[time-nuts] Thunderbolt distribution amplifier needed

Charles P. Steinmetz charles_steinmetz at lavabit.com
Wed Aug 22 06:43:31 UTC 2012


>Remember  *  *  *  these DAs are designed be unity gain and to 
>handle approximately 1 volt p-p so be carefull of clipping if you 
>drive much more than that level or alternatively, pad down the input 
>to a 1 volt level.

Also, video DAs are designed to drive 75 ohms (the video world's 
standard distribution impedance), so you will get additional 
attenuation at the output if you are driving 50 ohms, and you may get 
current clipping.  That said, some video DAs work quite well at 10 
MHz/50 ohms/+13 dBm (= 1 V rms = 2.8 V p-p) if you modify the 
internal input and output impedances.  In some cases, you can reduce 
the added phase noise by reducing the LF gain.

Best regards,

Charles









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