HF Antennas= Dipole, OCF Dipole / Windom, etc.

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seangt

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So I need a better HF antenna. My Eagle1 vertical isn't cutting it. It's a 30ish foot piece of wire in a fiberglass tube. The radials didn't seem to help. Something may be wrong but my best SWR of 4 on 80 meters won't cut it even with the tuner. It will get down to 1.5 on 40 meters but is pretty bad everywhere else.

So it's time for some wire and I've got a few questions.
If I can hide it I've got room in the yard and a few trees. Leaning toward an 80 meter Off Center Fed Dipole to match my yard and what others seem to have had luck with.

I've got an LDG 4:1 Unun that came with the Eagle1. (1.) Might work?

The Balun Designs 4116ocf has been highly recommended. It's got voltage and current baluns inside. Probably my prime path right now.
But.. there's the 4125 which has only the voltage balun. That allows current on the feedline where you put a current balun in a certain spot a few feet down to create a Carolina Windom. The vertical part is suppose to help with close contacts.
(2.) So 4116 or 4125 to use the feedline and have the Carolina version?


Coax. I need to get about 100 feet out there to attach to the feed point. (3.) RG8 enough? I'd like to save the piece of LMR400 I have for 2 meters.
 
Check out this thread: https://www.carolinafirearmsforum.c...ns/11812-finally-getting-my-hf-stuff-together

I am far from expert on this matter, but I don't think you want the feed line radiating if you have a properly designed dipole, in which case it's not necessary.

I am am getting ready to put up the one I linked to, possibly this weekend and I bought some LMR400. It was cheaper then RG8. I also think that your more likely to be working with small signals on HF then on 2M meaning the losses will effect you more. As the saying goes, if you can't hear it, you can't work it.
 
My advice: Don't over analyze. Put some wire up and make contacts using whatever coax you have at hand.

There's a lot of problems that exist on paper that aren't actual issues in practice.... particularly at HF @ 100 w or less.
 
JohnFreeman;n97363 said:
My advice: Don't over analyze. Put some wire up and make contacts using whatever coax you have at hand.
Click to expand...

This is worth repeating.
 
seangt;n97247 said:
I've got an LDG 4:1 Unun that came with the Eagle1. (1.) Might work?
Click to expand...

I have a LDG 4:1 balun that came as a gift with a tuner. I made it into a 80-6M OCF using zip cord. I used to carry that to use with my FT-817ND portable. It worked great. Use that balun, whatever coax you have and any miscellaneous wire and it will be better than an Eagle vertical for your current need.
 
What kind of tuner and rig you have?

i run a G5RV and my LDG tuner on my ICOM 706 has no issue tuning it but my TS2000 internal tuner did.

it cover 10-160. I use mine mostly on 40 and it's 38ish feet in the air at its highest point and 30ish at its lowest.
 
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seangt;n97247 said:
The Balun Designs 4116ocf has been highly recommended. It's got voltage and current baluns inside. Probably my prime path right now.
But.. there's the 4125 which has only the voltage balun. That allows current on the feedline where you put a current balun in a certain spot a few feet down to create a Carolina Windom. The vertical part is suppose to help with close contacts.
Click to expand...

Everyone that has used the OCF formula that I followed (Howard is the man) has RAVED about how well it works. Mine has ZERO problems talking to JohnFreeman who is about 10 miles away and trcubed who is about 20-25 away. Close contacts are no problem it seems (mine is at about 25' and flat top, Howard and Brian are inv V...seems to make no difference) for all of us.

All that said I can get out to Oregon with a great report as well. 80mOCF for the win.
 
One of the LEAST limiting factor in a new ham making contacts is relative coax cable loss :). Things like forgetting you have RIT on, or transmitting in USB instead of LSB, transmitting into the dummy load, wrong antenna, using the wrong band for the time of day, lack of proper procedure, misadjusted transmitter...all of these things (many of which I still do more than I want to admit) are much more likely to be stumbling blocks before a db or so of cable loss becomes a gating issue to ham fun.

Radio is pretty forgiving. If your feedline is in fact radiating... it's radiating RF. The same RF you want radiating off your antenna element.... it's going into the ether. Yes, some if it is turned into heat in the trips up and down the coax, but MOST of it is being radiated.

Don't worry, be happy, make contacts, optimize as you go! :)

Better RG58 in the air, than hardline in the catalog!
 
JohnFreeman;n97917 said:
One of the LEAST limiting factor in a new ham making contacts is relative coax cable loss :).
Click to expand...

Coax loss being variable depending on coax type and frequency, at HF frequencies coax loss is of no real concern. Your loss concerns will be more important when you get to VHF/UHF. I use RG-213 and 9913 for my HF antennas, RG8X for mobile and LMR400 for my VHF/UHF, but when portable I use RG-316 (or RG-174).
 

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htperry;n97936 said:
Coax loss being variable depending on coax type and frequency, at HF frequencies coax loss is of no real concern. Your loss concerns will be more important when you get to VHF/UHF. I use RG-213 and 9913 for my HF antennas and LMR400 for my VHF/UHF, but when packing, I use RG-316 (RG-174 equiv).

Click to expand...
 
ANY edition of the ARRL antenna books are great. Buy one, and you're really good for life (there's very few "new" antennas). ^^ They're a great value.


Re: coax....if you've got the time and the money, buy the best, but tens of thousands of hams make millions of contacts on RG58 on HF before someone told them it was no good. That's a nice chart Howard... and you can see the diff at 10Mhz between 8x and 9913 is a numerical amount that is almost indistinguishable unless one is operating at very marginal conditions.

At VHF and above, the situation is quite different and the losses become more dramatic, no question... but if you have a short run to make (15-20 feet) there's little difference other than on paper, and man....is smaller coax easier to plumb in the shack!

My point (particularly to beginners) is... get what you can get and get on the air. You'll make thousands of HF contacts before you discover moderately priced coax is no good :)

(and if you want really low loss, run open line!)
 
JohnFreeman;n98113 said:
ANY edition of the ARRL antenna books are great. Buy one, and you're really good for life (there's very few "new" antennas). ^^ They're a great value.
Click to expand...

No doubt this ^^^ is good advice. I have the first ARRL Handbook I bought new in 1975, plus have collected ARRL Manuals from other years from 1941 to 2011. When working with older tube equipment, the older manuals come in handy. One interesting thing reading ARRL radio doctrine over a 70 year period is how some gospel of 1941 is overturned in later years, due to a greater understanding of the technology. On the other side of the coin, it is impressive how correct some of the radio innovators of 100 years ago got the theory that has stood the test of time.

Everyone should own a contemporary ARRL Handbook and a ARRL Antenna Book. Both are worth every penny, but don't ignore other equally valid radio related reference material that may not be ham-centric.

I bought this ARRL Handbook brand new in 1975. There was no Amazon back then. ;)
BTW, The ARRL Antenna Book has also grown considerably in size since my first in 1977.




This "The Amateur's Code" is from the 1941 ARRL Handbook, resting on the 1948 edition. Interesting.






I love this old stuff!
 

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So I put together an antenna with stuff I had in the garage. I used the LDG 4:1 Unun and 123.15 feet of wire. 78.8 on one side and 44.3 on the other. Just to be sure I didn't get too radiating much down the coax (since I don't know which kind of Balun/Unun that is) I put a few magnets and a few coils in the coax 22' down.

I got it out there but didn't have time to get it up on Sat. but laying on top of the 4 ft high wooden fence it measured 1.2 on most of the bands. Awesome.

Today I got it up a little higher, maybe 20'. Not as high as I hope to get it but it got dark on me. Now that it's up a little bit it's more like 2 - 2.5 on the same bands. Not what I was hoping for.

I guess my next step is to get it a little higher to test and order some more parts like that Balun Designs Balun. Still looking at which one. Might go for the Carolina Windom version with the vertical part. Still looking at coax vs. ladder line too. It's a 100' or so to the feed point from my shack.
 
Although it's been done before, you normally don't feed an unbalanced antenna with balanced line. The feedline will radiate all the way back to your shack and negate the benefit of using balanced feedline. If cost is the issue, feed it with the cheapest RG-8, RG-8X or even RG-58 coax you can find.

BTW, as you raise your antenna higher off the ground the feed point impedance increases. Where did you get the starting lengths? You might want to lengthen the wires a bit (twist and solder additional wire), then fold the the wire back on itself at each end and twist to shorten and lengthen to the best match at the desired height. Remember to make changes proportionally, i.e. if 6" on the short end, 12" on the long end.
 
Meaning not normal to feed an OCF with ladder line? Gotcha. I was thinking ladder line would be tempting for a regular dipole. The OCF does fit my yard better so I could pick up rg-58.
The length came from the formula on this website trying to tune for the 75meter end of the band.
http://www.balundesigns.com/content/OCF Antenna.pdf

Twist and solder to lengthen. Got it. But twist the extra at the end back on itself? Its insulated wire so does that shorten the effective length without the bare wire touching?
i couldn't find a good explanation of that. Lots of exact lengths then pictures of a lot of wire taken up attaching to a balun and loops around insulators. Is it end of the loop to end of the loop or total length of wire from metal contact to the end? I'm used to thinking D.C. so this does take some getting used to.
 
An OCF is unbalanced. You feed balanced antennas with ladder line. I've not looked at the other suggested designs on the site. I always use the measurements in the below graphic.

To adjust the length of the antenna, pull or release length on the ends proportionally and wind the excess tightly around the radiator. Doesn't matter if insulated.
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seangt are you using a tuner? The exact length is not as super critical if you are. I used the Balun designs lengths as well and it works good. Mine is low at about 25'.
 
Yep, that's the diagram on the .pdf I was using. Guess I should have left a little more wire and followed the picture instead of trimming for 75. No problem, I know how to solder. I'll try to get it higher and play with the lengths.

I am am using a tuner but I'd like to get it higher and tuned right. Kind of a challenge now.

Thanks for for the help. I'll catch y'all on the air soon.
 
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