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

On Wed, 16 Jun 2010 10:24:26 -0700 (PDT), "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

I have an old Radio Shack 11 meter 3 element beam that I plan to put
on 6 meters. I once did the EZNEC modeling with the boom length being
the only constraint. It was possible to come up with a model that
would work with a direct match for 50 ohms to the driven element. I
hope to try to construct it soon.

The problem with holding a few parameters constant is that you have to
accept whatever gain, patterns and such that come with the deal.

I also have a very old Mosley 15 meter 3 element beam that I want to
modify to 17 meters. I am having a lot of fun with PSK31 there with
poor antenna setup now.

Tower space is a limiting factor in my case and I am not interested in
anything that compromises my A3S!

I wish you were close to me rather than 2306.9 miles, I am looking for
an old bargain tri band to tinker with. There is a lot there I don't
understand!


John Ferrell W8CCW

The problem with holding a few parameters constant is that you have to
accept whatever gain, patterns and such that come with the deal.

Well I did find plans for a 6 elem on a 17.5ft boom. The boom on the
old A4S is 18Ft. If I use the parts off my old A3
and my A4 I should be able to come up with all the parts for the 6
element. And its direct connect.


I wonder how far above the A4 the 6 meter needs to be. I only have a
5ft mast.

my DX800 rotor should handle it.

Since no one stepped up who has the experience and knowledge, I will
offer an opinion:

Further would be better but the more practical decision will be based
on what is reasonable and maintainable.

Everything is a compromise!

On Thu, 17 Jun 2010 09:05:11 -0700 (PDT), "R.Scott"
wrote:

The problem with holding a few parameters constant is that you have to
accept whatever gain, patterns and such that come with the deal.

Well I did find plans for a 6 elem on a 17.5ft boom. The boom on the
old A4S is 18Ft. If I use the parts off my old A3
and my A4 I should be able to come up with all the parts for the 6
element. And its direct connect.


I wonder how far above the A4 the 6 meter needs to be. I only have a
5ft mast.

my DX800 rotor should handle it.

John Ferrell W8CCW

On 6/17/2010 11:05 AM, R.Scott wrote:
The problem with holding a few parameters constant is that you have to
accept whatever gain, patterns and such that come with the deal.

Well I did find plans for a 6 elem on a 17.5ft boom. The boom on the
old A4S is 18Ft. If I use the parts off my old A3
and my A4 I should be able to come up with all the parts for the 6
element. And its direct connect.


I wonder how far above the A4 the 6 meter needs to be. I only have a
5ft mast.

my DX800 rotor should handle it.



I have plans for a very good 6 element beam which is 15.53 feet from
reflector to D4. I could scale it to the element taper you have if needed.

It will not be a direct connect however, as those are almost never
optimal designs for gain, F/B or pattern. They are optimized to be 50
ohms with the rest subservient to that. Most of the designs I have
would be around 22 ohms so this one is probably in that area. A gamma
match is easy to make.

tom
K0TAR

On 6/19/2010 8:33 PM, tom wrote:

I have plans for a very good 6 element beam which is 15.53 feet from
reflector to D4. I could scale it to the element taper you have if needed.

It will not be a direct connect however, as those are almost never
optimal designs for gain, F/B or pattern. They are optimized to be 50
ohms with the rest subservient to that. Most of the designs I have would
be around 22 ohms so this one is probably in that area. A gamma match is
easy to make.

tom
K0TAR

Sorry, I should have looked before leaping, it's 5 elements on 15.5 feet.

tom
K0TAR

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.

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

On Jun 20, 5:27*am, K1TTT wrote:
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.

Or a folded dipole driven element.
--
73, Cecil, w5dxp.com

John Ferrell wrote:
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.

Cushcraft prided themselves on building antennas with a DC resistance of
0 ohms.

In plain English they were static disipators. At their design frequency
they had an impedance of 50 ohms.

When I lived in Philly, we had a sever lightening problem. Whenever there
were lightening storms there were nearby strikes with all sorts of expensive
EMP problems.

When I put up a cushcraft 2m beam (the 11 element vertical polarization on
the same beam as an 11 element horizontal one) with proper gounding they
all "went away". I wonder if our neighbors suddenly noticed next spring that
the lightening had come back :-)

Geoff.

--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
I do multitasking. If that bothers you, file a complaint and I will start
ignoring it immediately.