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An idea for a simple AZ/EL indicator...



Hi all	, 

I will explain here a solutions for a "precision"
cheap azimuth/elevation indicator.The system shows
the azimut or elevation on a LCD display with
increments of 1 (or less if you want).
It is not perfect, but can help finding the right 
option...


You need two digital counters with + and - inputs.
I have bought them in France ,they cost about 12USD, 
this is the only expense i have done.
For the azimuth indicator ,you need to cut a circle
of plexiglass or equivalent,mine is about  30cm diam.
on the edge of the cicle , drill 360 holes of about 2mm
diam, 2mm deep (this is not so much work as it seems!!).
Or better,You could also make saw cuts the same way, for
example using two blades in parallel.A hot iron will 
probably do it too.Anyway ,i used the drill...
Then i removed microswitches from a computer mouse,
fixed the circle on the antenna  (rotating part ) and
the microswitch on the tower, so when the antenna rotates,
the microswitch opens and closes as it "falls" in the 2mm 
holes.

The same thing for elevation , exept you only need a 
quarter
of the circle, with only 90 holes.

If you need more precision, you can either drill more 
holes,or use more microswitches conected in parallel , 
with the apropriate offset .

On the counter side, a relay apply the inpulse at the + 
or - input of the counter when the rotor is running one 
way or other.

There is one problem whith this system:as the inpulse wire
from the antenna is long, it also bring static impulses,
(or RF?)and block (crash) the counter.I think it could be 
easily resolved using shielded cable or some isolation 
device(or other counters like mechanical or LEDs ones).

I hope this will help ,it may need some improvement but
have the advantage to be simple and cheap with good 
precision. 


Good luck!

73 , Fred, 
CU8AO

 



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