[time-nuts] Modified Extron DA [WAS: Rb video]

Charles Steinmetz csteinmetz at yandex.com
Fri Aug 9 16:44:05 EDT 2013


Bob wrote:

>The original design with 3x75 ohm outputs would be driving a 50 ohm 
>load rather than a 33 1/3 ohm load. That would put it "in spec" for 
>the CLC409 as opposed to just out of spec current limit wise.

Right.  Analog video generally ranges from 0 to +1 V, so as a 
DC-coupled video amp the peak current into 3x75 ohm loads would be 
+40/-0 mA.  Very comfortably within the capability of a CLC409.

A friend recently brought me another commercial video DA, which I'm 
helping him modify for use as a 1/5/10 MHz DA.  It uses EL2099 video 
drivers, which are specified to provide 440 mA (typical -- 360 mA 
minimum) of output current.  This part should be able to drive 12 or 
more parallel back-terminated 50 ohm loads to +13 dBm, if 
desired.  (Like the CLC409, the EL2099 is obsolete/NLA.)

Best regards,

Charles





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