All band no tuner needed antenna (This is and endfed antenna)

Started by Lamewolf, October 07, 2014, 02:02:23 pm

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Lamewolf

Guess my original post "Vertical Half Rombic" wasn't interesting enough.

Anyone here ever experimented with a Vertical Half Rombic antenna ?  Its basically and end fed antenna that is fed with a 9:1 unun on one end and has a 450 ohm non inductive resistor termination on the other end and can cover 160 thru 10 meters without a tuner and is configured like an inverted V.  Getting the materials together to build one, once I get it together and tested will post the results here.

This antenna requires no tuner for all band operation and can be setup quick in the field.  Needs only one support too - very easy to setup.

Here's a link to a pdf with info I am using to build mine: http://www.korpi.biz/hr.pdf

gil

Hello,

I did download the file. If I had the space, I would probably give it a try. Never seen one before, but again, the only antennas I have ever seen are mine  :o

Gil.

cockpitbob

Since it has a dummy load at the far end I have to wonder how much Tx power gets burned up in the load.  I love end-feds and I've heard nice things said about rhombics, but I can't get past not liking the terminating resistor.

Lamewolf

Quote from: cockpitbob on October 07, 2014, 03:29:10 pm
Since it has a dummy load at the far end I have to wonder how much Tx power gets burned up in the load.  I love end-feds and I've heard nice things said about rhombics, but I can't get past not liking the terminating resistor.


Know what you mean about the resistor, I feel the same way.  But that's why I'm building my own as I have everything except the resistor and it was delivered today.  I have the cores and can wind my own ununs and I have plenty of wire to play with.  I've worked a couple of hams on the air through the years that had them and they both had good signals but were running 100 watts too.  So I finally decided to build one to try and it will basically be for use when I operate out in the field.  Close to where I live is an 11.500 acre reclaimed strip mine that is open to the public and its basically devoid of power lines and very quiet on the HF bands.  So when I get it built, I'll setup there and give it a tryout.  The thing I do like about it is no tuner needed no matter what band I'm on ! 

And for Gil, you can make it shorter if you want to work only 40 meters and up and the wire length isn't really critical from what I've read about it.

cockpitbob

I may need to try this.  I love no-tuner antennas, or mini-tuner antennas like EFHW antennas.  And I really don't worry about the power burned in the dummy load.  Even if it eats 1/2 the power, that's less than 1 S-unit.   With CW I can work the world with 3W, so my FT-857 getting only 50W into the air is still way more power than I need.  I'm not sure I'll try it with my KX1 though.

Lamewolf

Quote from: gil on October 07, 2014, 03:06:49 pm
Hello,

I did download the file. If I had the space, I would probably give it a try. Never seen one before, but again, the only antennas I have ever seen are mine  :o

Gil.


Gil,

Here's a pdf of another version of the antenna that gives you other dimensions you can use and the efficiency figures of the various lengths you can use. You can basically make it fit your available room.

Lamewolf

Quote from: cockpitbob on October 07, 2014, 04:36:23 pm
I may need to try this.  I love no-tuner antennas, or mini-tuner antennas like EFHW antennas.  And I really don't worry about the power burned in the dummy load.  Even if it eats 1/2 the power, that's less than 1 S-unit.   With CW I can work the world with 3W, so my FT-857 getting only 50W into the air is still way more power than I need.  I'm not sure I'll try it with my KX1 though.


I plan on using it with an old Yaesu FT747GX that I have modifield as a field radio.  I have it preset to a maximum of 30 watts output and I replaced the dial lamps have been replaced with LEDs to save a little battery current and will be running on an 18aH gell cell.

gil

QuoteHere's a pdf of another version of the antenna that gives you other dimensions you can use and the efficiency figures of the various lengths you can use.


Got it, thanks!

Gil.

Lamewolf

Finally had a chance to setup the Vertical Half Rombic this weekend and check it out.  Running 5 watts SSB from my Yaesu FT-817 I was able to make several contacts on 75, 40, 20, and 17 meters - all from what some folks consider a dummy load.  On t he MFJ-259B analyzer it shows less than 2:1 on all bands except 30 meters where it shows about 2.5:1 which any autotuner would handle just fine.  But on 160, 80, 60, 40 and 20 meters the needle hardly moves off zero !  On the other bands not listed it runs about 1.5:1 to about 1.9:1 swr.  So I'm going to consider it a success and it will al go into a backpack along with my old Yaesu FT747GX that is set to 30 watts max, and an 18aH gel cell battery as a grab and go station.