Going to agree with Jim. NEVER cut off a perfectly good mast. You never
know when your configuration might change.
Richard
*W7ZR* ex:5C5Z, CN2ZR, K2JSP, W6SBZ, W7KXR, K9ZIJ, W9KNF, W0KDF, W0MQU,
J68ZR, KC6ZR, PJ4/W7ZR, KH2,W7ZR, KH6/W7ZR, V31ZR, VK4AAZ, XE2DV
*Be joyful in hope, patient in affliction, faithful in prayer*
On Wed, Nov 25, 2020 at 4:18 PM David Winarsky <david@winarsky.com> wrote:
> Hi Jim and others,
>
> Thanks again for the input. The tower is a Tashjian LM-354HD and the mast
> is a Tashjian AD-200EH. The mast is 2” OD by .25” wall. It looks like it is
> galvanized steel.
>
> I’m going to go with the below setup. I’ll send pics when it’s up! I got
> the Steppir assembled yesterday, so next step with be putting the Jk401
> together and the assembling all on the tower.
>
> David K6ZD
>
>
> > On Nov 24, 2020, at 09:41, Jim Thomson <jim.thom@telus.net> wrote:
> >
> > Date: Sun, 22 Nov 2020 18:39:24 -0800
> > From: David Winarsky <david@winarsky.com>
> > To: TowerTalk@contesting.com
> > Subject: [TowerTalk] Cut off extra 7 ft of mast or leave it?
> >
> > <Im putting up my first tower, a LM-354HDSP with a Steppir DB11 and a JK
> 40 meter horizontal dipole, both in the same mast. I have a 20 ft 2 in OD
> mast from Tashjian and am wondering whether I should cut off the unused
> length or leave it?
> >
> > <Karl at Tashjian suggested I install the rotator plate 3 ft below the
> top of the tower and the DB11 2 ft above the top, with the JK40 8 ft above
> that (10 ft from the top of the tower). That will leave 7 ft of the mast
> unused.
> >
> > <Do you folks recommend I leave the extra 7ft of the mast in place or
> cut it off?
> >
> > <Appreciate the input and any other comments or suggestions on my plan.
> >
> > <73,
> > <David K6ZD
> >
> > ## what kind of mast ? what is the OD ? wall thickness ? KSI
> strength of mast. aluminum or steel. is it chromolly or dom, or plane
> jane 35 ksi ?
> > Knowing that, simple software calcs to provide bending moment where
> mast enters the tower.
> > I would put the rotor plate down six to eight feet. That reduces the
> stress on the top of the tower... by a bunch. Leaving 14 foot above the
> top of the tower. Ok, then put the 40m rotary dipole at the top, or close
> to the top.
> > Align the 40m rotary dipole so its inline with the steppir boom.
> Then just do mental math..and either add or subtract 90 degs from your
> rotor indicator dial.
> > Depending on snow and ice, and length of the 40m rotary dipole, you
> might require a non conductive overhead truss line on the 40m dipole,
> hence mounting the
> > 40m dipole 3-4 feet below top of mast. Remember to cap off the top of
> the mast. DXE sells caps. Then no water running down the inside of the
> mast.
> >
> > Jim VE7RF
> >
> > _______________________________________________
> >
> >
> >
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>
>
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