[time-nuts] Hp 58503A

Charles P. Steinmetz charles_steinmetz at lavabit.com
Tue Oct 16 14:41:51 EDT 2012


>I  just loaded it down with a 50 ohm load and looks perfect.

One of my design pet peeves is not anticipating what users may 
do.  For example, not anticipating that someone might terminate an 
output in a high impedance rather than in the rated impedance, or 
leave unused outputs unterminated.  I have seen several multichannel 
isolation amplifiers where any output not terminated in 50 ohms is in 
hard clipping -- even with halfway decent isolation, this can put 
garbage on the other outputs.  The very definition of an isolation 
amplifier is that each output should be independent of how the other 
outputs are terminated -- short, open, inductor, capacitor, other 
signal, whatever.  I understand it is not trivial to provide 1 Vrms 
(+13 dBm) outputs with 6 dB overhead from a 5 V (or 3.3 V) supply, 
but that's why they pay designers the big bucks.


Best regards,

Charles








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