30ft sitting under my bench
I am from Indiana hi love it will you make those antennas I tried it didn’t do very good but I’m gonna keep trying. Try to get it right I like using 27.385 MHz 38 upper sideband radio channel that’s what I like talking on. I like to get one just for that I’m trying to make a gold bag radio there’s not too many go bags radio called Indiana learned to grow bags or ham radios not for lemon metres radios but I’m trying to get people involved in that but we can have contact teach others that way but I am trying to make one of your antennas. I think you’re very good at it I enjoy listen do you and I enjoy your channel song if nothing spelled right I can’t spell very good.
Keep at it - it'll come together in the end! All the best.
Could you use a 1.1 balun instead of ugly balun?
Not something I've experience with, but perhaps a 1:1 common mode choke/line isolator would be worth a try instead of the ugly balun - something like this perhaps? th-cam.com/video/SMtFhZoq9rA/w-d-xo.html
@@ukcbtv Yes that's the type.
@@paulhotson5820 - well worth a try as it should do the same job as the coax choke.
I made one like this did western union joint graet vedio as all ways
Did you build your shede it looks NICE
Thanks Joe 👍
Shed is great - I could live in it to be honest! (we did buy it about twenty years back, so can't claim to have made it ourselves). Hope the goats are going Ok. Cheers.
@@ukcbtv I got 31 baby goats this kidding season n 2 caves n next mouth I sart 6 new bee hive
@@joerowland7350 - nice Joe, sounds like a great setup you've got over there!
never depend on a mechanical connection
Great video; very informative. I'll be having a go at this very shortly 73 EJG23
Thanks - good luck with the build!
73+++++51