Modifications for the Kenwood
TR-7930
19-07-1998 TR-7930
info
Insert the spread terminal "8-m" into the top of plug "j-18"
so it fits around the top of terminal "ap".This is a fairly tight fit, so use
care not to bend the terminals by using too much pressure.
About half of
terminal "8-m" will stick up above the top of terminal "ap". The lower part will
be firmly sleeved around terminal "ap" inside the plug.
Dress the wire around
the left side of the board.
Replace speaker plug and install top
cover.
Plug tnc cable with ptt/audio in/audio out/ground connectons into
mic connector and it's ready to go on packet/rtty.
No soldering is required
and unit can be returned to original state at any time if
necessary.
19-07-1998
TR-7930/7950 transceiver for packet/rtty operation
Circuit modification for Kenwood TR7930/7950 transceiver
for
packet/rtty operation
by: WA4IXN
This modification provides
controlable audio output to pin 5 of the mic connector for single plug packet/
rtty operation.
Remove top cover of transceiver and carefully disconnect
speaker lead plug from "rx unit" board.
Locate plugs"j-13" on the right front
of the "rx unit" board and "j-18" on the left rear side of the board.
Notice
which wire goes to pin "8-m" on "j-13" and to pin #5 on the mic
connector.
Remove plug "j-13" from the board and locate the spring tab on the
side of the plug that holds the "8-m" connector in place.
Using a small awl
or pointed tool, press the tab down and carefully pull the "8-m" connector from
the plug.
Work the wire from the harness so it will reach back along the left
side of the board to plug "j-18".
Using the awl or small pointed tool,
carefully spread the "8-m" connector a slight amount so it can be fitted Like a
sleeve over another connector of the same size.
locate terminal "ap" on plug
"j-18".
Insert the spread terminal "8-m" into the top of plug "j-18" so
it fits around the top of terminal "ap". This is a fairly tight fit, so use care
not to bend the terminals by using too much pressure.
About half of terminal
"8-m" will stick up above the top of terminal "ap". The lower part will be
firmly sleeved around terminal "ap" inside the plug.
Dress the wire around
the left side of the board.
Replace speaker plug and install top
cover.
plug tnc cable with ptt/audio in/audio out/ground connectons into mic
connector and it's ready to go on packet/rtty.
No soldering is required and
unit can be returned to original state at any time if necessary.
19-07-1998 TR-7950/30
RX Interference
4-8-83
Some users have reported FM Broadcast or TV
video carrier interference to the receiver. Normally the TR-7950/30 has
excellent two signal intermodulation characteristics. For a reported case of
Broadcast or TV IMD the following modification may reduce or eliminate the
interference.
Parts Required
Qty Description
1 MI-308
Diode
Procedure
- REmove the top and bottom covers.
- Remove the 4 screws that secure the heat sink assembly to the rear of the
set. Gently pull the heat sink assembly to the rear, to allow access to the
final unit X54-1270-1-,11.
- Remove the 5 screws securing the PC board to the heat sink. Remove the 2
screws securing the final module (M57733/M57726) and remove the screw that
secures Q2 to the heat sink. Carefully desolder L9 from the antenna connector.
(Dont change the spacing of the coils!!!)
- Gently fold the assembly over to allow access to the foils side of the
final assembly and remove D2, and replace it with the MI-308 diode.
- Reverse steps 1-3 to reassemble. Reconnect L9 but don't change the spacing
of the coils. Use heat sink compound when replacing the final module.
This is an optional change and may not be performed in
warranty.
09-04-2000 TR-7850/30
RX interference
Author:
Trio-Kenwood Communication, inc.
Service Bulletin no. 870 (8-4-1983)
Some users have reported FM broadcast or TV video carrier interference to the
receiver. Normally the TR-7850/30 has excellent two signal intermodulation
characteristics. For a reported case of broadcast or TV IMD the following
modification may reduce or eliminate the interference.
Parts required
Qty Description
1 M1-308 Diode
Procedure
- Remove the top and bottom covers.
- Remove the 4 screws that secure the heat sink assembly to the rear of the
set. Gently pull the heat sink assembly to the rear, to allow access to the
final unit (X54-1270-10,11).
- Remove the 5 screws securing the PC board to the heat sink. Remove the 2
screws securing the final module (M5733/M57726) and remove the screw that
secures Q2 to the heat sink. Carefully desolder L9 from the antenna connector.
- Gently fold the assembly over to allow access to the foil side of the
final assembly and remove D2, (figure 1), and replace it with the MT-308.
- Reverse step 1 - 3 to reassemble. See figure 2 for proper connection of
L9. Use heat sink compound when replacing the final module.
Note: This is an optional change and may not be performed in-warranty.