ATHENS 
MY WEATHER STATION, BY DIMITRIS
Location: Peristeri of Athens, Greece
Position: 38 00.58' NORTH / 23 42.04' EAST
Elevation: 63 meters
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First version Fan aspirated radiation shield
I have made a fan aspirated radiation shield for the temp-hum sensor,so as to test my Stevenson Screen. I observed that at night the temp in the radiation shield was 0,4c to 0,8 c less than the Stevenson screen, but during the day the sun was rising the temp 0,2 c- 0,4 c higher than my Stevenson Screen. Both the radiation shield and the Stevenson Screen have a fan.Then i performed a second test without a fan at both radiation shield and the Stevenson screen,and i observed big differences during the day with the sun,the radiation shield gives higher temperatures about 2 c - 2,5 c higher than the Stevenson screen.I thing here in Greece,the radiation shield works correctly only if it has a fan.

I take 11 dishes for flowerpots,but finally i use 8 for them,6 flowerpots 22 cm diameter and 2 for the roof 27 cm diameter I open in the center one big hole 11 cm diameter for the plastic tube PVC with fan,and 3 small holes I take 1 meter big screw 5 mm diameter and i cut 3 pieces 30 cm..
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And i start to put the dishes like photo,i put small plastic tube 3 cm between the dishes. Here i put a fan 12 Volt on the top PVC plastic tube 10 cm diameter and 20 cm length.. And here all the PVC plastic tube i put it inside at dishes .The fan sucks air from the side of sensor out-temp -hum,and air flow go above on the roof.
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And the fan is allready ,after i put 3 cm plastic tube in the screws for to put the one dish to the roof . Here i put the one dish at 27 cm diameter and i do holes for to pass the air flow from tha fan ,and after i will put the end a dish for the roof ,the distance between the dish and the fan is 3 cm. This is allready
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This is the down side with sensor temp-hum.The distance bettwen the above side at out remote sensor with the under side at fan it is 1-2 cm. I put one white corner 25 cm x 20 cm diameter for to put it outside And outside near to the Stevenson screen.Both of them it is 2 meters above the ground
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The fan power source(12V/1A), with 1A glass fuse and on/off switcher with remote.
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Second version Fan aspirated radiation shield
I have made and another two fan aspirated Radiation shield for to make and another test ,the differents from the old is : i added and another dish for flowerpots on the roof ,and i have open more big hole at center of dishes 114 mm,for do not touch the tube 100 mm diameter at dishes.And i have more photos with details how i touch the fan over to plastic tube 100 mm diameter.The general design is the same with the old Radiation shield. I observed the diferents bettwen at first with the new second and third radiation shield it is little 0,2 C - 0,3 C less from the first.I try it and 2 meters over to to my roof ,but at corner over there not at center,and the results it was almost tha same like 2 meters over to ground.

With a hole saw with a rotary blades i open the big holes 114 mm diameter,at center of 6 smalles dishes 22 cm diameter. Here i open the small holes for to passed the
big screw 5 mm diameter.
Here i cut 2 pieces aluminium,and i make a corner for to tuch the fan over to plastic tube.
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Here i open 2 holes to every aluminiun piece Here i have put the one piece aluminium over to plastic tube,and i am ready to put and the other. Here i will cut the 4 angles from the down side at fan ,for to put the down side in the plastic tube.
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The 4 angles from the down side at fan it is cut The fan is already over to plastic tube The fan is already over to plastic tube for the second Radiation shield.
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Here i have put one big dishe 27 cm diameter and i have open holes,down it is the fan. Here i have put the 2 big dishes 27cm diameter,and one white angle bracket 25 cm x 20 cm diameter And here i have put and the third dishes,and i have cut little the dishe for to go little down from the white angle bracket
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Here is all ready ,i have put warm silicone over to screws on the roof ,for do not put inside water from rain,and between dishe and angle bracket. And here i tested the fan with 12 volt DC.The 2 inside screws is for to touch over there,the out remote temp/hum sensor And from the down side image
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Here is and two-third already,at third radiation shield at right side,it want warm silicone over to screws Here it already and two of them ,i have painted a special white color, for to protected the plastic dishes from the UV sun radiation Here it is the metal objects,except the big screw 1 meter size,and 5 mm diameter,and the white angle brackets 25 cm x 20 cm diameter,and the other from down side 12 cm x 9 cm .Here it is 3 angle brackets 40 mm x 40 mm diameter,17 washers with hole at center 5 mm,12 nuts 5 mm diameter, 3 lock nuts 5 mm diameter,2 bolts 0,3 mm x 15 mm lenght together with 2 washers 0,3 mm, and 2 nuts 0,3 mm, 11 bolts 0,3 mm x 10 mm lenght ,and 20 washers 0,3 mm hole at center ,and 11 nuts 0,3 mm ,and one bolt 0,4 mm diameter x 10 mm lenght ,and 2 washers 0,4 mm hole at center
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For better stability to iron tube, i decided to put and another smaller white angle bracket 12 cm x 9 cm at down side the radiation shield, and from the side to radiation shield i make a 90 degrees angle with it ,and i touch angle bracket bettwen radiation shield with 1 bolt with nuts. Click here for you see video.
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Third version Fan aspirated radiation shield
I have made a third version fan aspirated radiation shield,because at older versions I had put the PVC with fan from above side,and it was little difficult if i want to change the fan,it should to put out the third dishes from above,and i build a new version with the PVC with fan to put in the dishes from the down side with 3 locknuts and easy put out it with 3 locknuts,and put out all PVC with fan.And i made a change at third version at first big dish over the fan i open with a hole saw with a rotary blades a hole 68 mm for the fan to go away more easy the air I will not show all the work because the steps is the same like old versions,but the work with PVC tube,and the fisrt dish over the fan.

Here i put 3 angle brackets to PVC. Here i had cut at 4 corners at the fan and i put all inside the PVC,and i keep it with PVC with 4 screw and nuts Here i make a change at old versions at first big dish over the fan i open With a hole saw with a rotary blades a hole 68 mm for the fan to go away more easy the air
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Here i have put the pvc with fan inside to small dishes,and i will put the first big dish over to fan Here i have put the first big dish over to fan. Another one view.
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Here i make a test with anemometer for i see the correct air suck fan,the air speed for correct results must is about 9 - 10 km/h at lenght pvc 18-20 cm . Downside view. Here i have put warm silicone over to screws
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Here it is ready,i have painted a special white color, for to protected the plastic dishes from the UV sun radiation
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