Mark,
I modified a 6 element beam to break down in a few minutes and go back together
accurately and almost as fast with no tools required. Some of what I did might
be useful to you.
I now wish I had pics on the qrz page of this. I can take and send pics later
if desired.
The elements are each 3 piece with the outers slipping inside the center. With
the beam assembled and tuned with a spectrum analyzer I wrapped electricl tape
on the outer elements so one edge of the tape is against the inner element.
This controls the depth and avoids measuring on reassembly.
Next I slit the ends of the larger inner elements so there were 4 slits about
an inch long in each end. At the auto parts store I picked up hose clamps with
large plastic wing nuts. I use these to clamp down on the inner element ends
and secure the outers. It wont work with just two slits, you need 4 or the
force required will snap the plastic wings off.
Next I punched small holes in the plastic end caps. Using a 12 foot leader of
mechanics wire I threaded an elastic chord through the full length of the
element. Tie the ends off around a short length if black plastic zip tie.
Make sure the elastic is under tension when the element is assembled. Make
sure there is enough stretch so you can pull the elements out. Snug down the
claps after pulling out the outer elements so you dont loose the clamps.
With the elements out lay them over the top of the inner element. Secure the
outers to the inner with a wrap of double sided velcro on either side of the
boom.
If your boom uses saddles and through bolts to secure the inner element to the
boom your in luck. Loosen the center bolts in all inner elements. Rotate ALL
of them until they lay as parralel to the boom as possible. Mark the saddles
either side of the center element one one saddle. Remove the saddle and put a
shallow notch in it so the inner element has a shallow detent to rest in.
Reassemble, then Mark and notch the next saddle. Reassemble and continue until
they are all notched. When you are done the package should a foot or two wide
and anout 3 feet longer than the boom. Secure the packaged elements with a
couple more strips of double sided velcro.
The feed will take some thought. I flipped mine (gamma match) and made new
brackets so it sat above the driven element which is above the boom and sat
above the driven element the same distance as it sat below it when under the
boom.
When your all done set it up and retune it with an analyzer. There will be
small changes due to the clamps and feed changes.
Another thing I did to save weight, important since your packing it in, was to
use much smaller boom tubing. I run 550 chord from one end up to a stand off
for h pol or to the center element for vpol. This adds a huge amount of
strength, more than what you loose if you do it right.
Gotta go. Dinner out tonight.
73
John
KM4KMU
Sent from AOL Mobile Mail
On Wednesday, February 14, 2018 Mark Spencer <mark@alignedsolutions.com> wrote:
Hi:
I finally took delivery of a suitable LiPo battery to facilitate "back pack
portable" operation at the 50 to 100 watt level. If any of my Canadian
colleagues are interested I can provide the contact details for a Canadian
distributor.
At this point I'm planning on simply taking my 50 MHz three element beam apart
and re assembling it on site. In my view the beam I have isn't really intended
for that type of use and I'm curious if anyone knows of any suppliers for small
50 MHz beams that break down and re assemble quickly and easily. Google
searching on my part didn't turn up anything that is currently in production.
I'm hoping to shift my focus a bit this year and actually reach the true summit
of at least one local mountain (vs simply driving most of the way up via
logging roads.) Having this ability would also have been useful earlier this
year when I had to abort my CO81 visit during the sept contest. In hindsight I
suspect I could have activated the grid for a few hours on foot.
73
Mark S
Aligned Solutions Co.
mark@alignedsolutions.com
604 762 4099
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