One of the Best Ham Radio QRP End fed half wave (EFHW) antennas available

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The antenna is designed - with its 21 metre length radiating element, to operate on 40M, 20M, 15M and 10M with a resonant point SWR of less than 1.5:1
At the time of this video preparation, 40m 20m (and 17m) were ‘Up’ but 15m and 10m were ‘Down’ with almost no received signals showing on either band.
(I will investigate 15M and 10M performance in another video when ‘conditions’ have normalised!)
This EFHW is excellent value:
- Buy or build the 64:1 UnUn for circa £30
- Buy 2 wire-winders for £5
- Buy a 6m or longer mast for between £20 and £50
- Buy some antenna ‘wire’ for the radiating element £5
- Buy some 3mm Para-cord for 'guy ropes' £5
The End Fed Half-wave Antenna has a lot to offer.
It is inexpensive, it is rather efficient (thanks to having a half-wave of wire -- with no loading coils -- in the air) and it is easy to put up - either with a portable mast, from a tree limb, or suspended from a window -- vertically or as a ‘sloper.'
In a previous video, I showed how to install this antenna for portable operation with a 6 metre fibreglass pole and a 4 tent pegs. (3 for the mast guys and 1 for the far end of the antenna.)
The ‘exciter’ used to test the antenna was my trusty KX2 with an external home brew LifePo4 10Ah battery pack.
The transmission mode used for this test was WSPR (pronounced ‘Whisper’)
WSPR is an excellent transmission mode for reporting connections you have made around the world using the wsprnet.org/ website.
If you run ‘Digital Modes’ using WSJT-X then you are all set up to run WSPR. Simply select it under the ‘MODE’ section of the top ribbon of WSJT-X (It’s in the third drop down pane) and read the Help file to get to know how to use it.
My conclusion: "This antenna is truly one of the best portable wire antennas I have used."

Пікірлер: 9

@bigphil6980 Жыл бұрын

hi Dr T did you do a build video so others can follow how you make there own antenna as i would love to build my own copy but have never built an antenna before as i have purchased my antennas before but would love to make my very own antenna and any alternative for the 64:1 UnUn for circa in case the one you use is not available to buy cheers Phil 2E0FJQ

@G4ABX Жыл бұрын

Phil. I've not done a build video -- yet but let me consider that for a future video. I need to chat with Colin who made the UnUn I'm using so lets see what we can come up with. I'll get back to you early next week 73 Bruce G4ABX @G4ABX

@Capt_Duffy Жыл бұрын

very nice video.... I'm having an issue with my EFHW 64:1 (homebrew) 40m is 1:1, 20m is 1.5:1 , 15m is 3:1 and 10m is also 2:1, why im having high swr on 15 and 10m Band, antenna configuration is Inv L ....thanx

@G4ABX Жыл бұрын

Hmm. Interesting problem! Can you tell me where on the higher bands the SWR is lowest (i.e. above 21Mhz, above 28Mhz)? and what is the lowest level of SWR for these regions? I might then be able to offer some advice :-) 73

@Capt_Duffy Жыл бұрын

@@G4ABX thanx alot Sir, on 15m its flat all across 3:1 and on 28 its almost flat as well, its 2.7:1 at the start and 2.8:1 in the end min is 2.4:1 at 28540 khz, just for i didn't have the 100pf capacitor, so i joined two high voltage 220pf capacitors in series to get 110pf capacitance.....thanx

@G4ABX Жыл бұрын

Good morning. When developing the UnUn, a 49:1 ratio was tried -- but it turned out the SWR was Ok on the higher bands but not on 40M and 20M. The 64:1 ratio cured this problem. Its also critical that you use the correct ferrite otherwise you will have too little -- or too much inductance for your chosen bands. Finally, its important that you 'twist together' you primary and secondary windings for the length of the first winding -- when you start and you are winding the coupled primary/secondary. Your 120pf Cap should be fine, that's not the issue. Does any of this point help trouble shoot your issue? 73 Bruce G4ABX

@Capt_Duffy Жыл бұрын

thanx alot Sir for the detailed reply, actually i read somewhere that winding without a crossover with a tap after the 3 rd turn for 64:1 unun (3 primary and 21 secondary) is more efficient (not sure if its right or wrong) so i unwounded my previous unun which was working fine, and did it again without crossover, 40 and 20m were fine but no matter what i do higher bands were not coming down 3:1, so again I unwound it and again wounded in the traditional primary winding twisted and a crossover with the same 3 turns primary and 21 turns secondary, and now its again working fine, so i have decided not do any more experimentation and just stick with the traditional winding.... pattern....thanx alot

@G4ABX Жыл бұрын

As my old Dad used to say 'The Better is the enemy of the Good' as I rebuilt my RX for an extra 3db gain and broke something else on my way! 73 Bruce G4ABX