On Jun 20, 10:03*am, John Ferrell wrote:
On Sun, 20 Jun 2010 03:27:52 -0700 (PDT), K1TTT
wrote:





On Jun 16, 5:24 pm, "R.Scott" wrote:
I see all kinds of crazy matching sections in posts about 6 meter
beams. How about direct connect. I have an A4S that has major issues
in the traps and I cant find the problem (IE I opened them and cant
find anything) SOOO I have a new A4S coming.

Has anyone taken an old 3 elem tribander and converted it to 6 meter
monobander using the direct connect.

Any Issues.

Would a 4 elem be better since its a long boom ?

I'm pretty sure I know the answers. Just want to confirm and see if
there is any reason not to direct connect rather than through a
hairpin or a gamma match.

Scotty W7PSK

There are at least 3 reasons to use some kind of a matching network.
1. impedance transformation - usually the feedpoint impedance of a
simple dipole in a yagi is not near 50 ohms so the matching system
gives you an easy way to adjust that.
2. it is often easier to build an aluminum element without a center
insulator and feed it with something like a gamma or T match.
3. to keep current off the feedline shield you need to go from the
unbalanced coax to a balanced dipole feedpoint. *gamma matches and
others do that transformation for you.

I am in agreement with all your points. [Not that I am any kind of
authority!]

Many years back I purchased and installed a Cushcraft A3S tri band
beam with the 40 Meter option. The decision was based on past
experience with Cushcraft products.

When I assembled it I was disappointed to find it did not have a gamma
match! Instead it got by with a direct connection to the driven
element with the 50 ohm line. Then it used a jury rig device called a
"choke balun" to keep the RF where it ought to be... It reminded me of
the Gotham Vertical (Google it!) that so many of us fell for way back
when. I assembled and installed it according to the instructions any
way. Much to my surprise, it worked great! I have been very happy with
it.

That led to my taking the ARRL Antenna course and buying the EZNEC
program. *

Some things I model I can make work and some I cannot.
Some things work I cannot model.
I have concluded that direct connection and gamma matches both work
well.

My cumulative experience is that it is difficult to beat the
commercial products at their game.

OTH, the study and construction of antennas has become one of my
favorite recreational pastimes!

John Ferrell W8CCW- Hide quoted text -

- Show quoted text -

A gamma rod is the easiest thing in the world to build...people who
are scared of 'em just don't understand 'em.