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I would like to build a two way telemetry radio with very fast turnarround
times.

Can anyone reccomend a TX/RX antenna switch that is good for 1W, relativly
quiet and
can swith from TX to RX in ~ 2msec?


Paul (Kl7JG)

There are 2 approaches ... build a PIN diode switch (using PIN diodes
rated for the frequency and power levels involved and biasing them properly
to avoid unwanted non-linearities) or you could look into some of the GaAs
MIMIC switches made by NEC ... some of them can handle the power,
they typically switch in about 20 nsec, and they have the advantage of
requiring essentially no drive current (can be driven directly from 3-5V
CMOS outputs).

For data sheets, check California Eastern Labs' website at:

http://www.cel.com/prod/prod_rfics.asp

Scroll down to the GaAs section.

Look for a part with the highest 1 dB compression point available.
(for example a part with a 1 dB compression point of 33 dBm (2W)
would be more likely to generate undesirable distortion than a part
with a higher 1 dB compression point)

(CEL is the exclusive distributor in the US for NEC's parts)

Carl - wk3c