history – Page 14 – Engineering Radio

Bell System microwave relay system

This is a map of the AT&T microwave relay system as it was in 1960. It is interesting for several reasons. First of all, before there were communications satellites, this is the way that data was transferred from one location to another. That data would have been digitized and TDM encoded on a T-carrier, then loaded onto a microwave path. TV networks had loops that transversed the country, distributing network video and audio to all the markets in the US. The first transcontinental New York to San Francisco microwave route was established in 1951. Through the fifties and sixties, the network was filled in across the US and Canada.

Radio networks had been using wired TELCO networks for program distribution for years, although they required far less bandwidth than TV. This was during the time when network affiliation was vitally important to a station. Radio networks provided news and other special event programming, as well as some long-form shows which were an important source of information for the listeners. Any network programming prior to 1980 or so would have been carried by this system.

It was not until the use of C and Ku band satellite services that networks could offer multiple channels of programming. Now, entire radio formats could be programmed remotely and beamed into hundreds of stations across the country simultaneously. That would have been far too expensive to implement over TELCO lines, as the line charges were based on the mileage of the circuit.

Click for higher resolution.

This system included thousands of hardened microwave relay sites, each built to exact specifications and fully redundant. At the time, the long-distance telephone system was an integral part of the US defense planning. Sites were spaced 20-40 miles apart, depending on terrain. In congested areas, like the northeast, area mountain tops are dotted with these sites today, mostly empty. Most of these sites went offline in the late 1990s as phone companies switched to fiber optic cables for telephone and data traffic.

American Tower, Inc. purchased most of these sites in bulk from AT&T in the year 2000. Some sites are well positioned for Cellular Telephone, 3G, and 4G wireless data services, plus other things like Media Flow and general use applications like FM broadcast and two-way. Many sites, however, do not meet any specific needs and sit empty. There was a large fire sale by American Tower in 2002 in which they unloaded about 1,900 of these sites as they were redundant.

I wrote a post titled Cold War Relic: ATT long lines site, Kingston,NY detailing one of these sites near me. Keep in mind, there were thousands of these sites throughout the country.

Milwaukee’s oldest radio station

WISN 1130 AM has been on the air since 1922, although not always with those call letters. In an interesting twist, the license was granted to the local newspaper, the Wisconsin News, and the Milwaukee School of Engineering. Initially, both entities were programming the station, however, by about 1925, the newspaper was responsible for programming and the engineering school was responsible for technical operations.

In 1941, the station increased power from 1,000 watts to 5,000 watts and added nighttime service. This is a series of pictures from that time period.

Back in 1941, nighttime interference was taken seriously. The nighttime allocation study (on 1150 KHz, WISN’s former frequency) includes co-channel stations in the US, Canada, Cuba, and Mexico.

The array consisted of four Blaw-Knox self-supporting towers in a rectangle. Notice the lack of fencing, warning signs, and the like around the towers.

From the front of the transmitter building

The site looks well designed, no doubt manned during operation, which at the time would likely be 6 am to midnight except under special circumstances. Most of these old transmitter sites had full kitchens, bathrooms, and occasionally a bunk room. The transmitter operators where required to have 1st telephone licenses from the FCC. There is only one manned transmitter site in the US that I know about; Mount Mansfield, VT. There, WCAX, WPTZ, WETK, and VPR have their transmitters.

The WISN RCA BT5E transmitter looks huge for that power level. Back in the day when AM was king, these units were designed to stay on the air, no matter what. I don’t know too much about this model transmitter, but if it is like other RCA/GE models from the same era, it has redundant everything.

Old school antenna monitor. I have never seen one of these in operation, however, as I understand it, the scope was used to compare the phase relationship of each tower against the reference tower.

These pictures are of the WISN 1150 array was it was in 1941. Since then, the station has changed frequencies to 1130 KHz and increased power to 50,000 watts daytime/10,000 watts night time. The daytime array consists of six towers and the night time array has nine towers, all of which are 90 degrees.

Special thanks to John A. for sending these pictures along.

The Tandy TRS-80 Model 4D computer

File under: You can find the darnest things at the transmitter site. Near as I can tell, this computer dates from about 1985 or so, it looks remarkably like my Apple IIe of the same vintage. We used an earlier model TRS-80 in high school, that model had a cassette deck as the data storage device. These have 5 1/4 inch floppy disks. I used my Apple IIe as a gloried type writer, mostly for college papers. I did manage to write some basic programs, no doubt copied from somewhere else.

For the day though, saving something for later editing, even to a floppy drive, was an order of magnitude over the single spaced type written page.

There are actually two of these computers, serial numbers 7086 and 7128. I have no idea whether they work. I’d donate them to a museum if there were one that was interested. Otherwise, they may sit in the corner for another twenty years or so.

WICC Station Operating Report

From February 8, 1940:

I found this in one of the file cabinets at the transmitter site. It was apparently used as scrap paper because there is what looks like connection information for a remote control system scrawled on the back. I thought it was interesting as it shows a 6 a.m. sign-on and the type of programming, source, and exact times each element ran. For Origins, YN = Yankee Network, BPT = Local Studio (Bridgeport), and NBC = NBC. Program logs for later years (1943) show the Alarm Clock Salute was received via FM from W43B (Paxon, MA) on 49.3 MHz.

Sign-off was at midnight. It must have been cold in that little house out on the island in February.

Anyway, I’ll save these in my radio station history files.