Modifications for the Icom IC-775

Picture(s) of Icom - IC-775

19-07-1998 New product information IC-775DSP English language (5 Kbytes)
15-12-1999 IC-775DSP Out of Band Information English language (0 Kbytes)
19-11-2000 Increase the sensitivity on MW-band 0.5-1.6MHz on IC-775 and IC-775DSP English language
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19-11-2000
Increase the sensitivity on MW-band 0.5-1.6MHz on IC-775 and IC-775DSP
Author: SM4RNA Anders - sm4rna@telia.com


At the input at the bandpassfilter on RF-Unit for MW, 0.5 to 1.6MHz, a 10dB attenuator is located. This attenuator also is a current limiter for the diode D19.

By removing the attenuators three resistors and lead the diode current thru a inductor instead, the increased sensitivity is achieved. But important is to limit the current by changing the value on R119.

To do the mod:

  1. R116 is exchanged with an inductor of 1mH.

  2. R117 removed and shorted.

  3. R118 is removed.

  4. R119 is exchanged with 150 Ohm resistor.

All resistors are surface mount.

The result is that the sensitivity is increased in the 0.5 to 1.6 MHz range is changed from -103dBm to -112dBm at 12 dB SINAD, 70% AM.

My personal findings are that this do MW listening much more interesting and enjoyable and I have no problems with to strong signal distortion what so ever.

SM4RNA Anders

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