for what reason? your output requires 5v at .5A. something that can output 3x the amperage is more efficient. the chip will use what it needs and no more. a wider input is always good. i can look up the exact VR i used sometime around the 6 or 7th when i get back to where my radio is.
the recom VR that is suggested is not very efficient, much better then stock but still not ideal. it also takes up more physical space.
same series may be not too good but it is easy.
I think you need todo some research before making such wild accusations.
The recom VR (also the one i sell) is 90% efficient...and i dare you to find something more efficient that is a direct replacement and less than what a recom costs. I'm not saying 90% is as high as it gets, but without additional circuitry or a really high price tag, its really hard. I searched for quite sometime before settling with the recom. It's price is abit high, but you'll save the costs after one set of batteries.
With the stock VR, the radio pulls ~130ma with the backlight on and ~110ma with the backlight off.
Toss a recom in there, and it pulls ~75ma with the backlight on and ~60ma when the backlight off.
So it will nearly double the battery life
.5A is more than ample for the gt3b, adding more to its power handling capabilities doesn't necessarily make it more efficient... According from what you've described, you simply replaced a 7805 regulator with a 7805 regulator that can handle more current. And no mater what, a 7805 is a linear regulator so to get the low voltage, it turns some of the high voltage into heat. Which means not very efficent. If you do the math, at 12 volts, a 7805 runs about 40% efficiency in a setup like this
So, to make math easy lets say the GT3B needs 5 volts and 50ma of power. Figure that out in watts. 5 x .05 =.25 watts
Now figure out the power lost in the conversion
12 volts - 5 volts = 7 volts
7 volts x .05 amps = .35 watts
Now add those two figures together to get total power
.35 + .25 = .6 watts
So to find effiency, .25 watts divided by .6 watts = .416 or 41.6%
This is true for any 7805 regulator, possibly worse depending on the quality of the VR
You could argue that you found a switching regulator in a TO-220 package, but that would mean it requires additional circuitry or it costs more than the recom. I have yet to see a TO-220 switching regulator that costs less than the recom.
A switching regulator, can theoretically, have 100% efficiency, It simply rapidly switches the voltage so less voltage comes out. It needs other circuitry though to make it a nice smooth output. Most, require this to be external. However, the recom packs it all into one nice package to be a direct TO-220 (7805) replacement.
Also, you mentioned that the recom is bigger and takes up more space, which i have to disagree with again. The recom has a smaller foot print than a TO-220 package. Its thicker than the TO-220 package, and may have slightly more volume than a TO-220 package. But its alot more compact, and i'm pretty sure anyone who has to design a circuit board would much rather the recom package on there than a TO-220, unless they needed the board to be thin, but in that case, go SMD. OR, if you want to factor in the heat sink that the TO-220 should have on it, then the recom is ALOT smaller than that the TO-220 package.
Feel like arguing some more? We can get very technical if need be. I am very confident, that there is not a TO-220 package regulator that is MORE efficient than the recom and CHEAPER than the recom.
There may be another switcher thats more efficient than the recom, and slightly cheaper, but i doubt it (especially if its a drop in replacement for a 7805)
Back on topic....its a great radio for a first timer, don't let all this silly talk about vr's worry you. I promise you the VR i sell is a excellent option and its what 98% of the people who preform the mod choose
to a hacked GT3B/C.