When the SM-230 is used as a bandscope, the attenuator circuit is bypassed. Sometimes it is necessary to use the attenuator during strong signal reception or high noise conditions. The following modification will allow the attenuator circuit to function in the bandscope mode.

Required parts:
W05-0309-00 ATT SUB-UNIT

1. Disconnect the power cord patch cords.
   
   
2. Remove the top cover (6 screws).
   
   
3. Remove the Horizontal unit's mounting screw and secure the ATT sub-unit with the supplied 2.6mm screw washer.
   
   
4. Remove connector P12 from the Horizontal unit and insert it into jack P1 on the ATT sub-unit.
   
   
5. Insert connector JA from the ATT sub-unit into jack P12 on the Horizontal unit.
   
   
6. Insert the two wire plug, supplied in the kit, into jack P2 on the ATT sub-unit.
   
   
7. Solder the exposed ends of the red and the brown wires to the Panel units as shown in figure 2.
   
   
8. Solder the two jumper wires (they look like resistors) as shown in figure 2.

This modification may be covered under warranty.
Time required to perform the modification is ½ hour or less.



21-04-2000 SM-230 RTTY cross pattern attenuation
Author: Kenwood Communication, inc.

Some users of the SM-230 have reported that the MARK and SPACE gain adjustment do not sufficiently reduce the signals to display them on the CRT. The following modification will correct this condition.

Required parts:
680 ohm 1/8 watt resistor. RD14CB2B681J QTY. 2

1. Disconnect the power cord and controls cables.
   
   
2. Remove the top cover (6 screws).
   
   
3. Locate the Horizontal unit. This board is vertically mounted on the right side of the SM-230.
   
   
4. Locate resistors R318 and R322 on the Horizontal unit.
   
   
5. Replace R318 and R322 with 680 ohm resistors.
   
   
6. Assemble the SM-230.
   
   
7. Adjust the MARK and SPACE gain adjustments as necessary to obtain the correct cross pattern.

Time required to perform this modification is 1 hour or less.