Downgrading an AM radio station

WGHQ in Kingston, NY has been downgraded from a 5KW DA-1 to a 1KW non-DA system.  This was done because two of the three towers in the directional antenna array dated from 1960, were in very rough condition and needed to be replaced.  The remaining tower (furthest from the transmitter building) had been replaced in 1994, is in good condition, and is being kept as the non-directional radiator.

Here are a few pictures:

WGHQ 3 tower directional antenna array, Port Ewen, NY
WGHQ 3 tower directional antenna array, Port Ewen, NY
More deferred maintenance
More deferred maintenance
RF and tower light feed disconnected from tower base
RF and tower light feed disconnected from tower base
Second tower base vegetation not as bad, tower disconnected
Second tower base vegetation not as bad, tower disconnected
WGHQ transmitter and original Collins phasing cabinet
WGHQ transmitter and original Collins phasing cabinet

First tower video (sorry, I appear to have no idea what I am doing with the camera):

Second tower video, this one is better:

Towers on the ground:

I made measurements on the third tower and constructed a temporary ATU with parts on hand to get the station back on the air. They are now running 1 KW day, 38 watts night, as per their CP. I will be going back up to finish the job once the brush has been removed from around the existing tower and the ATU building has been repaired.  The coverage with 1 KW is not bad, actually:

Predicted coverage map from FCC website
Predicted coverage map from FCC website

The translator is on the way.

Hitchhiker’s guide

Anyone that grew up a geek in the late 70s to early 80s (ahem) will get the references in this video:

For those of you that are unfamiliar:

The Hitchhiker’s Guide to the Galaxy is a comedy science fiction series created by Douglas Adams. Originally a radio comedy broadcast on BBC Radio 4 in 1978, it was later adapted to other formats, including stage shows, novels, comic book adaptations, a 1981 TV series, a 1984 computer game, and 2005 feature film.

I was most familiar with the video game, which came out about the same time I bought my first computer, the beloved Apple IIc. That might have been in 1986 or so.

Anyway… It is nice to see a new generation of enthusiasts among the current Engineering students.

So long, and thanks for all the fish.

The Ubiquiti Nano-Beam

I installed one of these wireless links between two transmitter buildings recently.  The Ubiquiti gear is not my first choice, however, the client insisted that we use this equipment likely because of its inexpensive nature (less than $65.00 per unit).  My overall impression is so-so.  They are fairly easy to set up; the AirOS is intuitive and easy to navigate around.  I had to upgrade the firmware, change the default user name and password, assign IP addresses, subnet mask, gateway information, SSIDs, security parameters, etc.  All of that was very easy to figure out.  My grip is this; it seems the hardware is a bit plastic-y (e.g. cheap).  I know some of the Ubiquiti models are better than others.  I hear good things about the airFiber units but they still don’t compare to the Cambium/Canopy gear.

For this installation, I used the shielded Ubiquiti “Tough Cable” with the shielded Ubiquiti RJ-45 connectors and Ubiquiti Ethernet Surge Protectors.  When making the Ethernet cables up, I made sure the shield drain wire was connected to the metal body on the RJ-45 connector.  I tested everything with my trusty Fluke Microscanner cable verifier which also shows continuity for the shield.  I am still not completely confident that the outdoor units will survive a lightning strike on the 898-foot (273.7 meter) guyed tower nearby.  Time will tell.

The system has a wireless path length of about 200 meters plus another 60 meters or so of Ethernet cable.  Latency when pinging the gateway across the entire network is about 3 to 4 ms (laptop>switch>nanobeam<->nanobeam>switch>gateway).  The network is being used for remote control/monitoring of transmitters and backup audio via Comrex Bric link II IP CODECs.

screen shot; Nano Beam Air OS
screenshot; Nano Beam Air OS v7.2.2

On the plus side, the 802.11ac link is very fast; 650+ Mbps unwashed link speed is pretty impressive.  Strip off the wireless LAN headers and that likely translates to greater than 500 Mbps goodput.  Also, the inexpensive nature of these units means that we can keep a few spares on hand in case something does suffer catastrophic damage due to a storm.  The AirOS v.7 is pretty cool with the RF constellation and other useful tools like airView (spectrum analyzer with waterfall display), discover, ping, site survey, speed test, traceroute, and cable test.

After installing the updated firmware, which fixes a major security flaw with the web interface, the link was established with three mouse clicks.  After that, I ran speed tests back and forth for several minutes.  Basically, the speed on the LAN is reduced because of the 100 Mbps switch.  Even so, that should be more than enough to handle the traffic on this segment of the network.