HP 8753E manual Active Channel Keys, Auxiliary Channels and Two-Port Calibration

Active Channel Keys

The analyzer has four channels for making measurements. Channels 1 and 2 are the primary channels and channels 3 and 4 are the auxihary channels. The primary channels can have different stimulus values (see “Uncoupling Stimulus Values Between Primary Channels,” below) but the auxiliary channels always have the same stimulus values as their primary channels. That is, if channel 1 is set for a center frequency of 200 MHz and a span of 50 MHz, channel 3 will have the same stimulus values. This permanent stimulus coupling between primary and auxiliary channels is:

Channel 1 = channel 3 (by stimulus)

Channel 2 = channel 4 (by stimulus)

This stimulus coupling between a primary channel and its auxiliary is reciprocal; if you change a stimulus variable in an auxiliary channel, it immediately applies to its primary channel as well.

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Figure 6-3. Active Channel Keys

The @iFi) and [W) hardkeys shown in Figure 6-3 allow you to make a channel “active. n Once active, a channel can be configured independently of the other channels (except the stimulus values of an auxiliary channel, see above). The front panel hardkeys and softkeys are used to configure a channel while it is active. All of the channel-specific functions that you select apply to the active channel.

Primary channels 1 and 2 can be made active anytime by pressing @GET) or ($iK?J respectively. However, before you can activate auxihary channel 3 or 4 through these keys, you must do two things:

1.Perform or recall a full two-port calibration.

2.Enable the auxiliary channel through the (~isplad menu.

Note	The @iGTF ) and @LZT) keys retain .a historyFF of the last active channel	or
	example, if channel 2 has been enabled after channel 3, you can go back to
	channel 3 without pressing [chanj twice.

Auxiliary Channels and Two-Port Calibration

A full two-port calibration must be active before an auxiliary channel can be enabled. The calibration may be recalled from a previously saved instrument state or performed before enabling an auxiliary channel. If recalled, you may need to modify some of the parameters from the recalled instrument state in order to apply it to your particular device. The recalled calibration must cover the range of the device to be tested.

If a calibration is performed while one or both auxiliary channels are enabled, the auxiliaryy channels will be disabled, then enabled when the calibration is complete.

6-6 Application and Operation Concepts