IC24AT.1

Subject: Re: IC-24AT Receive Mods

Following the frequency expansion modification (as specified by Icom), a
sample IC-24 was recently tested for tuning range and input sensitivity
for an S9 signal.  While the sensitivity measurements should not be directly
compared with the manufacturer's specifications (usually measured reference
to a signal-to-noise quieting ratio), this "quick and dirty" data should
give you a good idea of the sensitivity to a medium-strength signal.

  Tuning Range         Mode     Band       Sensitivity for S9 Signal

       74 - 107.995 MHz (fm)  VHF range         approx 1 mV
      108 - 136     MHz (am)  VHF range         10 - 30 uV
      138 - 240     MHz (fm)  VHF range         1 uV - 1 mV (1)
      250 - 302     MHz (am)  VHF range         50 uV - 1 mV (2)
      310 - 354.995 MHz (fm)  VHF range         50 uV - 3 uV (2)

      355 - 409     MHz (fm)  UHF range         3 - 10 uV
      417 - 490     MHz (fm)  UHF range         1 uV - 100 uV (3)
      805 - 955     MHz (fm)  UHF range         10 - 100 uV

      Notes:

      (1) The sensitivity from 138 - 150 MHz was 1 uV.  From 150 - 240,
  the sensitivity decreased almost linearly from 1 uV to 1 mV
  (with input voltage plotted logarithmically).

      (2) The sensitivity increased almost linearly for both these ranges
  (with input voltage plotted logarithmically).

      (3) The sensitivity plot looked like a "U" with the bottom of the
  "U" corresponding to the range 440 - 450 MHz (1 uV).  The
  sensitivity then got worse below 440 and above 450.

(Tests courtesy of WB6GTM)


%
proceed at your own risk.  WA2ISE
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continued in file ic24at.2