Subject: anti-chuffing mod for DX-380/ATS-808
From: [email-masked] (Kenneth J. Hendrickson)
Newsgroups: rec.radio.shortwave

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This message is Copyright (C) 1992 by Kenneth J. Hendrickson.

I bought a Service Manual from Sangean to do this mod.  You may or may
not have to buy one to figure out which parts to remove.  The Service
Manual was very cheap, being only a xerox copy of the real thing.  It
was very difficult to tell the difference between circuit board tracings
and components, because it wasn't printed in two colours as standard
service manuals are.  Sangean receives an F.  I may never buy another
Sangean radio because of this poor manual.  I can't berate this service
manual enough.  It wasn't worth the $12 I paid for it.  Xerox costs
would only have been $4 at the relatively expensive cost of $.10/page.

anti-Chuffing mod:	remove chip resistors R109 and R110 on the back
	side of the main board.  (You could also remove Q27 & Q28, but
	the resistors were far easier to get at.)

        ascii artwork:            ^
                                  |
         O   O****O		speaker
        **  *
        **R110****O
        **  *        		audio amplifier section
       ***R109**
       **  *   *
       *  O    O
       O   *
            ***O

	The *'s are copper traces.  The O's are connections to the other
	side of the board.

	The section of the circuitry shown is on the back side of the
	main board, at the bottom, and at the left side of the speaker,
	about 2/3 of the way from the left side of the radio, as the
	speaker faces downward.  It is not necessary to remove the
	control board to perform this mod.

After performing the mod, it became obvious why Sangean used up circuit
board space, two transistors, and several biasing and bypassing
components, building this "feature" into the radio.  When switching
between bands, and when turning the radio on and off, there is a short
sharp squeal as the VCO settles to the right frequency.  It is annoying,
but it is offset by being able to tune up and down the SW bands as
slowly or quickly as desired, while listening to what is going on.  I
really like the radio after the modification.

Suggestion to Sangean (just in case you're reading this): since the
radio is computer controlled, software should be written for the
controller that uses the audio muting circuitry during power-up,
power-down, band changing, and frequency changing by direct frequency
entry or memory selection.  The muting should *not* be used while tuning
with the tuning knob, tuning buttons, or while scanning.  (It's really
pleasant to be able to hear what's happening during scanning as well as
manual tuning.)  Since you really do need the audio muting feature
(since the average person would never put up with that VCO settling
squeal), and since it is already in the radio, and since it would cost
basically nothing to include extra software to mute during all tuning
*except* manual tuning and scanning, let's see this in the next model.
========================================================================
Note: I haven't tried or verified this, proceed at your own risk. WA2ISE
/EX