电缆测试失败

如果您给出一些测试结果的指示而不是“失败”，那么它会有所帮助。发布一个情节，甚至是一个中频数字。
所有VNA都在测试端口后面有50欧姆端子，即使原理图上没有显示。
如果通过断开前面的“循环”重新配置测试系统，而不是正确地重新组合，则可能是测试端口未终止的情况，但这可能是不寻常的。
您的设置很好，除了IF BW，精度测量应为1kHz。
不是35 kHz不能提供精确测量，而是在1 kHz时我们自动切换到步进扫描模式。
电缆测试需要逐步扫描更长的电缆（事实上，如果差异很小，则您的电缆很短）。
但是你没有提到你的校准。
如果不使用“智能卡”选项，则很容易进行错误的校准，但使用较旧的“无引导校准”，特别是在每个端口上具有相同连接器的电缆上。
用户通常会在非制导卡中放置一个短的公对公适配器，但它不是校准套件的一部分。
Smart cal修复了这个问题。
事实上，我有两个关于引导（智能）cal和非引导cal的简单规则：你何时使用Guided（Smartcal）？
总是你什么时候我们没有指导cal？
决不。
发布您的数据，以及您如何进行校准，我们将为您解决问题。



     以下为原文

  It would help if you gave some indication of the test results rather than "it failed"   Post a plot, or even a mid-band number.

All VNA's have 50 ohm termininations behind the test port, even if it is not shown on the schematic.  If the test system were re-configured by disconnecting the "loops" on the front, and not put back together correctly, then it might be a case where the test port was not terminated, but that would be unusual.

Your setup is fine except for the IF BW which should be at 1kHz for precision measurements.  Not that 35 kHz can't give precision measurements but rather at 1 kHz we automatically switch to step-sweep mode.  Cable testing requires step sweep for longer cables (in fact, yours are short should the difference should be small).

But you don't mention your calibration. It is very easy to make a bad calibration if you don't use the "smart-cal" choice, but use the older "unguided calibration" especially on cables that have the same connector on each port.  Users often place a short Male-to-Male adapter for the thru in unguided cal, though it is not part of the calibration kit.  Smart cal fixes that.

In fact, I have two simple rules about guided (smart) cal and unguided cal:  

When do you use Guided (Smartcal)?  Always
When do you us unguided cal? Never.

Post your data, and how you did the cal, and we will sort you out.

谢谢Joel博士以下是给我的测试结果。
谢谢你的帮助。
克里斯



     以下为原文

  Thanks Dr Joel

Here are the test results as they were given to me.  Thanks for your help.

Chris

附件

• Navy Test Plots.pdf390.0 KB
  

嗨Dr_joel，你有没有机会看看我发布的测试结果的屏幕截图？
谢谢，克里斯



     以下为原文

  Hi Dr_joel,

Have you had a chance to look at those screen shots of the test results I posted??

Thanks, Chris

这些情节告诉我你的电缆在两个端口都有不良匹配。
这可能来自不良的校准套件，坏的电缆连接器或组合。
2：1的SWR意味着失配损耗大约为0.51 dB。
相同频率下的损耗为.75，这意味着一些是来自不匹配，一些来自有损电缆。
此外，如果存在系统问题，它将有助于获得更多积分。
最后，对于电缆测试，我会将IF BW设置为1 kHz以获得最佳精度（但在这种情况下，我认为这不重要）。



     以下为原文

  The plots tell me you have a cable that has bad match on both ports.  This could be from a bad cal kit, bad cable connector, or combination. The SWR of 2:1 means the mismatch loss is on the order of 0.51 dB.   The loss at the same freq is .75 which means some is from mismatch and some from lossy cable.

also, it would have helped to have many more points, to sort out if there is a system issue.  Finally, for cable test, I would have set the IF BW to 1 kHz for best accuracy (but in this case I don't think it would matter).

谢谢Dr_Joel，感谢您抽出宝贵时间解决这个问题。
这些电缆只有6英寸长，每端有一个邮件SMA连接器。
测试每根电缆的插入损耗为2 GHz至18 GHz CW，损耗小于0.02 dBm。
电缆也通过了开槽线VSWR测试。
我认为，如果这种电缆很糟糕，它将永远不会通过插入测试。
有什么想法？



     以下为原文

  Thanks Dr_Joel,

Thanks for your time on this problem.  These cables are only 6 inches long with a mail SMA connector on each end.  Each cable was tested for insertion loss from 2 GHz to 18 GHz CW with less then .02 dBm loss.  The cable also pass a slotted line VSWR test as well.   I would think that if this cable was this bad it would never pass the insertion test.  

Any thoughts on that??

这指向不良的calkit或不正确的校准技术。
如果测试实验室使用旧的“非引导校准”，那么如果在通过校准状态期间使用M-M适配器，则这种错误是常见的。
要使用m-m adpater，您还必须修改校准套件并添加适配器的延迟和丢失。
通常这没有完成，但是没有引导的cal（如旧版8510）不能再次保护错误。
这是一个常见的错误，也是我们添加引导校准（Smart cal）的原因，它使用Unknown Thru技术消除了这种错误。



     以下为原文

  This points to either a bad calkit, or improper calibration techniques.  If the test lab used the old "Unguided Calibration" then this kind of error is common if a M-M adapter is used during thru calibraiton state.  To use the m-m adpater, you have to also modify the calibration kit and add the delay and loss of the adapter.  Often this is not done, but unguided cal (like in the old 8510) doesn't protect agains the error. This is a common mistake and the reason we added Guided Calibration (Smart cal) which eliminates this kind of error bu using the Unknown Thru technique.