Micro Radio goes to Occupy Wall Street

I read a very interesting article from John Anderson regarding the Occupy Wall Street movement’s 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 the use of amplified speakers and or public address systems. By using a micro radio station, persons in a crowd too far away to hear the 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 thought 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

Link to: HD RADIO™ GOES THE WAY OF THE LASERDISC PLAYER.

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 difference 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 spiral 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 jacket 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 are connected to the inner conductor slug and snugged down with a standard screwdriver
  • 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 its 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 transmitters for a combined output of 10 KW and got about 50 watts return, which was much the same as it was before.