IMDx源功率校准问题

我正在使用带有两个内部源和组合器的N5241A PNA-X进行IMDx测量;
端口1是输入，端口2是输出。
我在DUT输出端测量相对于载波的IM3，在音调功率对话框中输出音调功率设置为-5dBm;
我还将功率调平设置为“设置输出功率，接收器调平”并选中“耦合音功率”和“ALC开启”。
当我在通道1上执行源校准时，我一直将功率电平设置为大约-35dBm，因为DUT具有大约40dB的增益。
内部源扫描感兴趣的频率范围-35dBm，没有错误。
然后，根据测量窗口开始第二次扫描，其为-5dBm。
此时校准失败（35-40dB），并在屏幕上弹出几个“Src1 Unlevel”和“Src2 Unlevel”错误消息。
如上所述，我将两个信号源的输出功率配置为由音调功率对话框中端口2上产生的-5dBm信号控制;
为什么分析仪会尝试在端口1上测量此功率？
我假设显着的校准失败是由于端口2上没有任何信号，因此没有电源到达B接收器;
为什么校准向导没有提示我将电缆从端口1连接到端口2？
另外，如果有一种方法可以使用校准向导使用-5dBm信号校准B接收器，我可以使用这两个内部信号源吗？
很明显，这两个光源不能产生-5dBm的两个音调。
帮帮我！
-担



     以下为原文

  I am performing a IMDx measurement using a N5241A PNA-X with two internal sources and combiner; port 1 is the input and port 2 is the output.  I'm measuring IM3 relative to carrier at the output of the DUT with the output tone powers set to -5dBm in the tone power dialog box; I've also set power leveling to "Set Output Power, Receiver Leveling" and checked "Coupled Tone Powers" and "ALC On".

When I'm performing the source calibration on channel 1, I've been setting the power level to approximately -35dBm since the DUT has approximately 40dB of gain.  The internal sources sweep across the frequency range of interest at -35dBm with no errors.  Then, a second sweep begins that according to the measurement window is at -5dBm.  The calibration fails significantly at this point (by 35-40dB) and several "Src1 Unlevel" and "Src2 Unlevel" error messages pop up on the screen.

I configured the two sources' output power to be controlled by the resulting -5dBm signal present on port 2 in the tone power dialog box as I described above; why does the analyzer try to measure this power on Port 1?

I'm assuming the significant calibration failure is due to there not being any signal on Port 2 and so there is no power getting to the B receiver; why didn't the calibration wizard prompt me to connect a cable from Port 1 to Port 2?  Plus, if there is a way to calibrate the B receiver with a -5dBm signal using the calibration wizard, can I use the two internal sources?  It's apparent that the two sources are not capable of producing two tones at -5dBm.

Help!
-Dan