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Do you remember?

The Tektronix Type 561A oscilloscope was used to check performance characteristics of FM stereo generators and 10W FM transmitters. Seventeen amplifier and time-based plug-in units could be used for different types of applications. The unit displayed single or multi-trace presentations. The upper trace displayed a composite left only signal, including the 19kHz pilot carrier. The lower trace presented the 38kHz L-R subcarrier. The oscilloscope provided an 8cm × 10cm viewing area. In 1964, this piece of equipment's retail price was $500, not including plug-in units.

That was then

The motor generator room of the General Electric station KGO in Oakland, CA, contained nine motor-generator sets. In 1924, these supplied current for heating the filaments of the tubes, plate potential for the power amplifiers, bias potential for the amplifier and modulator tubes, and excitation for the various generators. These machines were all in duplicate, thus ensuring a continuous program in the event of failure. Motor generators were required to create the dc power because high-voltage rectifiers were not yet available.

Source: John Schneider's Broadcast History at

Sample and Hold

Radio by the numbers


The average number of years respondents have worked in the broadcast engineering field.


The average number of individual stations (AM or FM) radio engineers are responsible for.


Percentage of station chief engineers that say computer/IS/IT functions are considered the engineering department’s responsibility.


Percentage of radio stations that plan to implement or already have commenced IBOC transmission.

Source: 2004 Radio magazine Salary Survey.

Question of the Month

The digital transition
The first digital device at many radio stations was a CD player. Since then computer-based audio storage and playback systems, DAWs, audio processors and consoles have made the switch. It is possible to have a completely digital air chain from the output of the mic preamp to the input of the exciter and possibly the antenna.

Please take a moment to complete our survey. The results will be published in the March 2005 issue.

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