alrighty then i would ask the difference tween H.O.T. & µmax systems. I know a tack hammer from a rock hammer but what's the principle characteristic's that separate them beside pin count and nomenclature. Compadre & last model Eldorado, same size box but not µmax. Same thing, how is a µmax different internally. Sorry, it's like asking coke whats in the bottle
Pinenut is right, the uMax units were in the smallest housings. It's also when Tesoro switched over to surface mount PCBs. When the Cortez was developed, it wouldn't fit in the uMax box so they made a slightly bigger box, and have used it for several other models.
H.O.T. is a higher power transmitter. I've never looked at the circuitry but most likely they boosted the supply.