[Top] [All Lists]

[TowerTalk] homebrewing short yagis

To: <>
Subject: [TowerTalk] homebrewing short yagis
From: (
Date: Mon, 1 Oct 2001 17:05:56 EDT

 << In a message dated 9/30/01 11:28:01 AM Pacific Daylight Time, writes:  << 
    Hello All,
     I have an unusual antenna project in mind and could use some direction.
    I'm planning to build a "short yagi" for 6 meters.  I've gone through my
    limited collection of reference books, and haven't found much help.  I 
    several editions of the Handbook, a fairly extensive QST collection, and a
    94 edition of the ARRL Antenna Book.  I've been considering some of the
    Antenna compendium series, is there a particular issue that discusses 
    yagis?  I'm sure they are all great, but can't afford to buy the whole
    What I have in mind is a two or three element 6 meter yagi on a 6' boom.  
    want to keep the element lengths less than 6' overall.  At  6 meters, I
    think this should still produce a reasonably efficient antenna.  I realize
    that most people don't need to reduce the size of a 6 meter yagi, so I 
    expect to find "cook book" directions.
    And while I'm at it, what do you guys think about loading methods?  Anyone
    care to comment on loading coils versus linear loading?
    Thanks,  Dan
    Dan Evans N9RLA
    Scottsburg, IN 47170
    IN-Ham list administrator
    QRP-l #1269
    1/2 of the N9RLA /R no budget Rover Team
    Check out the Rover Resource Page at:
   Any project has some merrit.  I honestly can't find any here loading 6M 
elements based on building beams for a long time as has Jiri OK1RI doubting 
the increased trouble and less performance.  I'd forget the loading as you 
will need a fair test set up to tune the loading elements for pattern and it 
will end up taking many hours unless you really know what you are doing.  A 
6M beam is already small so why waste the effort and complicate the design?  
Unless you find an artcile with specific data on such beam you have a 
problem.  See Communications Quarterally Winter/98 by W1JR who had very good 
results with his version.  
AntenneX has a great 3 element quad (no loading coils) in their Qct issue 
with great pictures.  Give that a try also.  They used a lathe to make parts 
but you can duplicate it with a wood drill and wooden or fiberglass 3/8" 
dowels and a 2x2" wooden boom for the economy model.

In your version you would need special insulators to hold the loading 
whatever it is as well as the elements.  Very few have any of this hardware.  
You will have an increased number of joints/element.  You need to be intimate 
on feed systems and their adjustments and the main goal should be there isn't 
any RF spill over down the coax shield.
I built a couple of 6M full size 5 element beams on a 16' boom based on a 
proven design of 10.5 dBI & 25 dB F/B and used a special feed system.  I had 
all the hardware from many other projects and tubing from Boeing Surplus.  I 
used a continious diameter 5/8"X.028" tubing progressively beefed up in the 
center--inside.  There were NO ELEMENT JOINTS.  It hasn't required any 
electrical or mechanical maintenance in 9 years.  I clean the feedpoint 
connections once in awhile.  Since I used different tubing than the original 
W8CC model, I had to use Eznec to finalize the lengths back when computers 
weren't so fast--many hours and hours.  It also has a very interesting 
"double dip SWR curve" which I've observed only on this yagi.  This has great 
possibilities--stay tuned.  Both beams still work great but it took a 
lifetime of experience to do it better than I could buy.  The aluminum cost 
in this case was a few bucks but the Computer, Mill, Lathe time and 
Satisfaction of building it and using it was very very high.  
Back in 1947 I had ideas of making a 10M wire beam somehow using bamboo or 
something to hold the wire.  Fortunately an Elmer friend straightened me out 
and told me to forget this total nonsense and buy the Hy-Lite 3 element 10M 
beam advertised for $19.95.  It used stand off insulators to hold the 
elements on the twin boom.  It took about 15 minutes to assemble and about 5 
minutes to install on a 10'  tower (with PP motor) on the roof.  This is 
somewhat of an assembly and installation record.  That later was changed to a 
single boom "Plumbers Delight" construction.  
Now after spending "Many Big Bucks" collecting aluminum tubing over the years 
so I could save all kinds of  $$$ building my own, I'm here to tell you 
that's a "Total Myth.  I had to build special racks to hold it also.  I'd be 
very happy if I could sell my stock pile of aluminum as it's the most 
expensive mistake one can make if you think you are going to save money.  
Even with all this tubing there will be a size, length and quantity you just 
don't have at times.  Quads use fiberglass rods that only have to be strong 
enough and only the copper wire size is critical for size and is available in 
small steps at a low cost--in particular for scaling.  Forget trying to scale 
tubing for test models.
I've tried just about every beam configurations there is which all this 
available tubing and hardware I've made permitted me to do.  Big Deal!  I 
purchased a Big Lathe and Mill to assist and it saved a lot of time.  At one 
time it was perhaps justified for the serious antenna man.  Forget about it 
now.  I've uncovered some very effective concepts I use some would like to 
know about real bad.  They can't afford them! 
The cost of aluminum is so high now for small purchases you can't afford to 
build a beam and the technical concepts for the average Appliance Operator 
are beyond his reach.  There is a simple solution:
There are Antenna Manufacturers out there like M2, Antenna Mart & Raibeam 
that have can provide you a well made beam of Hi-Tech Mechanical and 
Electrical Design you can't duplicate for "love nor money."   M2's beams 
designs are so good even I copied them.  Of course it ended up costing me 
many many times more.  I only had the advantage of being able to add what I 
thought I couldn't live without for whatever it was worth.  One DE was a FD 
set for 100 ohms that was fed with balanced 100 ohm coax into a Johnson Match 
Box Tuner.  It works great on any beam.
I've operated 2 years of the last 5 on 6M running 100W in SD using a 2 
element quad I made in an hour.  It's 25' high fed with 100 ohm balanced coax 
into a 6M version of the Match Box.  It worked great but then like the old 
days I ran the coax directly into the balanced link and series Xc of a HA6 
Transverter-modified.  I made hundreds of contacts even holding a frequency 
for as along as 3-4 hours of one contact after another from one coast to the 
other time after time.  It was like being on a DX Pedition in a reasonably 
rare grid square.  With great audio they got the call correct each time when 
I stated it "just once per QSO."  2 element beams work great at 25' on 6M and 
should be a standard antenna for 6M.  I suggest 3, 5 and more elements 
starting at 50-100'.
Here is what I would suggest for today that will save you a fortune in money 
and time.  I even follow my own advice.  I wanted to try the Raibeam 6M 2 
element on a 2' boom weighing about 3 lbs for the 25' antenna and the Raibeam 
Butt Kicker 5 Element Beam on a 23.5' boom I've repeatedly heard others using 
on 6M.  They stood out on 6M repeatedly and I had to find out for myself even 
thought I knew all the technical details having discussed them with Chuck 
Smith of Raibeam over the last 5 or so years.  
So I spend the money for 2 of the 2 elements and the 5 element on  a 23' boom 
(first time for a yagi since 1947).  It was one of the best investments I 
ever made even though I could have perhaps duplicated it with a lot of time.  
>From box to installed on the tower for all 3 beams took a couple of hours all 
alone.  It dominated 6M with 100W like I have never before even with the W8CC 
5 element beam.  The details will be in 73 Mag along with a Front Cover 
Picture showing the 5 element along with 2-2 element beams vertically 
polarized about 8' apart and 10' below.  I ran polarization shift tests and 
gained the advantage of reduced QSB on 6M that can be very active at times 
and on other bands.
The 2 element Raibeam will do about what the 2 element quad will do at 25'.  
I'd give it or a 2 element quad a try but you will really need a 100 ohm 
balanced feedline for a quad and connected to a Match Box in the shack for 
the best results.  For 2 element the Z is around 70-100 ohms depending how it 
is tuned.  From box to tower shouldn't take over an hour and you are in for 
"Immediate Success" on the air.  No time design delays.
I just saved you a big chuck of money and time.  I will humbly accept all 
forms of money, stocks and bonds for your appreciation hi.  k7gco

List Sponsored by AN Wireless:  AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 100 feet for under $1500!!

FAQ on WWW:     
Administrative requests:

<Prev in Thread] Current Thread [Next in Thread>