[TowerTalk] Lowering mast on fixed tower

[Jim White, K4OJ]

Hi Bob...

Dear Santa - All I want for Christmas is servicing of my HF Christmas Tree!

Stacked yagis are rough...

Unless you have a very very heavy duty mast with multiple thrust 
bearings, etc. climbing of the mast with ladder steps is not an option 
so, you have to lower it into the tower...

The lower antennas have to either be slid up or removed to get at the 
top one... yes, it is a lot of work...

The biggest bummer of this type of installation usually is that the tape 
that holds the top feedline to the boom and the mast that will fail over 
time and suddenly you have a dangling mess which is, of course, out of 
reach...

There was a great article in NCJ an issue or two ago by Robin Midgett 
KB4?... he developed a cable and pulley system that allows the  mast to 
be lowered and re-raised very smoothly - it is a massive system but 
suspect that it is one of those things that you are really glad you have 
if you need to use it!

A come along is the usual method of raising and lowering of the mast - a 
secure attachment to the mast for a grab point is mandatory - typically 
pieces of lumber or angle will be placed across horizontal rungs to 
support the weight of the mast and antennas when the mast passes below 
the rotor plate...

NOTE: The usual rotor plate does not have a magical 2+ inch hole where 
you want it so the mast can easily pass through it during antenna 
servicing... of course...

GL

Jim, K4OJ




Bob Gates wrote:
> Please excuse what, for most, is probably an elementary question.  But I feel
> like Rip van Winkle, coming back into the hobby at such a late date.  I have a
> question that I cannot figure out the solution to in my mind.  Assume a fixed
> height tower, say Rohn 45G.  Assume a rotor mounted to an accessory plate 5'
> below the top, with a 20' heavy duty mast extending up through the tower, Then
> assume a yagi installed 10'-12' above the top of the tower.  How does one
> perform maintenance on this antenna?  I assume you would need some means to
> remove the rotor and lower the mast down through the tower.  After work is
> completed, you would then need to raise the mast back up to the desired height
> and reinstall the rotor.  The problem is increased if there is another antenna
> installed on the mast, say 1' above the top of the tower.  Obviously you could
> hire a crane at a gazillion dollars per hour to pick up the assembly and set it
> on the ground.  But how would you do it without one?  Realistically, can you
> climb up the mast to work on the top antenna?
> Thanks in advance,
> 
> Bob  KG7KW
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