Wiring Error

See if you can spot it:

FCC new seal
FCC new seal

Somehow I missed this one when it first circulated last July. I think I was out on the lake fishing or something.  I suppose a bunch of lawyers would not know the different between a correctly wired antenna and an incorrectly wired one.

Another one:

Department of Jammed Gears
Department of Jammed Gears

If only these were some sort of clever fake, a spoof or something like that.  But no, this is the real deal.  The Department of Innovation’s best work is a logo of jammed gears.  I wonder how much that cost.

Andrew A909D type 78AGM 3 inch connector

I figured if I have this problem, someone else probably has it too.  We have a backup antenna on one of our towers.  The station has a TPO of 28 KW, which is starting to get into the semi serious level.  This antenna is connected to Andrew 3 inch heliax that was installed in 1971.  It has a spiral inner and outer conductor, which is no longer made by any manufacture of heliax.

We completely rebuilt the transmitter site a few years ago, moving a lot of things around.  One part of the project was installing a coax port on the wall and moving all coaxial cables to that entrance.  The main antenna is connected to Cablewave H50J coax.  I ordered a new connector for that transmission line, no worries.  When I cut the back up transmission line, I figured I could re-apply the old Andrew connector.

Andrew A909D type 78 AGM 3 inch coax connector
Andrew A909D type 78 AGM 3 inch coax connector

That is all fine, however, I removed the connector without reverse engineering it, that is to say, I didn’t pay close attention to how the inner and out conductors where cut, or how the jack was cut back.  I will have to reverse engineer the thing now.

Here are the steps I followed:

  1. Check out the CommScope – Andrew website for documentation.  A search shows they only have the current connector, which is nothing like this one and will not work with spriral conductors
  2. Call Andrew and spend many minutes on hold or explaining to various helpers what I want.  I was met with a universal “That is not an Andrew Part number,” or “Gee, I wish I could help but…”
  3. Take the thing apart and begin measuring stuff with a ruler.  Write everything down and draw out a diagram.
  4. Trim off the excess cable then practice putting the thing together once.
  5. Make the final cut and put the re-used connector back on the Andrew transmission line.

You can skip steps 1 and 2, since I already did them for you.

A few things to note:

  • The inner and outer conductors should be cut flush and as close to perpendicular as possible.
  • The inner conductor slug has a left hand thread.  This makes the slug tighten against the bushing.
  • The outer jacked is cut back about 2.5 inches
  • Place the EIA flange on the cable first, then thread the back nut onto the outer conductor, then thread the rubber gasket onto the outer conductor.  The gasket is a tight fit, use petroleum jelly to lubricate it.  This is a gas block connector, so special attention is needed with the gaskets.
  • The inner conductor has triangular pieces 1/8 inch deep cut around the diameter, the depth of the inner slug is critical to the connector going together correctly.
  • The inner conductor is folded inward over the end of the slug.  Bushing, dielectric spacer and EIA bullet is connected to the inner conductor slug and snugged down with a standard screw driver
  • The outer conductor is nipped 1/8 of an inch around the diameter
  • The outer conductor is folded outward over the collect ring
  • Use some petroleum jelly on all the O rings
  • Carefully screw the connector together
  • Final tightening requires a special spanner wrench or attachments for a socket wrench.  The tower crew had these in their shop.

If you have a spectrum analyzer, check it’s return loss and see what it looks like before slamming a full load on it.  If not, turn things on and bring them up slowly.  Feel the connector to make sure it is not getting warm.  If there are problems, heat will be the first warning sign.

3 Inch coax patch panel
3 Inch coax patch panel

Once together, I ran the the transmitters for a combined output of 10 KW and got about 50 watts return, which much the same as it was before.

Towers in the fog/repeating geometric shapes

For no other reason than they were there, I took a few shots under a couple of 300 foot self supporting towers.

300 foot self supporting communications tower in fog
300 foot self supporting communications tower in fog

This tower has a UHF slot antenna on the top of it fed with 6 inch hard line.

280 foot self supporting tower
280 foot self supporting tower

Tower next to the first one. Both can be found on North Mt. Beacon, NY, about 1,800 feet AMSL.

What is the deal with those FEMA/DHS AM backup transmitters?

Back last February, it was reported that FEMA/Department of Homeland Security was mysteriously constructing prepackaged AM transmitter buildings at various PEP (Primary Entry Point) transmitter sites across the country as something call “Primary Entry Point Expansion.”  These buildings contain a 5 KW Nautel AM transmitter, EAS gear, satellite equipment (the exact equipment list is undisclosed) and a backup generator all in a shielded (Faraday Cage), prefabricated building placed inside of a fenced in compound at the station’s transmitter site.  The buildings are being put in place, but not connected to anything in the outside world.  They are planning to have about 80 (the number keeps increasing) of these structures in place when the project is completed by mid 2013.

FEMA/DHS IPAWS expansion project
FEMA/DHS IPAWS PEP expansion project

Why, inquiring minds want to know, would they do that?

The new buildings and equipment are, of course, not provided to the government for free.  I would estimate each unit costs at least $200,000 based on the following:

  • A new solid state 5 KW AM transmitter costs $50-55K
  • A new 35 KW generator costs $23K
  • A new, shielded communications structure costs $70-85K
  • Misc racks, equipment, wiring, shipping, installation costs, fuel tanks, fencing, etc $40K
Those prices are roughly what a private company might pay, the government procurement costs would be higher.  Multiply by 80 and it equals at least $16M, perhaps double that when project administration is considered. In the distant past, through something called the Broadcast Station Protection Program (BSPP), FEMA did provide generators, fuel tanks, transfer switches and occasionally a bomb shelter to key EBS stations throughout the country.  In the recent past, FEMA and the government in general has been reluctant to fund even mandated changes in the EAS system, first in 1997 when EAS was first implemented and again in 2011 when the CAP modifications were mandated.  Why are they now spending at least $16M to provide EMP hardened facilities for AM radio stations?

The rational for this current wave of government generosity, as reported in several industry periodicals, is simply a matter of supplying in depth backup facilities in accordance with Executive Order 13407. The design of the structure and manner of installation seems to indicate the main concern of FEMA is some type of Electromagnetic Pulse (EMP).  If an EMP were to happen and it took out the station’s main transmitters, these could be connected to the existing antenna system and switched on.  They would provide emergency programming and interface directly with FEMA’s IPAWS (Integrated Public Alert and Warning System).  No mention at all of the station licensee’s ability to use these facilities, only FEMA.  It would seem that the licensee would be excluded from using their own frequency if these “backup” transmitters were put into use.

The interesting thing about this is that there is a coincidence with the upswing of solar cycle 24.  Back in 2008, likely when this project was likely first dreamed up, the predictions were for a great number of sun spots in this cycle.  That has not happened and in fact, this cycle in now predicted to be the weakest solar cycle since 1823.  Even weak sun spots cycles can create problems, but does that warrant supplying 80 backup transmitters, generators, fuel tanks and buildings to various AM broadcasting stations throughout the country?  Further, solar flares and Coronal Mass Ejections (CME) are fairly slow moving events, the sun is well monitored; alerts would be issued and precautions taken.

The story doesn’t add up, but it is difficult to say exactly why.

One other thing to consider: HEMP (High altitude Electromagnetic Pulse from a nuclear air burst).  AM transmitters are more robust when it comes to HEMP than FM transmitters are.  This is because of their modulation type and frequency of operation.  A 5 KW AM transmitter can withstand RF voltages six or eight times it’s name plate carrier rating.  Tube type transmitters are even more robust than solid state.  The FM broadcast band falls right in the middle of the HEMP fast pulse frequency (72-225 MHz), which will likely resonate in the tuning circuits of the transmitter exposed to it and destroy all of the active devices.  Not so with AM transmitters.

A HEMP event would cause catastrophic damage to the electrical grid across wide areas of the continent (see also;  Starfish Prime). The voltages instantaneously induced on computer circuit boards and power supplies would be so high, they would likely burst into flames if they were close enough to the detonation.  The same for almost all other electronic devices with circuit boards.  It would set the country back one hundred or more years, technologically, causing massive disruptions in the food supply chain.  Such an act would surely be met with massive nuclear retaliation by the US.  The military has not only hardened all of it’s communications and command facilities, they have undergone rigorous EMP testing, finding and fixing design flaws.  Thus, the US military’s capacity to wage war would continue undiminished after a HEMP event, a fact that all other members of the nuclear club are surely aware of.

Who, in their right mind would launch such an attack?  Nobody.

In the light of current government trends where the FBI engages in a one year sting operation on a Amish farmer selling raw milk, the Bureau of Alcohol Tobacco and Firearms is running guns to Mexican drug cartels, The US Department of Education employing its own SWAT team to serve warrants for delinquent student loans (they say no but offer no other explanation), Gibson Guitars being repeatedly raided for improperly labeled wood products,  and so forth, makes me wonder what the government is doing.

Ponder this:

“Take care, sir,” cried Sancho. “Those over there are not giants but windmills.”

Or are they.  We need to start asking more questions.