Subject: Improving Audio in the PRO-2005/6 Scanners
Tom Wheeler, N0GSG
Johnson County Radio Amateurs Club


The Realistic PRO-2005/6 scanners are considered by listeners to be
one of the finest scanning receivers available. These units cover
25-1300 MHz in AM, narrow-FM, and wide-FM modes with only a single
break in coverage from 520-760 MHz. All this was packaged for under $400,
(and under $300 when they were finally discontinued by Radio Shack.)
There is one major fault with these receivers: The audio fidelity
is very poor. The designers did a great job in the RF sections of
the receiver, but must have slept through the audio design!


Scanners are not supposed to be hi-fi receivers; however, their audio
performance should be at least as good as a common amateur transceiver.
The author compared the audio of the PRO-2006 with that of the Kenwood
TM-2550 transceiver. Even when the '2006 was connected to a good-
quality external speaker, the audio was miserable. The culprit: Several
coupling and bypass capacitors in the audio section have been mis-
calculated by the designers.


Making the component changes suggested below will dramatically increase
the audio quality of the PRO-2005 and 2006 scanners. These two units
are virtually identical (The main difference is that the LCD backlight
can not be dimmed on the '2006. It can only be be turned ON or OFF.)
Be aware that alterations to your scanner might void any warranty left,
and if not carefully done, can be hazardous to its health. Any work
on these units should be done at a static-free workstation, if possible.
THE AUTHOR ASSUMES NO LIABILITY FOR THE INFORMATION CONTAINED HEREIN!