E4404B对齐问题

嗨，我最近买了一台E4404B频谱分析仪。
根据“ESA SA入门指南”，我开始运行内部对齐 - 我将AMPTD REF OUT连接到INPUT，并在一些预热时间后将其设置为“Align Now，All”。
它完成了没有错误的对齐，但当我将Amptd Ref输出为ON以查看信号时，它没有显示-20dBm @ 50 MHz，而是-28dBm。
我试图连接外部发生器（也是-20dBm @ 50 MHz），它仍然显示-28 dBm。
然后在查看控制选项时，我找到了一个更改耦合模式的选项。
当我将它设置为DC时，它实际上显示正确〜-20dBm，但当更改回AC - > -28dBm时。
然后我就这样离开了，过了一会儿我注意到它显示的是+10 dBm。
然后我再次尝试将其改为直流耦合，它显示+ 5dBm。
当改回AC耦合= -14 dBm时。
然后我将它设置为再次对齐，并且在完成后它在〜-10dBm和〜+ 10dBm之间跳跃，而AC耦合并且在DC耦合时不断地读取〜-19dBm（仍然具有相同的-20dBm 50MHz ref信号）。
我已经尝试多次运行对齐并再次得到不同的结果，例如，一次对准后，在AC耦合时显示-30 dBm，在DC耦合时显示+ 5dBm。
大约一分钟后它跳到-16dBm（AC）和-20dBm（DC）。
此外，当我尝试运行Align Now时，RF有时会发现没有找到参考信号，但有时会成功完成该过程（但我会得到不同的结果，例如3dBm（AC耦合）和-1dBm（DC耦合））。
我之前从未使用频谱分析仪，一般来说我对RF的东西很新，所以任何建议/想法都将受到赞赏。
在此先感谢Vents P.S.
在阅读了这个论坛上的一些主题后，似乎混音器可能会损坏。
我读到，在混合器损坏的情况下，本底噪声很高。
当我将频率范围设置为全范围时，实际上0-3GHz范围内的本底噪声为〜-30dBm，而在> 3GHz范围内为〜-55dB。
如果是这种情况，有人可以提供一些有关维修程序的信息吗？编辑：2013年12月2日上午3:29



     以下为原文

  Hi,

I recently got an E4404B spectrum analyzer. According to "ESA SA Getting Started Guide" I started with running internal alignments - I connected AMPTD REF OUT to INPUT and after some wARMup time set it to "Align Now, All".

It finished aligning with no errors, but when I turned Amptd Ref out ON to view the signal, it didn't show -20dBm @ 50 MHz, but -28dBm instead. I tried to connect external generator (also -20dBm @ 50 MHz) and it still showed -28 dBm. Then while looking through control options I found an option to change coupling mode. When I set it to DC,  it actually showed correctly ~ -20dBm, but when changed back to AC -> -28dBm. Then I left it like that and after a while I noticed it was showing +10 dBm instead. Then I tried again to change it to DC coupling and it showed +5dBm. When changed back to AC coupling = -14 dBm. Then I set it to align again and after it was done it was jumping between ~ -10dBm and ~+10dBm while AC coupled and reading constantly ~ -19dBm while DC coupled (still with the same -20dBm 50MHz ref signal).

I have tried to run aligned a few more times and got different results again, for example, one time after alignment it showed -30 dBm while AC coupled and +5dBm while DC coupled. After a minute or so it jumped to -16dBm (AC) and -20dBm (DC).  
Also, when I try to run Align Now, RF it sometimes says that no reference signal was found, but sometimes completes the procedure successfully (but again I get different results, e.g. 3dBm (AC coupling) and -1dBm (DC coupling)).

I have never before worked with a spectrum analyzer and generally I'm pretty new to RF stuff, so any suggestions/ideas will be appreciated.

Thanks in advance
Vents

P.S. After reading some threads on this forum it seems that a mixer could be damaged. I read that in the case of a damaged mixer the noise floor would be high. When I set the frequency span to full range, indeed the noise floor in 0 - 3GHz range is ~ -30dBm compared to ~ -55 in >3GHz range. If that is the case, could someone please provide some information about repair procedure?

Edited by: Vents on Dec 2, 2013 3:29 AM