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Old June 1st 04, 01:12 PM
Odd Erling N. Eriksen
 
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Default Effect of substituting ferrites with ordinary resistors in PA circuit?

Hi,

I am currently trying to debug somebody else's UHF telemetry transmitter
design. My primary concern at present is that the PA module (RF Micro-
devices 2117) datasheet states that ferrites of certain values should
be put in series with the bias voltage, power down control voltage and
RF input.

On the PCB I am evaluating, the ferrites have been substituted with
ordinary thick film SMD resistors of the same ohmic values.

My question, then, is the following: In what way is it likely that this
affects the operation of the PA?

-Nonlinear operation because of noisy supply voltage?
-Excessive intermodulation due to stray RF being let into the chip?
-Anything else?

I am not very experienced in applied electronics, I am afraid - the MSc.
studies I am currently undertaking focus (way to much!) on the
theoretical approach. Sigh.

Thanks in advance for any qualified guesses!

--
73 de LB1LF

Odd Erling, ARK

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