Sangean ATS 818 Mods wanted
Leigh M. Preece
Sangean 818 Mods wanted - must be for this particular model as earlier
mods for earlier sets do not apply to this model.
I want the 'anti-chuffing' mod that occurs when tuning up and down -
muting the audio while it does so, which can be useless when varying
SSB signals.
All help appreciated.
Leigh....
--
***** Leigh Preece *** le...@media.keele.ac.uk ****
**** Media and Communications Centre, Keele Uni ***
***** leigh hat media dot keele dot ac dot uk *****
** remove 'spamfree' from address when replying ***
Erick Jasiunas
Leigh M. Preece wrote:
>
> Sangean 818 Mods wanted - must be for this particular model as earlier
> mods for earlier sets do not apply to this model.
>
> I want the 'anti-chuffing' mod that occurs when tuning up and down -
> muting the audio while it does so, which can be useless when varying
> SSB signals.
>
> All help appreciated.
>
> Leigh....
> --
Leigh,
I performed this mod on my ATS-818, and it works really well. It only
involves removing a single capacitor and replacing with a jumper - easy
to undo. Tandy DX390 is same model as Sangean ATS-818.
I found it listed as 2 parts - dx390-1.mod and dx390-2.mod
Located at:
http://ftp.barc.org:8080/pub/hamradio/mods/tandy/
Start:
dx390-1.mod
*
* Scott,
*
* I did a mod on my DX-390. It will disable the squelch used to
* keep the user from hearing the phase lock circuit as he/she
* changes. It also keeps a person from being able to "scan the
* band" and hear all he/she scans. Anyway, remove the cover and
* circuit board. If the user doesn't have the external power
* supply, they will need to remove the unit's batteries an hour
* before they do the mod. If they don't, they will believe they
* have zapped the radio. The radio's memory needs to be fully
* discharged. After they have done this, remove C167. It's a
* 1 microfarad capacitor near the volumn control. My mod's been
* in effect for two months without any "odd" influences to the
* radio. CUL. Phil Heaton.
*
*
dx390-2.mod
*
* Scott,
*
* One important thing I forgot to mention about the mod to
* the DX-390, place a jumper wire in place of C167. Sorry
* about that, rough quarter. Phil Heaton.
*
End:
Hope this helps,
Erick.
Rick W 999
>Sangean 818 Mods wanted -
Try this:
Subject: anti-chuffing mod for DX-380/ATS-808
Rules:
you may copy this posting, and give it away for free. You may
NOT sell
copies of it. You may NOT include this posting in any
publication for
which any price is charged. You may NOT store this
message on a computer
bulletin board that charges users any fees. This
message may be given away
freely, but NOT sold.
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.)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.
This
message may be given away freely, but NOT sold.
This message is Copyright
(C) 1992 by Kenneth J. Hendrickson
Hope it works!
...Rick...@aol.com
DOMofCAL
I have the Sangean ATS 803A and am wondering if the instructions for the 818
model for disabling the muted audio will also work on this model, or if anyone
can provide me with an instruction that will work.
Thanks...Dominic
Rick W 999
No, but here are the ones for the 803A:
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).