Removing the bypass capacitor will also improve the linearity of the
amplifier. The attenuator will not.
73
Bill wa4lav
At 07:34 AM 7/23/2003 -0500, you wrote:
>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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