#347
ฝัง
- เผยแพร่เมื่อ 11 ก.พ. 2022
- This is a followup video to #344 where I assembled the 49:1 UNUN kit from HF-Kits / ARRL. Here I show finalizing the antenna, getting it in the air, and running an SWR sweep on it. Here is a link to the 49:1 kit I used:
• #344: ARRL 49:1 End Fe... - วิทยาศาสตร์และเทคโนโลยี
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I’m about to head out today to try and cut a wire for 20M to use with a “Sparkplug” 49:1 transformer. Your video encouragement arrived in a timely manner.
I have one of them too, I haven't tried it yet. Love to hear how well yours works!
I hear FT92 cores work well with those masts that are made from a giant french fry.
Thanks for the video.
I bought the same kit from ARRL for Field Day 2021. I was very pleased with the result. I got acceptable performance on 40M, 30M, 20M, 15M, 12M and the lower part of 10M after trimming it using a nanoVNA. (I mainly use FT8, so mostly live at the lower parts of all these bands). I later replaced the wire with one ~132' long and added 80M. The only issue I have seen is that I get a LOT of RF feeding back into the shack around 20M. I may try adding a counterpoise.
Was a good day to work outside for sure. Was in Princeton last night for the NJARC meeting. Worked in the repair lair today where it's still cold enough to chill beer!
Another great video! I like them all - they clarify what past instructors couldn’t! A lot of your videos have inspired me to learn, experiment, repair things I wouldn’t have otherwise. I would like to see the follow on topics you suggested for this antenna and 1:49 unun . There seem to be many variations on the wire lengths some with coils. It would be great to see how those work with your instrumentation to visualize it and your knowledge to explain it. Thanks so much for all your videos!
Great video and "thank you" for doing this, Alan! -73 KQ4KIO
Thanks. Appreciated your video.
Put out 3 radial wires for my vertical HF antenna. Wind chill 32 deg F. Enjoyed the time outside. NOQFT
Your landscaping and pavers are impressive. 73 from Daytona Beach
Thank you - we had a great contractor that really took pride in his work.
Received the HF Kit of the EFHW Antenna this week. Perfect timing!
Assembled mine yesterday. High quality kit and first trial went well. Will need to optimize the counterpoise.
nice writeup.. thanks for sharing
Good to take advantage of an unusually warm day and see how the antenna project turned out. Looks like it should do well. I am using a 53' EFLW at 11ft. AGL with fairly good results but have been curious to try an End Fed Half Wave to see if it is better or worse. 73!
Looks like you just beat the snow we are now having!
Yep - the backyard now has 2-3" or so now, still snowing.
Well done Alan, don't forget you are measuring the entire system in your case, really you should measure right at the transformer. If you put a resistive load where your antenna should be you can fine tune the secondary impedance a little to show 50r or there abouts at both ends of the expected impedance say 2.5 -4.5kr.
Yes, or course. At the end of the day, I'm interested in measuring the system, so that I can see what the transmitter sees from an impedance standpoint.
I have 75m dipole woven between my rafters and roof decking. It's resonant at 3.916 but tunes 160m to 6m Some (2 if I remember right) bands are unusable because of RF in the shack. I've done some things to improve it, like a 4:1 Balun and 1:1 Choke. I use it for CW, FT8, and SSB DX. My log is mostly full of FT8 these days (I made it into QST this month :) ). By all accounts it shouldn't work, but it does.
Sir, I request to you that please write a book on your practical experiments in electronics. God bless you and your family. Jawaid.
I've been asked that a lot. Maybe when I retire... ...no time to do that now.
@@w2aew Sir, thanks for your reply and God Bless you. Jawaid Mughal from Karachi Pakistan (Member of Pakistan Amateur Radio Society).
What? NO SNOW? Looks like a great antenna project! I swear that it seems like wire antennas outperform beams at times. I especially like the idea of the pulley at the top of a mast to make quick changes and comparisons. I've been getting back into CW myself. Keep us posted with some on the air test results. Thanks Alan and 73's.
Certainly on the lower bands (below 20m), wires can work better because they don't have to be "shortened" with loading coils, etc. The pulley at the top of the old sailboat mast is really helpful for experimenting.
I have a center fed dipole fed with 300 ohm twin lead through the window. It consists of about 65' of twin lead, and two 65' 14 gauge wires coming off the center fed point which is only about 15' off the ground. The ends actually go into the snowbanks (I live in Maine). I copied the idea from my 1955 HB. 10 meters has been wide open and this antenna seems to work good all the way to 80 meters with no gaps to speak of using a Murch UT-2000a tuner. My first contact was a 15 meter ssb to a PA station running who was running QRP. I like to tune my antenna using >2 watts AM with no audio. I forgot to turn the power back up and we exchanged 59 signal reports!
@@W1RMD Very similar here. I use a 130' center fed dipole, but with the 450ohm window line, going through the window to my 2nd floor shack. I use a Ten Tec 238C tuner, operate from 80 to 10m - mainly on 40m and 17m for me.
OMG! Tell us all about this “outside” world please! lol jk thanks again for yet, another great video. 73
LOL! I actually *do* spend a lot of time outside, but just don't make many videos outside ;-)
@@w2aew lol I thought you’d get a kick out of my comment. Thanks!
🌟
❤️👍
I just purchased a 7510-2K myantenna EFHW antenna for my first HF phone rig. Your video helps and gives me a reason to buy a rigexpert AA-230 for HF and 2m.
Does anyone recommend the rigexpert AA-230 instead of the NanoVNA? I think the NanoNVA requires calibration every time you switch bands? 73 to all !
Great video as usual, Alan. Could you someday cover why you considered a common-mode choke and why one would need one (and how to make it)? Thanks!
An end-fed halfwave has an unbalanced feedpoint. Usually the coax shield provides the counterpoise, and thus may require a common-mode choke to keep the shield current from potentially causing issues at the radio.
@@w2aew Thanks!
Nice Alan. I am trying to get my CW chops up but life happens... I would have to listen on SDR. S9 noise floor here...let me know when you are on.
Most of my operating time is on 40m CW, between 0000Z and 0400Z (8PM-midnight here in NJ).
@@w2aew are you qrp?
@@-Todays-Tom-Sawyer- When operating portable or on vacation - yes. When operating from the home shack - sometimes. I usually run 25W CW from home, but occasionally will run
👍🙏🙏🙏👍
Very good. What size and type of antenna wire do you recommend? Should I be worrying about hurting birds? --Joe W2JEJ
Hi Joe - No worries on hurting any birds - it's unlikely they'd be in a position to bridge themselves between the high-voltage ends of the wire and ground. I just used the wire it came with - looks like 16 or 18 AWG with a tough UV resistant jacket.
grrrr he has a turner behind him... someday ill find one ... works great on my HK 110a ...
I run that old +2 on my TS-830S.
@@w2aew i tried a d104 old school and the newer black and gold soild state d104. nite eagle i think its called.. there ok.. them old turners just sound good.. matchs the heathkit setup. hahha
@@XPFTP The D104 you see in the picture is used with my TS-870S - but it has a little secret. The original transistorized preamp is removed and replaced with a homemade preamp and tone-control circuit.
@@w2aew that is something they needed bad. tone control.. maybe this summer ill tinker with one of the d104s.
Have you ever made a video which mentions winding RF transformers or inductors with a coaxial cable ?
Unfortunately, no.
Looks like there are great losses somewhere in the transformer and feeder. I guess the EFHW antenna has to have a more steep VSWR curve. Maybe I'm wrong or missed something, but my own practice and modeling experience say the opposite.
I suspect a good part of it are ground losses given how close this antenna is to the ground.
does changing the antenna from a straight line to say a shallow v shape change the effectiveness of the reception?
More height is generally better. Going to a shallow V shape will make the radiation/reception pattern slightly more omnidirectional.
Are those yard lights your beverage antenna ;)
They do often accompany a *beverage* of some type...
@@w2aew Dang my next trips were going to be out west & Florida , now have to NJ for beer ;) & BBQ
Why did you not test it on 20 , 15 and 10 meter. great thing about the endfed halfwave is that it is resonant on every even en odd harmonic, no tuner required.
Yeah, I should've tested at the higher harmonics too. In my head I was just thinking about my mono-band 40m CW transceiver (QRP Labs QCX+), so my testing was focused on that use case.
Excuse my ignorance as I’m still learning, is there a way you can tap of the main antenna cable with a moving connection and moving it along until you find the sweet spot. Thanks 73
I'm not sure what you're asking. What sweet spot are you looking for?
@@w2aew The point on the antenna length that gives you optimal reception and the best reading on your analyzer. Considering you have extra cable twisted at the end.
@@richardshort4587 It's not really about finding the correct point to feed the antenna, but rather adjusting the overall length of the antenna for best efficiency (in this case) An End-Fed Half-wave is called this because it is a half-wavelength long at the desired operating frequency. Same thing for a simple dipole. There is another type of antenna called an off-center fed dipole where there is a feedpoint that is between the end and the middle, but that's not the antenna we're talking about here.
@@w2aew Thanks for the explanation. 👍🍻
Sorry about a rookie question, new ham here. Does it work the same way if this hangs down from a 5th floor apartment window?
The problem with hanging the wire out of a window is that the wire is very close to the wall of the building. Any antenna, including this one, will be affected by nearby objects. So, both the tuning and the performance will be negatively impacted.
@@w2aew I see. Thank you for the reply.
Should this work on 17 and 30m as well?
Probably not with the same wire length
Was there any counterpoise at all?
Just the shield of the coax.
Thanks for another great video. I have been curious on the effects of simply pulling the wirres back is versus trimming. I watched a video that stated the capacitance went up if the wires were too long. I suppose that makes sense if they are not twisted. I've often wondered if you pulled the wire back then finding a point about in the middle to twist the wire around but in opposite directions on either side of middle would make a difference. If you were going to play with the choke more there was a video by Steve Ellington on using the coax as counter poise. The link shared is is a summary of a much longer video that he did. I thought it might give you some ideas of different things to test or how to do the test differently. th-cam.com/video/MzfQybYMlUc/w-d-xo.html. Thanks again de ki7cia.
Thanks, I"ll give that video a look see...
HEIGHT makes the difference....
can it work 5,000 miles under dead band conditions with about 5/8 watt?
My 20m dipole did last nite. Italy 5-8.
No chance on that junk end fed.
No such thing as end fed HALF WAVE.
Efs are RANDOM LENGTH WIRES according to a reputable source ( not internet rumour) Radio Antenna Handbook 1935, published by Engineers at Radio Magazine.
Do an amateur radio basics tutorial
Oooh, there are so many topics that could be covered... ...where to start?
@@w2aew you can make an entire series/playlist. like what is ham radio, then you can make videos about the basic equipment necessary to start the hobby, review/tutorial of ham-related equipment and so on. yes, there are similar videos out there but your basic videos about SA,NA, oscilloscope are most watched -because you are a very good teacher.
@@EEEAmin I can add that to my long list of potential future topics.
49:1 means transform from 50 ohms DOWN to about ONE OHM.
That means the antenna is a DEAD SHORT AND CANNOT WORK.
You mean 1: 49
Gross ignorance pretending to teach others is how ham radio became the Blind leading the Lame.
It is 49:1 from the antenna's perspective, and 1:49 from the transmitter/feedline's perspective.
It's a real shame that you feel that 42 years as a ham, and 39 years as a gainfully employed electrical engineer doing analog/RF design, test and validation, still makes me grossly ignorant. It must be very lonely in your ivory tower.
K8BYP you are the one that shows great technical ignorance yet once again. You knock others in almost every video you make as well as when commenting in the videos of others and it appears you have an inferiority complex. You also block others that post actual data in a constructive manner showing that many of your technical statements are in error. W2AEW is one of the most competent engineers and youtube video creators that exists, and you have once again shown your technical ignorance and overall poor social behavior.