[TowerTalk] 5 Band Yagi with more than 2 elements per band

[Grant Saviers]

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 at 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 at contesting.com> On Behalf Of Jeff Blaine
> Sent: Wednesday, July 25, 2018 2:18 PM
> To: towertalk at 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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