[TowerTalk] Re Plumbing a Tower

[Roger (K8RI)]

On 7/29/2010 1:11 PM, jimlux wrote:
> Robrk wrote:
>    
>> How about one of the laser level light beam things? I have the cheap, $39, Craftsman, that shoots a red line, vertical or horizontal with bubbles. It has a camera tripod hole in the bottom.
>> More dollars gets auto leveling, digital readout and a mount for the owl.
>>      
I have a couple that are no where near that bad. The spot at a 100 yards 
isn't much over an inch.
>> Sent from my iPad
>>
>>      
> The challenge is the beam divergence on these inexpensive levels.  If
> it's basically a laser pointer in a housing, then a divergence of a few
> milliradians is typical.  That means the beam spreads about 0.5%.. at
> the top of a 100 ft tower, the spot is 6" in diameter.  (and it's hard
> to see in the daytime).
>
> They work great indoors across a room at 15 feet (the spot is still nice
> and small).
>    
I still find the accuracy pretty dismal. Good enough, but for the 
price...pretty dismal.

73

Roger (K8RI)


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