19 lines
1.1 KiB
Plaintext
19 lines
1.1 KiB
Plaintext
|
PCS4000.2
|
|||
|
|
PCS-4000 MOTORBOATING MODIFICATION
|
|||
|
|
==========================================================================
|
|||
|
|
This modification cures a problem which appears only in some radios,
|
|||
|
|
particularly when the radio is very cold. It is variously described as,
|
|||
|
|
"You sound like you're underwater" or, "You break up on loud peaks," or
|
|||
|
|
garbled transmit audio.
|
|||
|
|
It is sometimes caused by RF getting into the radio. This is easily
|
|||
|
|
cured by connecting a .001 ufd. ceramic capacitor between pins 2 and 5 of IC402.
|
|||
|
|
|
|||
|
|
In extreme cases, lowering the audio gain of IC402 by changing r472 to
|
|||
|
|
a lower value may be of benefit. In older models, this original resistor
|
|||
|
|
is 100 k-ohms; in newer radios it is 51 k-ohms. Try lowering it to 47k or 39k.
|
|||
|
|
To get at the bottom of this PC board, remove radio top cover (4 screws;
|
|||
|
|
note that right front screw must be a short screw), unsolder a red wire from
|
|||
|
|
a post on the front left of the board, unplug the coax from J404 and the 6
|
|||
|
|
wire plug from J401. Remove 7 screws and flip board over to the right.
|
|||
|
|
Reverse this procedure to re-assemble.
|
|||
|
|
|