Adjust the P25 card settings..thats probably the reason for the warbly digital noises.
And it can be done WITHOUT a cable (I find for fleetnet the sweetspot is somewhere in the 900-1000 range)
Taken from page 56 in the manual..
Setting APCO 25 Sound Quality..
Each APCO 25 system has slightly different system settings
that control how the audio is digitized. To get the best sound
quality, you need to match as closely as possible the system’s
settings.
To adjust the sound quality:
1. While monitoring a specific APCO P-25 talkgroup, press
the HOLD/MAN key.
2. Press and hold the 9 key. On Line 1 of the screen you will
see SOUND QULTY: 0050 (for example). This shows
the Sound Quality. The lower the level the better the
Sound Quality.
3. To manually set the sound quality, rotate the scroll bar up
or down. As the threshold adjusts in increments of 100 at
the bottom of the screen watch the Sound Quality level
increase or decrease and continue to rotate the scroll bar
until you have achieved the best Sound Quality level.
Notes: • When APCO P-25 signal is not received, SOUND
QULTY: **** appears on the display.
• You must be receiving an APCO P-25 signal to
make this adjustment
A chart showing the Threshold Adjustment Range is listed
below.
4. Once you have adjusted the Sound Quality to the best
possible level, press E.
Press RSM to exit the Sound Quality Adjustment Mode.
Lower Mid Upper
Band Min Default Max Default Min Default Max
800MHz 33 533 1833 1985 2042 3342 3842
UHF 33 633 1833 1985 2042 3342 3842
VHF 330 930 2130 2147 2264 3464 4064
