
2
__7. Locate the IF cable plugged into J2003 on the left center part of the IF
board and pull it out.
__8. Feed the IF cable under the wires between the IF and Audio boards, and
insert it into the coax jack marked IN on the mod board.
NOTE: Be sure the orientation of the mod is correct. It should plug into the
group of 5 pads, not the group of 6. In some radios this cable may seem to be
too short to reach to the Inrad mod connector. Sometimes a gentle tug is all that
is needed to extend the cable far enough. If that doesn’t work, it will be
necessary to remove the top of the radio. Look below the fan near the RF board
below at the cable bundle that contains the coax cable we are interested in. It
may be necessary to remove the fan to get at it. There is a cable tie which is
holding the cable too tightly and it must be cut. This should free up enough cable
to reach the Inrad board.
__9. Insert one end of the cable supplied with the kit into the coax jack marked
OUT on the mod board.
__10. Insert the other end of the supplied cable into J2003 on the IF board.
NOTE: While the radio is still open, you may wish to install the BONUS mod. If
you operate CW and like to use the analog detector, this mod will greatly improve
the sound of your radio. It does nothing for the other modes or for CW operation
with the DSP detector. See below for installation instructions.
__11. Replace the cover and set the radio right side up. Replace the line cord.
__12. Hold down FAST and LOCK and turn power on. Press FAST and ENTER
and select menu item 9-1.
__13. Decrease the setting by 2 integers. Note that this setting is not critical
BONUS: MAIN RECEIVER AF FILTER MODIFICATION (Thanks, K9AN)
Both the main and the sub receivers have an active low pass filter in the audio
chain. These filters are in use when the DSP is off. (Many CW operators prefer
to listen with the DSP off.) The pass band of the main receiver is flat with a –3
dB point about 1400 Hz. The sub receiver peaks up about 4 dB at 600 Hz and
has a –3 dB point about 900 Hz. The sub receiver has a substantially lower
response to the noise components above 1000Hz, which makes it more pleasing
to listen to. The addition of one capacitor to the main receiver low pass filter can
provide a similar audio response and cut the high frequency hiss by 10 dB. This
makes a substantial improvement in the sound of CW.
To install the bonus capacitor mod, locate C3015 on the audio board central part,
nearer the rear panel. Fashion small hooks on the bonus capacitor leads very
close to its body. Bend C3015 over gently and hook the bonus capacitor leads
over C3015 leads. Solder quickly with a small iron. Use care to not unsolder
C3015.