I love 148 GTL radios and have messed with them alot. Tried the ekl finals, the dual 1969 mod. I have gone to just a good peak & tune after the radio is at operating temp, especially when doing an alignment. The tend to be off when cold and if you align them cold, they will drift high... Some say replacing L26/L27 will correct it, but they all seem to drift...
It is one of the most stable ssb radios out there, and am beats most radios (non DX) out there.They may be in the 12~15 watt range, but they sound a ton better than any over modulated, clipped, ekl'd 29 out there pushing 30 watts.
I dont care for the new model, (side mounted mic plug) they have terrible ssb (unstable due to the change in power distribution) and they tend to have resistor problems alot as well.
Do a good alignment, then peak and tune, don't clip the audio and you'll have a great radio! If you need to add power to reach your buddy, hook up a nice footwarmer and talk all night!