[TowerTalk] Cut off extra 7 ft of mast or leave it?

[Richard Zalewski]

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 at 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 at telus.net> wrote:
> >
> > Date: Sun, 22 Nov 2020 18:39:24 -0800
> > From: David Winarsky <david at winarsky.com>
> > To: TowerTalk at 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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