[Fourlanders] EME Antenna Workday Report

[Jim Worsham]

Any postmortem yet on what happened to the elevation rotator?

73
Jim, W4KXY

Sent from Mail for Windows 10

From: Bob Lear
Sent: Thursday, February 1, 2018 8:29 PM
To: FourLanders Contest Team
Subject: [Fourlanders] EME Antenna Workday Report

At the end of the January contest, when we made 14 2m EME Q's using 
Johnny's 2m station in my shack, the elevation rotor froze up on us.  
Just quit and stuck at about 20 degrees elevation.  Azimuth still worked 
OK.  We couldn't move the rotator manually like we usually can so 
something major is wrong, jammed gears or something.

Anyway, since Johnny wanted to be ready to try to work the upcoming 
Bouvet Island DXpedition on 2m EME, we needed to get it fixed.  The 
elevation rotor has the cross-boom through the rotor itself so it's not 
an easy job to work with that having 21' boom cross-pol yagi antennas on 
each end of the 12' cross-boom.  When Johnny and I put it up, we 
determined that it was definitely a 3 man job!  I thought of a way to 
take the rotor out and replace it without having to completely 
dis-assemble the entire set up.  But I also thought that it was at least 
a 4 man job to do this properly and not cause us any more physical labor 
than necessary.  We decided on Tuesday January 30, even though it was a 
pretty cool day with a mild breeze but we were also running out of 
time.  Rick KK4LPP and Sherman W4ATL offered to come help Johnny K4SQC 
and I do the job.  With my back problems, I volunteered to be the ground 
go-fer!

I have a bunch of masonry type scaffolding and we set up two sections 
high on each side of the tower trailer, lowered the antennas as low as 
the mast will go and with Rick supplying some extra scaffold walk boards 
and I made some 2x4 upper rest and safety rails.  We don't think we can 
tilt the weight of these antennas over like we do with the contest 
antennas on trailers.  We were able to remove the right side antenna 
with it's fiberglass boom extension, support post and feedline support 
rail from the solid aluminum cross-boom that runs through the rotator 
and rest it all on the safety rails.  Then we managed to slide the rest 
of all the left side antenna system with the cross-boom out of the rotor 
body onto the scaffolding on the other side.  Now the rotor was easily 
replaced and we just reversed our dis-assembly and got it all back 
together.  Probably took as much time setting up and taking down the 
scaffolding as it did to do the antenna work, but it was safe and more 
efficient than complete dis-assembly.  We did the whole job in 2 1/2 
hours but it did take our 4 man crew to do it this way. Probably would 
have taken 8 hours or more for two folks to get it done and I wouldn't 
have been of much help with my current back problems.

I have taken some pictures of what we were doing and Kos has posted them 
somewhere for viewing since they can't be attached going through this 
email reflector.  Check them out at:

http://svhfs.org/pix/IMG_0868.JPG

http://svhfs.org/pix/IMG_0864.JPG

http://svhfs.org/pix/IMG_0860.JPG

Special thanks to Rick and Sherman for coming up and helping us out on 
this venture.  Johnny bought us all lunch!
Later in the evening, we got the 2m station back on the air, antennas 
tracking again and copied sigs off the moon, so success! Didn't try to 
make a Q as Johnny and I were pretty tired by then.

73, Bob


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