There are two marker position controls (hereafter called simply “marker controls”), Marker 1 and Marker 2, which are R43 and R44 respectively. The Marker controls are identical in function. Since they utilize the same marker circuit, only one can be used at a time.
The M1 and M2 buttons determine which of the marker controls is active. Pressing M1 enables the Marker 1 control and disables the Marker 2 control. Pressing M2 enables the Marker 2 control and disables the Marker 1 control.
The marker controls serve two functions. One function is to control the frequency of the oscillator when in “Marker Mode” and the other function is to attenuate the Waveform Output when the generator is producing the frequency to which the currently active marker (Marker 1 or Marker 2) is set.
Several of the controls on the instrument can affect the Waveform frequency. Pressing the “Marker Mode” button makes the currently active marker control (Marker 1 or Marker 2) control the Waveform frequency. Other Waveform frequency controls are selected by pressing Low Freq, Sweep, or High Freq.
To set a marker frequency, press Marker Mode and select Marker 1 or Marker 2. Adjust the Waveform frequency by selecting the band and adjusting the actiove marker control (Marker 1 or Marker 2). When the Marker On/OFF button is pressed, the marker attenuation of the Waveform frequency is toggled. When the Waveform frequency is being swept, the marker will put a notch in the output waveform
This makes it easy to identify a particular frequency in the sweep. There are two marker controls which allows a little flexibility in that one can mark two different frequencies.
The Marker Output of the sweep generator can also be used to indicate a frequency’s position within a sweep. The Marker output is shown as the blue waveform in the photograph above.
The Marker can also be used to identify the frequency of an interesting feature, such as a peak in response. In the photograph below, the Marker is set at the peak response of a ceramic filter being swept.
In this case, the Marker control was adjusted so that the Marker Output was aligned in time with the peak in the filter’s response. After setting the position of the marker, the Marker Mode button was pressed, which stopped the sweep and the Waveform frequency is set to the Waveform frequency that corresponded to the center off the marker pulse (the blue pulse in the photograph above). The Waveform frequency was then measured to determine the marker frequency.
Contents ©2008 Richard Cappels All Rights Reserved. Find updates at www.projects.cappels.org
LCD library copyright by Peter Fleury http://homepage.hispeed.ch/peterfleury/ and may only be used for noncommercial purposes and is provided here with his permission.
First posted in January, 2008 You can send email to me at projects(at)cappels.org. Replace "(at)" with "@" before mailing.
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