OBSERVATIONS FROM NORWAY.
 17-04-07.
 ADJUSTABLE AERIAL CLAMPS.


Regarding my recent posting about operating from a mountainous area I received an e-mail from a station in Texas requesting information about where I'd purchased the adjustable clamps on the 70cm aerials ... because the station in question required something like this for field day use. (see pic).

 

The LA2QAA array on a nice day.

                           


In fact, these clamps, like the rest of the array ... (with the exception of the "El Cheapo" TV rotor) ... were homebrewed, just bits and pieces from the junk-box, but they do give me the opportunity of being able easily adjust the vertical radiation angle of the aerials on the crossboom ... which, incidentally, is a bog-standard broom handle covered with plastic electrician's tape.

Nota Bene.

It's IMPERATIVE! that BLACK plastic tape be used ... since any other colour will affect the SWR dramatically! ... though GM1SXX swears this effect can be minimised by using light battleship grey instead ... (opinions from other operators are invited).

For those wishing something similar for field day use, the following sketch is self explanatory.


                  

Clamp Details

            
Each clamp comprises a strip of aluminium bent at 45 degrees, a wooden block, a car exhaust clamp and two wing-nuts.

For field day ops I use an ordinary musician's microphone stand, the upper part used as the crossboom, with the UHF aerials mounted on the boom. This make it easy to twist and turn the aerials to follow the path of a LEO on it's orbit from horizon to horizon using just one hand. It's more effective and far easier than doing the "Arrow Dance".

73 John.   <la2qaa@amsat.org>