zondag 20 april 2014

Dipole troubles @ OT1A

Troubles on 10Mhz !

I keep it in my calendar to do a big review of my outside equipment every two years.  Normally this is summer stuff, but with the good weather of the moment and a free day on Friday I decided to do it now.

This gives me some extra time this summer to play on 10Mhz in order to achieve DXCC band  8.  With only 32 countries confirmed it will be a big job...

Four things to do :
1- line up the dipole which has turned 45 degrees by the hard wind some months ago.

2- check the wiring of the Steppir and clean the fiber tubes (a lot of pigeon shit this year).

I also remarked the results of our hard working sun.  Fibers are suffering the UV light.
Step 1 : the green painted fiber becomes grey.
Step 2 : all painting disappears and the main fiber becomes visible.

I do not estimate any risk on this process.  If needed, fibers can be changed very easily.

The 12 wires of the 3 stepp-motor were in perfect condition.
This antenna is now working fine for about 7 years in all conditions without one single failure.  Super FB !!

3- check the wiring of the Yaesu rotor. The needle doesn't follow, so maybe a bad connexion.
I've found indeed two wires with corrosion.  My plastic protection egg - vertically mounted - wasn't 100% water proof.  Now I've mounted the egg horizontally (like my steppir egg).

This is the risk of having an extra connexion near the rotor.  It helps a lot if trouble appears - the control cable can be checked end-to-end very quickly - but the risk for corrosion increases.

4- rebuild the 40m Optibeam dipole into the 30m version by replacing some tubes.
At this point Murphy joined the club.  The changing was an easy job.  In order to be sure, I did a dummy-load test and the antenna feed point to check the coax.  No problems.

 But once back on place in the air, the antenna gives me a full-scale swr...  Damn !  
Or there is a problem at the feedpoint, or there is a problem with a bad connexion between tubes.  Anyway after all work I can't come out on 10 Mhz...

 I will go for another solution i.e. making a vertical dipole.  This will be easier on short term.

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