SteppIR failure (again!)

For the second time the 3-element SteppIR antenna at SEØX failed, this time with terrible timing a few days before the SAC SSB Contest. First I expected the failure to be similar to when the antenna copper tape jammed inside the EUH the past winter. Friday night, less than 20 hours before the start of the contest, we took the tower down and opened up the dipole EHU to find the drive shaft broken. Accepting the fact that the SteppIR would be grounded for the contest, I started to think about alternative antennas but possible replacement antennas would never provide a signal similar to the SteppIR so instead I re-focused my thoughts on how to temporarily repair the EHU. Looking closer at the shaft assembly I realized that the plastic shaft had not entirely broke into parts, it was actually still sitting on motor shaft but not able to move as it had broken where the lock pin is attached. With glue and cable ties I was able to fix the platsic shaft in place and hold it tight, so that the mechanism worked as intended (see photos).

Broken SteppIR shaft before repair

Fixed SteppIR shaft after repair

Fixed SteppIR shaft after repair

With just a few hours left to start of the SAC contest, this was encouraging progress and a test run on the floor confirmed that it worked fine. But having the shaft stay in one piece with the tapes running in glassfiber pipes rocking back and forth in the wind is another thing. The dipole was assembled on the antenna, and the tower went up in the air again. A test run confirmed the tapes where moving as intended and SWR readings where similar to before the breakdown.

Happy to have a working SteppIR I put the station on air and worked around 1000 contacts in the contest without the shaft failing on me, most contacts on 20 meter but with several band switches between 20, 15 and 10 meters and heavy use of the 180/Bi-dir functionality during the runs. Suspecting that the calibration procedure would put extra pressure on the shaft, I did not dare to calibrate the antenna during the contest.

A refurbished EHU is now on its way to Stockholm to replace the one with the broken shaft, so hopefully this will be the last time the SteppIR have to be repaired the morning of a contest.