[hpsdr] LTC2208 input, a warning

[rihob., es7aaz]

A very good reading about RF grounding.

http://www.radioworks.com/nbgnd.html

73,
Riho, ES7AAZ


rihob., es7aaz wrote:
> ***** High Performance Software Defined Radio Discussion List *****
> 
> Last but not least:
> 
> Never forget proper grounding when several devices
> are connected together !
> 
> 
> 73's
> Riho, ES7AAZ.
> 
> 
> 
> lstoskopf at cox.net wrote:
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> I'm cross posting this to this list and QS1R list although not an 
>> issue on Mercury unless you mess around in it.
>>
>> I'm a very happy user of the QS1R and the GUI is out of this world.  I 
>> wanted to use it as a 2nd receiver for the Orion.  Luckily TT put an 
>> RF out just after the RX input filters and I simply plugged a cable 
>> there, into one of the Z10000 buffer amps (google that) using a AD8007 
>> as a Hi-Z buffer with 9 volt to the amp, gain 6 and a pad after, and 
>> the output to the spare connector on the back of the rig.  What could 
>> possibly go wrong.  Worked great and the AD8007 provided a safety 
>> buffer.  Or should I say, worked great for a while.
>>
>> One day the SW came up "Buffer overflow" and the clipping light came 
>> on.  After trying several different computers with the same result, 
>> Phil C. asked me to send it back as I had blown the LTC2208.  It is on 
>> the way back fixed.
>>
>> I had forgotten that the max input is Vdd +0.3 volts, not the maximum 
>> voltage swing with power applied!  Since I picked the supply voltage 
>> for the buffer from the Orion, the buffer could easily exceed 0.3 
>> volts and if the QS1R wasn't turned on yet and invitation to blow.  
>> Clipping diodes won't help there.  You need something tied to the QS1R 
>> supply.  Phil's input board will take care of that, but in the interim 
>> take care.
>>
>> N0UU
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