I'm mulling the design/homebrewing of a hexagonal 20/17/15/12/10M wire
beam a la the Traffie Hexbeam. The problem with just about all projects
like this is the number of up/down iterations required to tweak the
tuning of the things. Put it up, calculate the required changes in
element lengths, take it down, make the adjustments, put it back up to
check it again, pull it down and go thru the whole cycle ad nauseam.
Pain in the tush.

I've seen suggestions here and there about simply aiming a beam
vertically upward and doing all the tuning at ground level instead.
Which would save an awful lot of time and effort. If it works. Does
anybody around here have any experience with this method and if so how
succesful was it?

Thanks,

Brian w3rv

On 1 Dec 2005 08:23:30 -0800, "Brian Kelly" wrote:

I'm mulling the design/homebrewing of a hexagonal 20/17/15/12/10M wire
beam a la the Traffie Hexbeam. The problem with just about all projects
like this is the number of up/down iterations required to tweak the
tuning of the things. Put it up, calculate the required changes in
element lengths, take it down, make the adjustments, put it back up to
check it again, pull it down and go thru the whole cycle ad nauseam.
Pain in the tush.

I've seen suggestions here and there about simply aiming a beam
vertically upward and doing all the tuning at ground level instead.
Which would save an awful lot of time and effort. If it works. Does
anybody around here have any experience with this method and if so how
succesful was it?

Thanks,

Brian w3rv

It will get you close. However it really depends on the front to
back of the antenna. Dipoles do poorly this way, 2 element beams
slightly better. I've done 3 element 6m beams with the reflector only
4ft off the ground pointing up with excellent success. Seems the
breakpoint is some where around better than 10or 12 DB F/B ratio.

You do need distance from the ground or it acts like a reflector
and messes with your measurments.


Allison

"Brian Kelly" wrote in message
oups.com...
I'm mulling the design/homebrewing of a hexagonal 20/17/15/12/10M wire
beam a la the Traffie Hexbeam. The problem with just about all projects
like this is the number of up/down iterations required to tweak the
tuning of the things. Put it up, calculate the required changes in
element lengths, take it down, make the adjustments, put it back up to
check it again, pull it down and go thru the whole cycle ad nauseam.
Pain in the tush.

I've seen suggestions here and there about simply aiming a beam
vertically upward and doing all the tuning at ground level instead.
Which would save an awful lot of time and effort. If it works. Does
anybody around here have any experience with this method and if so how
succesful was it?

Thanks,

Brian w3rv


Another local Ham and I have built two monoband 20 meter versions of the
HexBeam
utilizing info from W1GQLs hexbeam website (one with PVC spreaders and one
with fiberglass rod spreaders). Neither had to be adjusted at all after the
original wire length was cut. Mine has usable tuning at just above ground
level and it's expected to get only better with height, as the other one
did. Granted, we didn't have the other band elements to fuss with. If you
can get element lengths and vertical separation distances from someone with
a working multibander chances are you won't need to do any adjusting on
those, either. W1GQL has suggested, with the finite lifespan of such
antennas and the current lowpoint of the sunspot cycle, that there is no
overwhelming need for 10, 12, and 15 meter elements for at least the next
couple of years. You might try building your antenna as a monoband 20 meter,
but construct the antenna with sufficient spreader tension and bow depth
that you can later add additional bands. The foregoing advice is free and
not necessarily valuable, but is given with friendly intent.(G) My own
fiberglass HexBeam has a 30" bow depth and I may yet attempt to add a band
or two later. Good luck with yours however you choose to build it.

Harold
KD5SAK

Harold E. Johnson wrote:
I've seen suggestions here and there about simply aiming a beam
vertically upward and doing all the tuning at ground level instead.
Which would save an awful lot of time and effort. If it works. Does
anybody around here have any experience with this method and if so how
succesful was it?

Thanks,

Brian w3rv

Works fine with a yagi, I've always just lashed a 2 x 4 to the tower and
"hung" the antenna off the side of the tower pointed straight up. There's a
null off the bottom of the yagi, and it ignores the tower as well. Not sure
of the topology of your "hexbeam" thingie, but if you can get it to ignore
things around it, the reflector, if it's doing any reflecting at all, will
remove the ground from the tuning process.

The "thingie" is a 'po boy's horizontally collapsed vertically expanded
two element yagi sort of contraption.

http://midcoast.com/~w1gql/hex/hexbeam.htm

Great little rotatable array for those in situations where installation
space is cramped. Which is what I'm stuck with. Just like full-size
yagis they have decent F/B ratios, normally anywhere from 10 to 20dB.
So based on your experience I should be able to use the Sidearm Method
and get the results you've gotten.

Thanks!

W4ZC

Brian w3rv

wrote:
On 1 Dec 2005 08:23:30 -0800, "Brian Kelly" wrote:


.. . . .

I've seen suggestions here and there about simply aiming a beam
vertically upward and doing all the tuning at ground level instead.
Which would save an awful lot of time and effort. If it works. Does
anybody around here have any experience with this method and if so how
succesful was it?

Thanks,

Brian w3rv

It will get you close.

.. . . Good. Beats having to taking the beam down and putting it back up
several times just to get in the ballpark. I expect to have to do a
couple of these final tweaking cycles after rough tuning at ground
level. Would be a *big* help.

However it really depends on the front to
back of the antenna. Dipoles do poorly this way, 2 element beams
slightly better. I've done 3 element 6m beams with the reflector only
4ft off the ground pointing up with excellent success. Seems the
breakpoint is some where around better than 10or 12 DB F/B ratio.

Per my response to W4ZCV hexagonal beams typically have 10-20 dB F/B
ratios so they're in range of your "breakpoint".

You do need distance from the ground or it acts like a reflector
and messes with your measurments.

Understood. Looks like you and W4ZCV are basically in agreement so I'll
follow you two in this direction.

Thanks!

Allison

Brian w3rv

kd5sak wrote:
.. . . .

Another local Ham and I have built two monoband 20 meter versions of the
HexBeam
utilizing info from W1GQLs hexbeam website (one with PVC spreaders and one
with fiberglass rod spreaders). Neither had to be adjusted at all after the
original wire length was cut.

Somebody did something right.

Mine has usable tuning at just above ground
level and it's expected to get only better with height, as the other one
did.

Without any noticeable resonant point or F/B ratio shifts??

Granted, we didn't have the other band elements to fuss with. If you
can get element lengths and vertical separation distances from someone with
a working multibander chances are you won't need to do any adjusting on
those, either.

I'm early into my education on building hexbeams and I've seen a bunch
of this type info published but have not yet dug very far ito it.

W1GQL has suggested, with the finite lifespan of such
antennas and the current lowpoint of the sunspot cycle, that there is no
overwhelming need for 10, 12, and 15 meter elements for at least the next
couple of years.

I don't particularly agree with that. This past weekend hi-band
conditions were below average for the current period but any number of
individual stations operating in the CQ DX CW contest logged hundreds
of 15M contacts each in dozens of countries. Their results on 10M were
dramatically down vs. their results on 15M but their results on 15M
were only down by maybe 20% compared with last year.

I've spent a lot of hours chasing DX on 15M thru a number of sunspot
lows. The biggest problem 15M has is that during the lows the
expectations are that the band is dead like 10M is dead and not worth
bothering with. So they don't. Which is their loss because any number
of times there are great openings on 15M but the few who do tune the
band are all listening instead of transmitting so of course the band
seems "dead". 15M is a gottahave here.

You might try building your antenna as a monoband 20 meter,
but construct the antenna with sufficient spreader tension and bow depth
that you can later add additional bands.

That's reasonable. After thinking about it 12/10M really are coming up
as complete losses so a 20/17/15M version would be a good compromise as
far as the payoffs for the investments in effort go.

The foregoing advice is free and
not necessarily valuable, but is given with friendly intent.(G)

.. . so are my questions (G).

My own
fiberglass HexBeam has a 30" bow depth and I may yet attempt to add a band
or two later. Good luck with yours however you choose to build it.

Thanks. I'll need it.


Harold
KD5SAK

Brian w3rv

On Thu, 01 Dec 2005 17:19:04 GMT, kd5sak wrote:

"Brian Kelly" wrote in message
oups.com...
I'm mulling the design/homebrewing of a hexagonal 20/17/15/12/10M wire
beam a la the Traffie Hexbeam. The problem with just about all projects
like this is the number of up/down iterations required to tweak the
tuning of the things. Put it up, calculate the required changes in
element lengths, take it down, make the adjustments, put it back up to
check it again, pull it down and go thru the whole cycle ad nauseam.
Pain in the tush.

I've seen suggestions here and there about simply aiming a beam
vertically upward and doing all the tuning at ground level instead.
Which would save an awful lot of time and effort. If it works. Does
anybody around here have any experience with this method and if so how
succesful was it?

Thanks,

Brian w3rv


Another local Ham and I have built two monoband 20 meter versions of the
HexBeam
utilizing info from W1GQLs hexbeam website (one with PVC spreaders and one
with fiberglass rod spreaders). Neither had to be adjusted at all after the
original wire length was cut. Mine has usable tuning at just above ground
level and it's expected to get only better with height, as the other one
did. Granted, we didn't have the other band elements to fuss with. If you
can get element lengths and vertical separation distances from someone with
a working multibander chances are you won't need to do any adjusting on
those, either. W1GQL has suggested, with the finite lifespan of such
antennas and the current lowpoint of the sunspot cycle, that there is no
overwhelming need for 10, 12, and 15 meter elements for at least the next
couple of years. You might try building your antenna as a monoband 20 meter,
but construct the antenna with sufficient spreader tension and bow depth
that you can later add additional bands. The foregoing advice is free and
not necessarily valuable, but is given with friendly intent.(G) My own
fiberglass HexBeam has a 30" bow depth and I may yet attempt to add a band
or two later. Good luck with yours however you choose to build it.

Harold
KD5SAK

You could also join the Yahoo newsgroup that is devoted to the Hexbeam.
There is an awfull lot of info in the archives there including photos.
Eskay.

On 1 Dec 2005 23:38:42 -0800, "Brian Kelly" wrote:


wrote:
On 1 Dec 2005 08:23:30 -0800, "Brian Kelly" wrote:


. . . .

I've seen suggestions here and there about simply aiming a beam
vertically upward and doing all the tuning at ground level instead.
Which would save an awful lot of time and effort. If it works. Does
anybody around here have any experience with this method and if so how
succesful was it?

Thanks,

Brian w3rv

It will get you close.

. . . Good. Beats having to taking the beam down and putting it back up
several times just to get in the ballpark. I expect to have to do a
couple of these final tweaking cycles after rough tuning at ground
level. Would be a *big* help.

However it really depends on the front to
back of the antenna. Dipoles do poorly this way, 2 element beams
slightly better. I've done 3 element 6m beams with the reflector only
4ft off the ground pointing up with excellent success. Seems the
breakpoint is some where around better than 10or 12 DB F/B ratio.

Per my response to W4ZCV hexagonal beams typically have 10-20 dB F/B
ratios so they're in range of your "breakpoint".

You do need distance from the ground or it acts like a reflector
and messes with your measurments.

Understood. Looks like you and W4ZCV are basically in agreement so I'll
follow you two in this direction.

Thanks!

The yabut/gotcha is until the beam is acting like one you don't have
the F/B ratio to rely on so it may take an iteration or two before you
converge. Once you are in the fine tuning range it should work
well pointing it up. This is a problem that most Yagis don't have
as tuning is limited to tweeking the match for the driver and maybe
the driven element length to make the match work right. So what
regular yagis are tuned up pointing up they are really just having the
match set up correctly(usually).

Allison