diy end fed half wave antenna

project completed diy end feed half wave antenna.

I just purchased a Unun: 9:1 with 20m of wire for 80-6 meters for an old icom with an external ATU I wasn't sure whether to build one or not but decided the £44 saved myself the effort as I've 101 other things to do. Trying it this evening on 11m...... Good job.

aleksandar
49:1 ??.

yes 49:1 2xft-240-43 ferrite toroid core and 24 awg enameled wire.ceramic capaicitor 221 3KV( 2x220pf  in series 102pf)

Thought it was.
It's my plan for tomorrow to make one had it in mind for ages now but i sorted the bit's out tonight before i locked up.

9:1 vs 49:1 is the latter better for monoband or am I getting it wrong, what are the pro's con's please?

superfandango wrote:

9:1 vs 49:1 is the latter better for monoband or am I getting it wrong, what are the pro's con's please?

49:1 is usual for a efhw wires (monoband).
9:1 is more a good match for random lengths of wire (might need a tuner as well to get the match / swr good depending on length of wire used and the band to be used on).

superfandango wrote:

9:1 vs 49:1 is the latter better for monoband or am I getting it wrong, what are the pro's con's please?

The 49:1 (or 64:1) transformer is used for a end fed half-wave (EFHW), where the impedence is several thousand ohms.  A 9:1 is used for a random length long wire (Which isn't really random, but more a "not 1/4w or 1/2w on any frequency you're intending to use" length so you don't get high or low impedance the 9:1 can't match, and charts exist to show good lengths to use).

A 9:1 is multi-band in the sense it isn't resonant anywhere, and will need a good tuner to match all bands.  An EFHW is resonant on the fundamental frequency you build it for, and pretty resonant on all harmonics above, but at the expense of pattern for some bands.  It is a good compromise antenna, and I run one here, in my case built on 3 x 240-52 cores, cut for 80m and running as a horizontal wire, and used mainly for 40/80 as I also have a Cobwebb for 20m through 6m.

You could build a mono-bander, perfectly tuned for that band, which is really no different to any other 1/2w vertical other than the fact you don't have to position it vertically.  I have one of these built for 20m, but use a different core material when I'm only dealing with the higher HF frequencies.

Ahh great I got it right then as I've an Icom multiband with an external Icom ATU 
Thank you for an easily understandable explanation. Presently doing my ham course with EssexHam
All the best

superfandango wrote:

Ahh great I got it right then as I've an Icom multiband with an external Icom ATU 
Thank you for an easily understandable explanation. Presently doing my ham course with EssexHam
All the best

An AH-4 with a random length wire is also a very good compromise antenna…..and I have also used the AH-4 to run a horizontal loop with good effect too.  

Good luck with the exam.

I left this 9:1 V 49:1 unanswered last night as i was interested in other peoples answers.
As i said i will be making my 49:1 today as part of a antenna i will be trying.
I am making the "80-10  shortened" sold by UKantennas witch also uses a 49:1
Got a 80-10 with a 9:1 but took it down when i put the 7 band cobweb up mistake lol not the cobweb but taking the long wire down.
Station commander not too happy that the wire is going back up but it is and bit extra lol.

Are you following this with a line isolator/ choke balun? I understand they should be inserted .05 wavelength from the feed point. Also how much power will a single toroid cope with before it gets hot...

I treated myself to a sirio sd 27 halfwave dipole for at my mum's. Very very impressed with the quality of it. Good antenna

rfburns wrote:

Are you following this with a line isolator/ choke balun? I understand they should be inserted .05 wavelength from the feed point. Also how much power will a single toroid cope with before it gets hot...

Yes, mine is choked just back from the transformer, which is my case is basically mast height as I have a lightning arrestor and choke there before it picks up the LDF450 back to the shack.

Typically, a 140 size torroid will do 100w SSB at normal duty cycles just fine, but digital modes and possibly CW will need a bigger, or multiple cores.

The choke on mine is at the end well about a 1mtr in and that last 1mtr is folded back to tune for 80m band.
It might be more that 1mtr in fact i think it is 2 and a bit but my notes are in the shack not here with me.
Not looked yet this morning if i still have it up lol a bit windy on the coast here blown a wooden sun lounger down the garden that i can see and a panel out of the greenhouse.