Tag: AM

I have been spending my days in Brookfield, Connecticut, dragging transmitters around and reconnecting them in various ways.  The WRKI-FM WINE-AM transmitter site is finally moving into the “new” transmitter building at the base of the tower.  Today, we moved WINE.

WINE was first signed on in 1963 on 940 KHz from a 170-degree non-directional tower on top of a pretty high hill.  That same tower serves as the antenna support for WRKI, which signed on in 1957.  The station runs 680 watts daytime, however since it is non-directional, it has some pretty serious power reductions at night.  The post-sunset power drops in two steps, 450 watts for the first hour, then 189 watts for the second hour, followed by 4 watts nighttime.

The 4-watt nighttime signal goes about 2-4 miles before it becomes unlistenable.  The Post Sun Set Authority (PSSA) allows the station to stay on the air with at least some coverage up to about 6:46 pm in the winter time and 10 pm in the summer, which is better than nothing.

The problem is, the Harris MW-1A transmitter goes down to 250 watts and no lower.  In order to make the nighttime power, the station switches to a dissipation network to burn off 246 watts of RF, at 50% percent AC-RF efficiency, which just ends up being a waste of power.  Further, the station engineers have been ignoring the PSSA because there are too many steps and it was easier to just switch to night power at sunset.

What we decided to do instead, was install a small low power night time transmitter, a Radio Systems TR-6000.  The MW1A can then be set to use the low power level for the first step of the PSSA, then switch the dissipation network in for the second step of the PSSA, and finally switch in the night transmitter at the proper time.

This is the Harris transmitter, new Circa 1981, which was cleaned up and moved into the new transmitter building.

The dissipation network.  This will have to be reconfigured for the proper power levels, once the night transmitter is installed.  The dissipation network is on the right, a dummy load is on the left.  The two large RF contactors switch the dissipation network in and out, or select which transmitter is feeding the antenna/dummy load.  This is the really, really old school way of doing it.  Most transmitters manufactured after 1990 or so can run at any power level, making a dissipation network unnecessary.

Before re-installing the dissipation network/dummy load, we lined the enclosure with copper mesh.  I don’t want that thing interfering with any of the other equipment nearby, which would be the STL receivers, satellite receivers, or Town of Brookfield police dispatch radios.

Schematically, it looks like this:

This is the picture behind the transmitters, which shows the coaxial cable feed through ports and the dissipation network on the wall.

It is a work in progress, so forgive the mess.

Still in use as the main transmitter after 42 years at WCKL 560 KHz, Catskill, NY.

The last seven years or so, it has not had much use, the station being caught in some strange LMA with Clear Channel, then sold to the Black United Fund of NY something or another. They basically had it dark, turning it on for a few days each year to as not to lose their license.  Finally, they LMA’d it to Family Broadcasting (not to be confused with Family Radio).  There are rumors of a sale, but it remains to be seen.

They have been broadcasting an eclectic, free-form programming style which appears to be the work of mostly volunteers.

The station was first licensed in 1970, thus this is the original transmitter:

Towers are 446 feet tall, which works out to 90 degrees at 560 KHz.

The station is licensed to Catskill, but the transmitter site is located in Hudson, across the river. With the current ownership situation in flux, I would characterize the operation as “tenuous.”

The transmitter itself is a pretty simple high level modulation tube type transmitter.  It uses 4-400 tubes, like the RCA-BT1AR transmitters, and is built around a similar design, which makes sense as they were designed and built by former RCA engineers.  One of the CCA principles, Bernie Wise, still makes Energy Onix transmitters about 10 miles away in Valatie, NY.

Parts are fairly generic and still available.  Things like the modulation transformer may be harder to come by, however, Goodrich Electronics, Harbach Electronics, Energy Onix and others will be able to steer one in the right direction. I’d put up a schematic if I could find one.

I find these older tube-type transmitters often sing with modulation, especially the higher frequencies.  That sound and the soft sound of the blower moving air is the sound of radio, at least to me.