Re JK Antennas element clamps:
https://drive.google.com/drive/folders/13AvoiLPBE3I7BUZrMEHn4agqmHV_R8Yt?usp=sharing
Follow link to see clamps for boom to mast and driven element to boom
for my 2L 80m beam from JK.
The mast in the boom to mast jpg is for the boom truss, not the mast.
My mast is 3" alloy and 5 more clamps like the boom clamps hold the
plate to it.
The driven element clamps are eight Stauff clamps under the heavy web
thickness channel Four channel to boom clamps.
All clamps custom CNC milled in 6061-T651 with SS thru bolts.
Up 152' about 3 years and all is perfectly straight. The elements are
not trussed at 100' long.
Grant KZ1W
On 7/29/2018 9:49 AM, kstover@ac0h.net wrote:
Exactly.
Milled aluminum that are bolted to the element plates. The elements are
installed using polyamide clamps on the bottom of the element plates. Look up
polyamide. Kevlar is a polyamide.
The boom to mast plates use specialized stainless steel clamps that have a
flattened section which increase surface area contact between the clamps and
the mast. I can't imagine a JK beam spinning on the mast.
If JK are building the 5BA (updated) again they need to get it up on the
website. It'll sell like hotcakes.
R. Kevin Stover AC0H
ARRL, FISTS, SKCC, NAQCC.
“If it doesn’t work the first time you push the button it won’t work the 20th…Just
stop.”
-----Original Message-----
From: TowerTalk <towertalk-bounces@contesting.com> On Behalf Of Jeff Blaine
Sent: Wednesday, July 25, 2018 2:18 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] 5 Band Yagi with more than 2 elements per band
My experience with quite a number of the JKs is that they use machined aluminum
clamp sets for the boom. I personally don't like working with antennas on the
ground so I build them on a trio of saw horses. The element sag is less than
the saw horse height on all my JKs so that allows me to do the alignment very
easily.
The only muffler clamps I've seen on the JK are for the boom to mast on smaller antennas (15
& 10) - there he has 4x of the clamps and the clamps have a flattened and knurled surface
which bites into the mast. The "problem" with these clamps is when you are setting
the beam direction once it's mounted on the mast. They will absolutely not slip at all so you
have to really loosen them up to get the beam to turn by hand. Of course that is what you
want after you do get the beam direction set.
73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com
On 25-Jul-18 1:59 PM, rlvz--- via TowerTalk wrote:
But don't the JK antennas use muffler type clamps for attaching the elements to
the boom where the elements must be lined up by sight? I hate fooling around
aligning elements by sight only to have them change when you tighten the clamp.
Pre-drilled element brackets are much nicer and my idea of a well designed
antenna.
73,
Dick- K9OM
## I spoke with Ken, W3JK a while back on the telephone, and yes,
indeed, he does make a new and improved version of the oem F12 5BA. It
has more gain, better FB, better FR, better swr than the oem F12 5BA,
and is stronger built....and uses TWO LESS eles than the oem 5BA. The JK
improved version is well though out.
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