WA5IYX 2013 TV-FM Antenna Repair Saga



Background

The very old Rohn 6 (old even when I obtained four pieces of it in Jun 1970 from W5QDB/N5TX [SK} 
for $45) was never put to its first-intended purpose of supporting my 50-MHz Yagi due to the fact
that there was no top section.  One section had some leg splits from freezing water and it would 
have been used in the in-concrete portion.  They spent several years stored in the garages and/or
backyards of the two QTHs spanned over those many years since I first got them.                  

In Nov 1981 a section (NOT the freeze-damaged one) was taken back to N5TX to see if they could   
fabricate some sort of tapered top section for it.  I last saw the results of those attempts     
in the parking lot while there during the hosting of KH6IAA's May 1982 visit to town.  It all    
probably disappeared before/when Tex closed his business site down a couple of decades later.    

Later, in Sept 1988 with H. Gilbert approaching, that damaged tower section was utilized to      
bolster (with 25-lb cinder blocks between the rungs) the north side of my telescoping mast by    
angling against it at the eaves.  That mast was a 1964 gifted 50' one (which was only extended to
c. 20' due to its having the flange from a bent mid-section removed) which here has held my 5-el 
50-MHz CushCraft and 3-el 28-MHz Wilson Yagis since the mid 1970s.                               

That left the two good 10' Rohn 6 sections to wander about the backyard for the next two decades.

In late 2008 I got a Bolin Phase Box to try to contend with local HD sidebands, LFPMs, and       
translators.  For that to be effective I had to erect another FM-6 antenna at some distance from 
the old, 1977-installed, one.  As there was no convenient space left on the roof for such, a site
in the backyard was chosen.                                                                      

A Rohn 6 section was utilized with a 20' telescoping mast (originally used from Mar 1973-Aug 1980
to support my TV-FM antenna stack until an F0 tornado on Aug 10, 1980  bent the top section at   

(in background)

the roof line and required its replacement.  That meant constructing two plywood plates with     
1.25" holes to go over the three tower legs and another much larger one for the mast to extend   
thru - with clamps to prevent its rotation.  A combination of L-brackets, pieces of 2x4s, and    
bolts were used to secure the three tower legs to another larger baseplate of plywood which would
be weighted down with cinder blocks, etc.                                                        

Jul 16, 2009

In Sept 2010 the winds from TS Hermine here swung the adjacent neighbor's ligustrum tree branches
(which had been trimmed back by me for decades) far enough to damage my 1973 V-100 on the east   
end of the house.                                                                                

Sep 9, 2010


Sep 9, 2010


Sep 9, 2010


Sep 9, 2010


Sep 9, 2010

A HD-5030 was obtained, and rather than replace the V-100 with it (and still be in risk of that  
ligustrum tree) it was added to the FM-phasing antenna system.  (The neighbor then soon removed  
that entire ligustrum tree!)                                                                     
 

Oct 2, 2010
(arduosly raised by hand - no come-a-long used)


Oct 2, 2010

Then 2013

All went well until 50-60 mph n.w. winds struck on Feb 25, 2013 - which toppled the Rohn 6 system



(the bottom plywood base had rotted out unobserved - the fallen 8-ft landscape timbers were only
leaning against, but NOT attached to, two tower side rungs and so easily slipped off)

It fell into/thru the adjacent loquat


Feb 27, 2013

In manuevering it free with a come-a-long





resulted in damaged elements on both antennas.


Feb 27, 2013


Mar 11, 2013 - removed damaged HD-5030

Mar 11, 2013 - removed damaged HD-5030

Replacements were ordered - an FM-6 from Solid Signal via FedEx arrived in damaged condition -   
unnoticed at first while still boxed, so another (from Summit Source) was obtained.              


damaged new FM-6


damaged new FM-6


damaged new FM-6


FM-6 damaged box end (FedEx)

Then began the LONG task of reconstructing the base mount plywood segment.


detail of one L-bracket pair mounting for Rohn 6 leg - Mar 11, 2013


bottom of Rohn 6 with 2x4s on each leg to mount to plywood base - Mar 12, 2013


completed wooden base of Rohn 6 - Mar 15, 2013


wide view of Rohn 6 (WIP) w/o antennas - Mar 15, 2013
(landscape timbers are NOT attached yet)

The lowering/raising of the system required two come-a-longs (anchored to trees).  Getting it to 
a proper position to remove/install the antennas needed the use of a step ladder (to support the 
mast) and a large (3-ft square) plywood platform bolted to 4 stacks of 3 cinder blocks (they     
themselves bolted together) for me to safely stand on to reach things.                           


03-27-2013 - top end of Rohn 6 system with damaged antennas removed
and ready to attach the new set to the rotor mast


Rohn 6 with antennas - resting on step ladder - Apr 4, 2013


Rohn 6 with antennas - resting on step ladder - Apr 4, 2013


Rohn 6 with antennas - partially raised - Apr 6, 2013


Rohn 6 with antennas - partially raised - Apr 6, 2013


Rohn 6 with antennas - erect in temporary location - Apr 6, 2013

After that erection the rotor didn't work.  I had to bring the control box outside, break the    
4-wire cable to use it to see what was going on.  One wire had pulled off the screw in the rotor 
housing - so it all had to be lowered, fixed, and raised again!                                  


Rohn 6 with antennas - lowered again to rest on ladder (to fix rotor cable)- Apr 7, 2013


Rohn 6 with antennas - partially raised again - Apr 7, 2013


Rohn 6 with antennas - raised - Apr 7, 2013

The original full install was too near to my 10-m Yagi tips and had to be shifted away.


Rohn 6 with antennas - raised - but too near 10-m 3-el Yagi tips - Apr 8, 2013


Rohn 6 with antennas - moved far enough away from 10-m 3-el Yagi tips - Apr 8, 2013

This time the bottom plywood mounting plate would be anchored to the ground with 10" spikes as   
well as tower leg angled braces in the form of three hefty 8-ft landscape timbers secured with   
loose sliding brackets to the rungs (and wire jumpers to prevent any ESD RFI).  The same sort of 
spikes were intended to be used thru drilled holes on the timbers' ground ends.                  


Rohn 6 showing three 8-ft landscape timbers attached to tower rungs - Apr 10, 2013


Rohn 6 detail of landscape timber mounting hardware and ESD-prevention jumper wires - Apr 10, 2013

All in all, a somewhat strenuous and prolonged one-man project.

Page Created: Dec 14, 2016