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1997-02-01
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From netcomsv!micromed!brett Tue Aug 10 09:26:43 PDT 1993
Article: 25706 of rec.radio.shortwave
Path: netcom.com!netcomsv!micromed!brett
From: brett@micromed.com (brett miller)
Newsgroups: rec.radio.shortwave
Subject: ATS803A Anti-Chuff Mod
Message-ID: <37k38B2w165w@micromed.com>
Date: Tue, 10 Aug 93 07:09:49 PDT
Organization: Micro-Medic BBS - +1 408 279 5240 - Public Access
Here is the mod for the DX440 and Sangean ATS-803A that allows you
to hear the receiver as you spin the dial instead of getting muted.
I don't know who the original poster was, but I don't take credit
(or blame) for this mod, but it does work.
---------------------------------------------------------------
Sangean 803 / DX440 Modification
The following mod will remove the "chuffing" heard while tuning the
Sangean 803/DX440 radios.
WARNING: a. This operation will void your warrantee.
b. You do this at your own risk.
1. Place the radio face down on a suitable surface and orientate it so
that the base of the radio is towards you.
2. Remove the battery cover and take out the D-cells. You do not need to
remove the AA batteries but you will lose your clock and memories, so
make a note of them before you go on.
3. Remove the six screws which hold the back of the radio in place. One
of these is in the battery compartment.
4. Lift off the back cover and swing it over towards your left to lay it
down. This is to avoid breaking off the wire going to the whip
antenna.
5. Locate the 8-wire flat cable which runs from the circuit board above
the loudspeaker on your right horizontally across to the rf/if board.
The cable plugs into an 8-pin socket which is located almost dead
center in the radio on the rf/if board.
6. Carefully remove the cable from its socket. Identify the second wire
from your left in the cable. (Second to last on the side furtherest
from the loudspeaker.) Bend this wire up and out of the way (or cut
it off!) so that it will not plug back into the socket or make contact
with the socket in any way.
7. Carefully plug the cable back into the socket and check that the wire
you modified is not making contact with the socket.
8. Repeat steps 4 through 1 in reverse order and reprogram your clock and
memories.
9. Turn on the radio and enjoy the lack of "chuffing". (You may still
hear a "thud" while tuning across a strong station.)
Remember: a. This will void your warrantee but if done carefully it is
reversible.
b. Follow the above instructions at your own risk.
The main purpose of the muting circuit that gets disconnected by this
modification is probably to make the set silent when you hit the
"search" button. I personally think that it is a feature to hear the
"search" in operation.
The reason why the set is "chuffing" is a result of a bad desing of the
mute circuit:
It is placed where there is a DC potential.
It is placed after the volume control (less audiable if placed
before).
------------------------------------------------------------------
Brett Miller N7OLQ @ N6LDL.#NOCAL.CA.USA
brett@micromed.com
--
brett@micromed.com (brett miller)