HF Baluns - How to pick the right one for the job

[rfoverlord]

:drool: mole,
now that you have led the sheepeople to water, do you think they will drink?

 

[Dealer]

:drool: mole,
now that you have led the sheepeople to water, do you think they will drink?

____________________________________________________________________________

We came to the water hole, Yet we do not drink of this tainted water..

Make no mistake, DX Engineering is a well respected company however
sometimes in the advertising dept. the hype will lure the sheep to drink
tainted water.

This thing regarding voltage baluns verses current baluns is misleading
at the very best !
Voltage baluns are almost non existent except for maybe in trans-matches
aka.Tuners.

Array Solutions, Balun Designs, rate right up there with DX and on close reading
you will find that the market is better served by the two afore mentioned when
dealing with wire antennas.

To get a voltage balun you would almost have to special order it and in most cases
the builder would in fact try and talk you out of it.
Some cases may require one, however cant think of any at the moment.

What has prompted this reply is their ads regarding a True Windom and a OCF Dipole antenna
which BTW is two completely different animals.

No one in their right mind would feed a Windom with a single wire ( A true Windom )
this day and time.

They in fact stated that these antennas if feed correctly are resonate on even
harmonic frequencies and the desireable feature about them they can be operated
without the use of a tuner.

They correctly gave feed point between 400 @ 600 ohm for this Unbalanced
antenna. So why not use a 1 to 1 balun and 450 ohm ladder line ?

The answer is simple you would be feeding a Unbalanced antenna with a balanced line
so then a tuner becomes necessary so as to use the internal balun for the twinlead
connection point.

The transmitter wants to see a 50 ohm load and loss will be much less through a balun
installed at the antenna feedpoint, and while twin lead offers lower loss than coax it is rare
to be able to install it without problems inherent to twin lead or ladder line.

The purpose of the OCF is to have a antenna that Does Not require the use of a tuner on
80 thru 6 meters except for the odd multiples i.e 30,15,ect..

A 4 to 1 or 6 to 1 or even 5 to 1 to optimize based on height of wire up to a height
that is to be considered reasonable.

A 9: to 1 is a total unreasonable balun to use on a flat top or inverted V Dipole
antenna.

Closer reading shows the primary use of these baluns are for Vertical Wire antennas

You will not find that recommended any where else that I know, YET I can see
where that may be usable at 100ft in the Air Flat Top.

How many people do you know Can or Would install a 80 meter wire at that height

No mention at all of a coaxial feed of 50 ohms, I would venture to say based
on the hundreds of reviews I have read, that they are In Fact using coax as I am
and very happy with the antenna.

I do have a issue to deal with but of no fault with the antenna.

Now If someone would like to send me one to try! a 9 to 1 current balun and include
a good read on why I should be doing this, then I may drink of the water.

I have been wrong before, Infact almost every day ! That at least shows that I
am doing something. Even if its wrong.
____________________________________________________________________________________

After futher research, I find the correct usage for a 9 to 1 balun is to connect a 50 to 450 ohm
feed line !! Asymmetrical to Symmetrical in the feed line.

A case in point when using 450 ohm twinlead and 50 ohm coax to enter the shack,the balun
inserted at that point.


Regards,
John--- KD5WJY

 

[hookedon6]

Jay good point..... I am seeing the same thing right now with my Signal Engineering Lightning 4+ Quad Beam. If I change the coax length in the Shack it will change my SWR. Indicating that my coax is part of the antenna system and radiating..... A bad thing:thumbdown: My question is how do I fix this? what is the correct way to tune this beam so the coax will not becoming part of the antenna and radiate
Will tuning the antenna with a 3' or 6' foot jumper connected to my antenna analyzer fix this? When the beam was originally tuned it was tune with the analyzer connected to the end of the feed line inside my shack 118' away. That might be my problem. I have 2....... 1:1 balun kits from Palomar Engineering that I am going to attach at the feed point to help stop RF from flowing back down the feed line But I want to tune this beam correctly so all the RF radiates out of the antenna not the feed line.

Help

VSWR of 1:1 and a resonant antenna are really two different things.

your VSWR meter is in the wrong place. it needs to be installed at the FEEDPOINT of the antenna. so it reads the antenna ONLY and not the coax and the antenna combined.
tune the ANTENNA at the feedpoint and just run the coax to it.
yeah,... i know the next reply: "but my VSWR shows (insert number here) when i do that"..... well,the meter is "lying" to you.

if you are REALLY worried about it and are using a monoband antenna, you can fool your meter into "thinking" that it is at the antenna feedpoint instead of at the radio output by running a TUNED feedline in multiples of 1/2 wave lengths from the rig/meter to the antenna (compute the length of tuned feedline using the velocity factor of the coax and frequency) and then tune the antenna to 50 ohm's.

 

[rfoverlord]

A little more for curious minds, HF verticals,and baluns
http://www.eham.net/forums/Elmers/202315?page=1

 

[W5LZ]

The basic idea is to 'cure' a problem where that problem exists, not somewhere else. If using a balun/unun can do that, then DO that. If it can't then don't waste your time. the most 'bestest' thingy is to have an antenna that's input matches the feed line's, which in turn matches the transmitter's output impedance. There are several ways of going about that, pick the one best suited to you and your situation. That's typically good for one 'spot' on a band, and things start deteriorating the further you move from that 'spot'. If that deterioration in performance is 'acceptable', then who cares. If it isn't, then you have to be able to change things back to 'good' again. That 'change things' can get unpractical fairly quickly. But, that practical/unpractical thingy just depends on what's 'acceptable' to you (or your radio?). A little bit of inefficiency is absolutely normal, not a biggy at all. A lot of inefficiency is the pits.
Microsoft found out that a universal "plug-n-play" is more a "plug-n-pray" thingy than fact. The same goes for antennas... have fun.
- 'Doc