CGC #1110

by CGC on December 12, 2011



                      THE CGC COMMUNICATOR

                            CGC #1110

                   Monday,  December 12, 2011


                Robert F. Gonsett, W6VR,  Editor

    Copyright 2011, Communications General® Corporation (CGC)



  o  FEMA to begin weekly EAS-CAP tests:

  o  The FCC Commissioners are set to meet Tuesday to consider
  implementing the CALM Act (eliminating loud TV commercials):

  o  "In this Order, we [the FCC] take procedural measures
  to ensure... that the environmental effects of proposed
  communications towers, including their effects on migratory
  birds, are fully considered prior to construction:"



  A Notice of Violation has been issued to Raytheon in Fullerton, CA, 
for failure to notify the FCC of a change in ownership of a tower 
structure and failure to post the Antenna Structure Registration 
Number as required.

                           RANDOM NOTES


  The dinner is Tuesday, December 13, at 6:30PM at the Holiday Inn 
Media Center in Burbank, RSVP required:



  A major radio station in the Los Angeles area was off the air for 
22 hours during L.A.'s big windstorm.  The station had a power 
generator but -- just before the storm -- was asked to disconnect 
the generator because it did not have the required air pollution 

  The agency making the disconnect request was the AQMD, the Air 
Quality Management District.  The station got back on the air with 
some consternation by renting an AQMD-compliant generator.

  Editor's comment:  This is another example of why we need a smaller 
government.  Air pollution caused by rarely used emergency power 
generators is insignificant compared to pollution caused by many, 
many other sources.

  "My reading of history convinces me that most bad government 
results from too much government."  - Thomas Jefferson



  o  Future technology to see at the NAB Show in Las Vegas:

  o  Veteran broadcaster John Lynch takes the management
  reins at the San Diego Union-Tribune:

  o  Copper theft darkens the night lights at San Diego City
  parks.  "In 2009, [copper] was valued at $1.25 a pound.  The
  value is now up to $4.00 a pound at many salvage yards:"

  o  Copper thieves prey on church heating and A/C units:

                   THE KSCI(TV) ANTENNA UPDATE


  Following is an invited letter concerning the failed
  KSCI antenna structure.

  "I went through and reviewed the pictures [in CGC #1108] and the 
failure most definitely appears to have occurred in the extension 
mount pipe and not in the antenna.  [In your newsletter, the 
extension mount pipe is referred to as a "monopole."]

  "I reviewed our archives and the antenna was manufactured in 2000 
by Andrew and installed in 2001; however, the extension mount pipe 
was not supplied by Andrew.  It was designed and manufactured by 
another firm.

  "Also, as we had briefly discussed, ERI acquired Andrew broadcast 
in 2003.  ERI now designs and supplies custom mounting solutions 
for all of our antenna product lines including UHF TRASAR arrays 
such as this, and we are actively working with KSCI on a replace-
ment system.  Please feel free to contact me if you need anything 

  James M. Ruedlinger, P.E.
  VP - Structural Division
  Electronics Research, Inc.
  JamesR (at)



  As we said in an earlier newsletter, antennas falling off broadcast 
towers are very rare; hence, the unusual interest in the KSCI case.  
Engineers have brought two other notable California antenna catas-
trophes to our attention and they are worth mentioning here.

  The first case involved the VHF-TV antenna for KNTV, the NBC 
station in San Jose.  The antenna itself broke and toppled during 
the Loma Prieta earthquake (magnitude 6.9) in 1989.  A consulting 
radio engineer familiar with the case said, "Everyone was surprised 
that the antenna failed not at the flange or in the middle of the 
tube, but just above the weld...."

  A representative of the antenna manufacturer indicated that the 
tower and antenna were never engineered to work together 
mechanically as a unit.  According to his report, the KNTV antenna 
was mounted atop a guyed tower but the top guys were some distance 
down from the top of the tower structure so the upper section of 
the tower and the antenna oscillated together during the earthquake.  
During the rebuild, guy wires were brought to the top of the tower 
to give the new antenna a more rigid platform.

  The second case involved the collapse of the KWIZ-FM monopole tower 
in southern California some years ago.  However, the antenna did not 
fall off the monopole -- the monopole reportedly fell over and took 
the antenna with it.  What is notable is that the monopole failed just 
above the base flange.



  The fallen KSCI antenna gives us a good opportunity to explore some 
colorful names that apply to broadcast antennas in general and their 
mounting structures in particular.  The interesting feature we will 
explore today is the open lattice portion of the KSCI antenna 
structure highlighted in the following photo:

  This open lattice portion is sometimes referred to as a "milk 
stool," "bird cage" or "wedding cake."  It sits between the antenna 
(descending to the left) and the monopole (rising to the right) and 
is built with heavy gauge steel.

  Put simply, the milk stool gives easy access to an end-fed 
antenna's coaxial input port and allows the transmission line to 
be routed outside the monopole for easy servicing and inspection.  
These photos show the situation more clearly from various points 
of view:

  By the way, the grated platform sticking out from the milk stool 
wasn't put there for the benefit of tower climbers; the "platform" 
is actually an ice shield designed to slice and dice falling ice 
so it won't damage the exposed transmission line.
Falling ice is a serious concern at high altitude sites such as 
Mt. Harvard.



  Following is a question and answer session with Dave
  Jurasevich of the Mt. Wilson Observatory that is located
  immediately east of the Mt. Wilson broadcast complex.

  Q. The KSCI(TV) antenna on Mt. Harvard reportedly collapsed at 6:30 
AM on Thursday, December 1, 2011.  Could you possibly send the CGC 
Communicator wind speed data from the Mt. Wilson Observatory for that 
time plus and minus 12 hours?

  A. It was fortuitous that a day or so before the windstorm started 
the USFS put up a RAWS weather station at the Observatory.
If you click on this link...

...and click the "Past Data" link on the left side navigation bar, 
you'll be able to retrieve the RAWS data for December 1st and 2nd, 
the days with the highest winds.

  For Dec 1st, the 5:30 AM Mount Wilson RAWS site recorded the 
maximum wind gust at 40 mph out of the NW and at the 6:30 AM 
recording time the maximum wind gust was 34 mph out of the N.
Perhaps the winds were higher at Mt. Harvard to collapse the 
TV antenna.

  Q. About how high above ground is the Wilson anemometer and
  is it shielded by trees or structures?

  A. As with many RAWS stations, the anemometer on this one is about 
6+ feet above the ground.  There is some shielding from a tree to 
the north but the RAWS station is in a fairly open location.  The 
[person] who sited the equipment checked the Observatory and felt the 
current spot was the best location for the station.

  Q. Did you have any damage or unusual episodes at the Mount Wilson 
Observatory that could be shared with our readers?

  A. I didn't notice much damage at the Observatory.  There were lots 
of small branches down and a few other minor mishaps but in general 
the Observatory did pretty well.  Where I live in Alhambra [we] had 
quite a number of big trees down, including one on my street that 
completely blocked the road.
We (Alhambra) were without power for 40 hours in my area.

  Dave Jurasevich, Superintendent
  Mt. Wilson Observatory
  December 9, 2011

                       THE MT. WILSON REPORT


  Here are a few important notes that come to mind:

  o  During and after the big windstorm, we all ran on
  generators for 61 hours.  I recommend an oil sample test
  to really see what your engine is doing inside.

  o  More bad weather is on its way Sunday with the possibility
  of a foot or more of snow.  Roads could close, so be ready.

  o  The water tank is at 16 feet and dropping.  Not a good
  situation.  USDA Forest Service needs to fix their well pumps.

  o  Make sure to update your generator logs.  AQMD is always
  lurking.   ;-)

  o  Obviously, don't forget to winterize your sites.

  Cheers, Dennis Doty
  dennisd (at)
  December 10, 2011



  Mt. Wilson is currently receiving its electric power from a 16kV 
circuit provided by Southern California Edison.  This is the 
"backup" feed to the mountaintop and was used while the main 33kV 
circuit was being repaired (wind damage, broken cross arm).
Both feeds are converted to a common voltage for distribution to 
users on Mt. Wilson.

  Mt. Wilson will be switched back to the 33kV circuit as its primary 
power feed at 1:30AM on Tuesday, December 13, 2011.
There will be a 30 second power outage (time approx.) when the manual 
switch occurs.  (If you time the outage, please let us know the 
results.)  The 16kV circuit will then be used as a hot standby for 
Mt. Wilson.

  The situation is very different on Mt. Harvard.  There, the 16kV 
feed is the one and only feed so there should be no power 
interruption when the circuits are swapped at Mt. Wilson.
"Should" is the operative word.

  After Edison rebuilt the Harvard circuit, Harvard reportedly lost 
the ability to be back-fed with power from the 33kV circuit should 
the 16kV circuit fail.  At the SCFCC picnic, SCE said they could 
perhaps come up with a quotation for devising a back-feed, but we 
have heard nothing further.  Sounds like a Harvard user needs to 
make a formal request before anything will be done.

                       EQUIPMENT FOR SALE


  I have the following equipment installed three years ago at 
Pleasants Peak, and is now no longer required.  It is available 
cheap and going fast:

  o  Two - 6 ft Ku band heated satellite dishes with LNB,
  $100 each or best offer.

  o  One - complete VSAT - 1.2 meter dish, TX PA, LNB, indoor
  terminal for service $200 or best offer.

  o  One - Dielectric brand dehumidifier $150 or best offer.

  We also have 100' of 3-inch hardline with connectors and
  a 10 dB antenna for 716-722 MHz (TV Channel 55) for sale at
  scrap prices.

  Fred Daniel
  (949) 640-8899
  FredDaniel (at)
  December 8, 2011

                       LETTERS TO THE EDITOR


  Letters to the Editor of the CGC Communicator should be posted on 
the Tech Letters Website at the URL below.

  If you are a registered Tech Letters user, post your letter via 
email to Steve.  All letters and comments are moderated and are 
posted after review.  Also contact Steve if you have trouble 
viewing or posting:

  sblodgett (at)



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