Here is a good set of power/audio mods for the Cobra 148GTL. I couldn't find these in the search, so I reposted it.
Also applies to:
Undien Grant XL
Uniden Grant LT
1. Carrier Adjustment: VR10. If lower carrier is desired, change R196 near VR-10. Try about 270 ohms.
2. Change R114 to a 10K, and C46 to a .2 monolithic, this will widen up the audio on AM
3. The AMC is TR-26. You can remove it, and still have good results on AM
, the ALC for SSB
is not effected by this. If you don't want the AMC disabled, leave it. the other way to disable the AMC is cut R131. Check both to restore AMC from previous mods.
4. If extra frequencies have been added, perform the following to widen up the band pass filters to recover lost power at the highest and lowest frequencies: C163 - 4pf, C41 - 3pf
5. R180 - Jumper it. This brings up the gain of the TX
6. IC TDA6130 - Pin 12 to ground through 100 ohm resistor. Upper left, pin 14 = ground.
7. Remove the AM
regulator, (usually a 2SC1419) and replace it with a 2N6487.
8. C174 - remove, add 1000uf electrolytic. connect POS to base of yellow wire next to it. If the yellow wire is too far away, it might be easier to connect the POS leg to the leg of the AM
regulator closes to the back of the chassis via the bottom of the radio.
9. For 148F, change C18 to a 1000uf electrolytic, 16V