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Albert |
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 噪声二极管的使用方法（NW301） |
 2006-11-27 14:03:10 |
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the pot can be used 200 ohms fixed resistor, but I calculate the current I = 12/200=60mA when the diode is penetrated through. It means the current will higher than 8 mA. When I test my circuit, I adjust the pot between 1k ohms to 3k ohms. I find the diode A point has only 2.8V(highest). It is burned out when I try to adjust the pot decreasing to promote the voltage. I want to know how to control the current when the voltage is 12 v.
Maybe I should put the diode to power and let the pot to GND.
By the way, I hope the diode can work the GHz region. |
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 2006-12-6 20:55:16 |
You want to do exactly what you are doing but add a series resistor after the pot.
This will prevent the pot from being adjusted to 0 ohms or a low value which will blow up the diode without another resistor.
The diode breakdown voltage is ~ 10.5 V. So if you bias it up correctly then the maximum diode current will be I=(12-10.5)/200=7.5 mA. This would be the maximum current that you can set. What probably has happened is that without this resistor you can inadvertently set the current very high and blow up the diode. When they blow they will be around 3 V.
Replace the diode that is in there ( make sure the marked side is facing the pot and the unmarked side is grounded) and add a 200 Ohm surface mount chip resistor. I would put this between the pot and the junction that connects the cathode of the diode and C1 the coupling cap.Then you will be able to safely vary the pot and the current from 0 to ~7.5 mA. |
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射频微波 |
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| 温度补偿衰减器的特性 |
2006-11-27 13:56:43 |
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我希望知道贵司所代理的温补衰减器在不同频率范围下以及不同温度条件下它的补偿特性是否有何变化。 |
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2006-12-6 20:34:23 |
我们的温度补偿衰减器，它是随温度的变化，它的衰减量随之而变化的，它有固定的一个“温度—衰减量”曲线。
当然，频率对补偿（衰减量）也有一些影响，但是影响不大。随频率的升高，主要是VSWR会差一些。
您如果对产品感兴趣的话，可以到我们资料下载页面，PDF的资料里有不同的温度补偿曲线的资料的。
关于和频率的关系，你也可以问我们要S参数的文件。谢谢！ |
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