Studio renovation, WBLI

A quick humorous video shot by the staff of WBLI, Patchogue, (Long Island) NY. I was personally not involved with this. The old console looks like a PRE (or Harris) Airwave. I did not see the new console.

h/t Skywalker

Do radio transmitters have the capability of electrocuting copper thieves?

I found that question while perusing my search engine statistics today.  The short answer in theory is yes.  If you are a copper thief, it will most likely look like this:

That being the case, however, it is much more likely that an RF burn will result if one comes in contact with an energized antenna or transmission line.  Even small RF burns are painful, large ones can be nasty things.  RF burns occur because of the skin effect, that is to say, the higher the frequency of the AC waveform, the closer to the surface of any given conductor the current will flow.  It is the reason why five watt STL transmitters on 950 MHz use 7/8 or 1 5/8 inch cable to reduce losses.

When a human body part comes in contact with an energized RF antenna, the body part becomes part of the circuit, thus it follows the same principals.  The extremity that is making contact will have its skin burned off.  It also smells bad.

Getting an RF burn is a painful lesson on what not to come in contact with around a transmitter site.  But, that is not all.  Simply being in close proximity to radiating elements of antennas will induce body tissue heating, just like a microwave oven.  This can lead to all sorts of short term and long term damage to organs and other problems.

Therefore, the best thing is to avoid radio and cellular towers if you do not know what you are doing.   Stay out of fenced in areas around tower bases.  No matter how tempting that copper may look, you could be seriously injured or killed if you cut the wrong thing.

The Telos NX-12 Talkshow phone system

I have worked with my Telos telephone interfaces in various studios. They are well designed and intuitively designed pieces of equipment. The Telos NX-12 is no different.  The first thing different about this telephone system is the web interface.  I have commented before on this; eventually all broadcast equipment will have some type of http interface.  For configuration and monitoring, it makes life much simpler.

Telos’ NX-12 web interface allows the users to define phone lines, call directors and studios:

Telos NX-12 http interface
Telos NX-12 http interface

The NX-12 itself is just a box residing in the rack room.  This is where all of the pots lines or the PRI-ISDN line is installed, firewire, network interface, etc.

The studio end is the call director, which is connected to the NX-12 by a cat 5 cable.  There can be up to four call directors per NX-12.

The nice thing about the NX-12 is that the hybrid can be split into completely separate units, thus one NX-12 can be used for two separate stations, each with up to six lines.  Splitting the hybrid thus requires the use of Firewire or the unit must have an AES card.

This particular unit was installed at WFAS-AM/FM in White Plains, NY.

The General Electric XT-1-A AM transmitter

I found this photograph in a filing cabinet the other day as a part of a sales proposal dated 1948. I have never seen one of these in the field. They look like very sturdy units:

General Electric XT-1-A Standard Broadcast transmitter
General Electric XT-1-A Standard Broadcast transmitter

Back in the day when AM was king, no expense was spared on transmitting equipment.  I remember the GE BTA-25 transmitter from the same era, it was build like a tank.  Once, while we were repairing the Harris MW-50A main transmitter, the old GE burped, sputtered and threw an IPA overload, then returned to air.  I looked in the IPA cabinet and found a mica capacitor had been blown in half.  It was in the tuning circuit, but apparently there was still enough capacitance in the circuit for the transmitter to keep running.

This unit looks similar to that one.  The simplified schematic:

General Electric XT-1-A schematic diagram
General Electric XT-1-A schematic diagram

Like other 1 KW AM transmitter designs, this unit uses the venerable 833A triode.  There are some advantages of this tube, as extra circuits for PA stage neutralization are not needed.  The full sales brochure can be found here (medium sized .pdf).  These were manufactured in Syracuse, NY.

The asking price in 1948 was $8.730.00, tax and shipping extra.