Good morning.
George, thanks for your comments about removing the source bypass resistor (I
should have said CAPACITOR)
from the 1st IF JFET amp in my RX-320 to cut down the front end gain.
A resistive attenuator in the antenna input will do about the same. Anything
that lowers the front end gain or input signal level will boost the IMDDR3
by the same amount.
73/72, George
Amateur Radio W5YR - the Yellow Rose of Texas
I have used the attenuator approach, but it reduces the noise figure or minimum
discernable signal
of the receiver. The big advantage of reducing the gain with the approach that
I mentioned is that while the
dynamic range and 3rd order intercept are improved, the noise figure is not
degraded much. While the
use of the front end attenuator will increase the 3rd order intercept, it
degrades the noise figure by the amount
of attenuation and does not improve the dynamic range.
Regards,
Jack, KE4ID
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