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RE: Isolation transformer and 9600 baud.


By wild coincidence, I swept the response of a few audio transformers last
week.  One caveat is that I used a 10K termination, because that is what my
FT-847 shows.  I tested some others, but was pleasantly surprised by the RS
1:1 isolation transformers.  Even though they are only rated to 5 KHz, they
are flat from about 30 Hz up past 30 KHz, with the upper 3 db compression
point around 43 KHz.  Common mode rejection is also good.  Surprised the
heck out of me.  As stated, they have an input impedance of around 800 ohms,
which possibly might load down some configurations.  I tested some coupling
transformers with 10K impedance, from All Electronics, and about the only
difference was the better matching, and totally irrelevant lower frequency
response.  I too had heard many comments about using direct coupling for
higher baud rates, and got to wondering.  I am still wondering!  


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