October 2011
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National EAS Test

Video available by youtube, courtesy of Radio Magazine:

It is a pretty good simulation of what will happen on November 9th.   The script used is not the actual script that will be used for the national test.

After the test, the video shows how to bail out of the national test in the event that a valid EAN is not received.  This is important information, as this particular failure has occurred many times in the past.  If the LP-1 or PEP station that transmitted the test fails to send a valid EOM, the EAS unit will continue to transmit that station’s programming indefinitely.  If the LP-1 or PEP station resumes regular programming while the EAS unit is relaying their programming over the air, that would be a good indication that the LP-1 or PEP station has failed to send a valid EOM.

Update: Paper work is required.

The ERI LP Rototiller FM antenna

This was in the back room of one of the radio stations we do work for:

ERI LPX2E FM antenna on the ground

ERI LPX2E FM antenna with RADOMES on the ground

It is a burned out ERI LPX2E antenna.  The manager was complaining that it took up too much space and he didn’t know what to do with it.  Could I get rid of it?  Sure, no problem.  I could at least cut it up and scrap it.

When I first looked at it, is seemed complete and undamaged, however, upon further examination it seemed that some of the inter bay line had over heated and one of the tuning sections that goes from the power divider out to the bay was missing.  Therefore, I took it apart and separated the copper from the brass.  Most of the antenna is made from yellow brass, due to it’s hardness.  The inner line sections are copper and the mounting hardware is all stainless steel.  I will perhaps break even time wise, but it is one of those projects that can be done on my time in between other paid work, so it will be fine.

ERI rototiller antenna bay

ERI rototiller antenna bay

I am going to keep one bay intact with the RADOMES on as some sort of modern art project.  My daughter thinks we should install it in the yard as a part of a fountain-fish pond-bird bath contraption.  The idea is to mount the bay facing up as in the picture above and run a hose up the inside of the transmission line to the T section.  A hole will be drilled there and some type of fountain head installed to spray water up over the RADOME.   The system will be run by a solar powered pond pump.  I’ll have to take pictures when it is done.

At a crossroad

This is a situation that is and will be playing out over and over throughout the country as the decay advances. W*** signed on the air in March 1963. I believe this is the original tower:

W??? tower

W*** tower

As you can clearly see from this picture, this tower has several problems. Aside from the loose guy wires, the rust and general structural decay, it is bent in several places.  Currently, the forces are in equilibrium, but for how long, no one knows.  It is certainly not safe to climb.  At 144 feet, it is no longer required to be marked or lit, thus, over the years, the paint peeled, the weep holes filed up, the guy wires rusted and loosened, which leaves us with the situation today.

At the transmitter building, there are other issues with the basement flooding, mold, etc.  Truth be told, this station makes no money on it’s own.  It would cost several tens of thousands of dollars to fix all these issues, and for what; a high end of the broadcast band class D AM station which has not shown up in the ratings for fifteen years.  Once upon a time, it was a surviving, perhaps not thriving, local radio station. Those times have long since past.

The question is; what to do with it.  Sign it off and surrender the license?  Fix all the problems and continue to broadcast?  Donate it?  If so, who would take it?  Or, more likely, wait until the tower collapses and deal with it then.

I’d imagine that there are many others just like it dotting the country.  On the whole, the AM broadcasters that are viable would be better off if this dead wood was cut away and discarded.

Implementing MCDL (Modulation Dependent Carrier Level)

Since the FCC waved some of its rules regarding carrier power and carrier shift on the AM broadcast band, AM stations are now able to implement MCDL or DCC (Dynamic Carrier Control) technology to save money on their electric bills.  This technology has the potential to save tens of thousands of dollars for higher powered AM stations (high power=greater than 10 KW carrier level).

On a standard AM broadcasting station, the carrier represents two thirds of the energy being transmitted, with the modulation index containing the other one third.  The carrier contains no information; it is simply there on the center frequency at the power level authorized by the station’s license.  Thus, if the carrier can be reduced without effecting the quality of the broadcast reception, it will reduce to overall power consumption of the transmitter.  In areas where electric costs are high, the savings can be substantial.

There are various ways to accomplish this.  The first is called Dynamic Carrier Control (DCC), where the carrier voltage is reduced during moderate modulation levels (between 20-50%) and restored during peaks.  This reduces the output power during average modulation, restoring most of it during quite periods and peaks.  The next is Dynamic Amplitude Modulation (DAM), which is similar to DCC.  The most savings will noted with less heavily processed programming such as talk radio because the higher the average modulation density is, the less the MDCL circuit reduces the carrier voltage level.  The little graph in the diagram shows the reduction in the carrier voltage vs. modulation levels.

Nautel DAM block diagram, courtesy of Nautel, Ltd.

Nautel DAM block diagram, courtesy of Nautel, Ltd.

Finally, Amplitude Modulation Companding (AMC) reduces the voltage in both the carrier and modulation product during peaks.  This results in better savings for higher density modulation indexes.  It is also the most transparent of the three schemes, as the carrier is restored to full power during periods of low or no modulation levels. During peak modulation, the reduction does not drop the power level below the un-modulated carrier level.  The little graph in the diagram shows the reduction in the carrier voltage vs. modulation levels.

Nautel AMC block diagram, courtesy of Nautel, Ltd

Nautel AMC block diagram, courtesy of Nautel, Ltd

Nautel has done extensive work on MDCL and includes several algorithms in their NX series transmitters.  For older Nautel transmitter models such as ND, XL, XR and the J-1000, there is an outboard exciter, which is in a one rack unit chassis.  Older transmitters may need a simple field modification to create a DC coupled audio input.  The cost for the upgrade is approximately $5,000 USD, however check with the regional Nautel sales rep.

Once the system has been installed, there are several things to be aware of:

  1. Modulation monitors may not work properly, especially older units, which will show significant carrier shift and have carrier alarms.   Belar AMMA-2 modulation monitor is specifically built to work with MDCL transmitters.
  2. When making field strength readings, the MDCL circuitry must be turned off to get accurate readings.
  3. For stations running IBOC, the amount of carrier power reduction may need to be experimented with, as the effect of the carrier reduction may cause the transmitter to exceed the NRSC mask.

Currently, only Nautel and Harris are selling MDCL transmitters.  I spent several minutes poking around the Harris website and looking through their product brochures for the DX series transmitters and no mention of DCC o MDCL was found.  I’d be happy to include any information from Harris if it were made available.

The melted ground wire

I found this on one of the guy wire anchor points for a 400 foot tower:

#2 solid copper wire burned open by lightning strike

#2 solid copper wire burned open by lightning strike

Had to be a pretty big hit to burn open a #2 wire. This is on one of six guy anchor points for the tower. The ground wire is U bolted to each guy wire before the turnbuckle and then goes to ground. This was noted between the last guy wire and the ground rod.

It is important to find and fix these things, as the next lightning strike on this tower would have a less than ideal path to ground at the guy anchor points, forcing the current to flow through other parts of the transmitter site, possibly through the transmitter itself, to ground.

I generally try to do a brief inspection of towers, guy anchors, lighting, painting and a general walk around the property twice a year.  That helps prevent surprises like “Oh my goodness, the guy wires are rusting through,” or “Hey, did you know there is an illegal “hemp” farm on your property?”  Well, no officer, I don’t know anything about that…

Less than one month until the Coordinated National EAS test

November 9, 2011 at 2pm EST, FEMA will be testing EAS with it’s first ever national level test.  To promote that event, they have released a twenty eight page “tool kit,” (near the bottom of the page) designed to help everyone get through the test.  It should be interesting.  According to FEMA:

The nationwide EAS Test is not a pass or fail measure, nor will it specifically test Common Alerting Protocol (CAP) compliant equipment (although CAP compliant equipment should pass the Emergency Action Notification [EAN] live-code in the same manner as legacy EAS equipment).

They will release a Emergency Action Notification (EAN) to all the Primary Entry Point (PEP) stations, which should then flow down stream through all the radio, television, cable systems, and direct broadcast satellite systems.  The test should last about two minutes and will conclude with a standard EOM.

I doubt very much it will sound like this:

That is WHEN, Syracuse, NY singing EBS test.  A bit of originality there. WHEN played this for their weekly EBS test for the better part of the 70’s.  Naturally, the FCC found out about it and told them to stop.  Shame, really, it is kind of catchy.

If you have some spare time, download the tool kit and study up for the test.

Micro Radio goes to Occupy Wall Street

I read a very interesting article from John Anderson regarding the Occupy Wall Street movements use of media, specifically low powered radio.  Being a native New Yorker, the demonstrations are of some interest to me.  To date, the demonstrators have placed a wide variety of grievances at the feet of “Wall Street,” some justly and some not.  What I found interesting about it is this:

Last week, the Occupy Wall Street encampment established a microradio station at 107.1 FM. The station simulcasts the 24/7 live stream which provides coverage of life inside Zuccotti Park, as well as street-level reportage of daily protest actions in New York City’s financial district.

One of the reasons for this is the City’s ban on use of amplified speakers and or public address systems. By using a micro radio station, persons in the crowd too far away to hear orator can use a small FM radio or even their smartphones to listen to the speech.  Another reason is the idea that large corporate media has been controlling the narrative for far too long, to the detriment of the average citizen.

Zuccotti Park is in lower Manhattan, about two blocks away from Wall Street itself. It is described as 33,000 square feet, which makes it about 3/4 of an acre.  A part 15 FM radio station (47CFR 15.239) can easily cover this area and more.  Even with the station limited to 250 µV field at 3 meters from the radiating element, generally though to be 100 mW TPO,  the reliable coverage area would be a radius of approximately 200 feet, depending on local interference.  That makes the coverage area approximately 125,600 square feet or more.  There are several other stations licensed to 107.1 in the greater NYC area; WXPK, WWZY are the closest and most likely to cause problems.

I am not sure how they are generating their live stream, but when listening to it for several hours over the weekend, I found it interesting and technically well done.  They seem to be running circles around others, who are only grudgingly admitting that there might be something going on in some forty odd cities across the US.

Micro Radio is a creative way to use the available technology and keep the public and protesters informed.

More HD radio news


An interesting take from a non-broadcaster that gets it mostly right.    The premise for HD radio™, as the author states, was to serve two purposes; improve sound quality and add extra programming channels.  I have a few issues with this statement:

Regarding the improved signal, that still holds true, and can be especially beneficial for AM radio, which has struggled for some time with signal degradation.

I would argue the opposite. HD Radio™ has done nothing to improve the signal quality of the AM band. It has, in fact, degraded the band further by adding digital hash to adjacent channels, limiting the on channel analog bandwidth to less than 5 KHz and creating on channel background hiss.

Thus, HD Radio™ has done neither of those two stated goals.  In addition to that, from the radio station owner/operator’s perspective, it is expensive to install, expensive to license, expensive to operate and has no audience.

Hat from here.

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.


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