ya need to check out what they have in mods for the 148gtl 5 pins same board , same mod s for modulation , ya can change a couple of diodes to up the modulation .
MODULATION: Remove R104 or TR32
AM POWER: VR6
SSB POWER: VR7
"RX" METER: VR1
"TX" METER: VR10
SQUELCH: VR2
TX FREQ.: VR3
CARRIER BAL: VR5
DRIVER BIAS: VR8
FINAL BIAS: VR9
MOD. METER: VR12
POWER TWEAK
1. Remove TR32
2. Replace R99 (10k) with a 2.2k
3. Replace R94 (10k( with a 2.2k
4. Re-tune coils L36,L37 for maximum forward AM power.
CLARIFIER:
1. Remove R187
2. Remove D36
3. Jumper D35
4. Follow the RED WIRE from the clarifier control to the PC board and UNSOLDER it.
5. RESOLDER this RED WIRE to pin 3 of regulator IC MB3756.
6. Follow the ORANGE WIRE from the clarifier control to the PC board and UNSOLDER it.
7. RESOLDER this ORANGE WIRE to the PC board ground.
NOTE: The Orange and Red wires may need to be reversed in some radios for this to work right.
8. Re-align center slot by adjusting CT3.
If all went well and you didn't smoke your radio, you should slide about 1 Kc up and 4 Kc down.
CHANNEL TWEAKS:
EASY TWEAK: Install EXPO 100 kit "B".
FOR THE DRILL HOLES ALL OVER MY RADIO LOVERS...:
1. Replace 11.1125 crystal with a 11.3258 crystal.
2. Isolate the ground pin 10 of the MB8719 PLL by cutting the PC trace.
3. At this point, turn your radio on and check to varify that all channels are locked in and working. If it is not, adjust these in the following order:
a. CT3 for USB.
b. L20 for LSB.
c. L19 for AM.
4. Install a SPST switch between pins 11 and 12 of the MB8719 PLL
5. Install a SPST switch across the cut you made to isolate pin 10.
6. Check all connections for shorts.
7. Check to make sure everything is working before you drill holes for the switches!
ROAD MAP:
SW1 / SW2 DOWN: NORMAL 1-40
SW1 UP / SW2 DOWN: (ch.15-27) 26.815 to 26.955
SW1 UP / SW2 UP:
1= 27.605 6= 27.505 11= 27.565 20= 27.525
2= 27.455 7= 27.515 12= 27.585 23= 27.575
3= 27.465 8= 27.535 13= 27.595
4= 27.485 9= 27.545 14= 27.605
5= 27.495 10= 27.555 16= 27.475
SW1 DOWN / SW2 UP: (ch. 1-40) 27.605 to 28.045
. Can anyone tell what the range of this pot is supposed to be? And why moving it made no change in modulation level? The radio is pretty much at 75-80% all the time, AM or SSB it seems.