Alternative to the PDP and VRM

[The Lucas]

I assume you are also using the old radio and you need (or already have) a source of 5V and ~2A.

If you ask around teams in your area, someone will probably loan/give you a 12V to 5V converter that used to be required for the radio, due original radio being 12V. It looks like this one (common style):
http://www.amazon.com/RioRand-Waterp...dp/B00JM07LMY/
AndyMark and others sell this one:
http://www.andymark.com/product-p/am-3068.htm
ServoCity has this Step up/Step down one:
https://www.servocity.com/html/5v_st...l#.VtE1M5wrI1I
I haven't used either of the last 2 products, but I probably am going to buy the last one (if I can't find a similar higher amp one) to power some cameras rather than a 2nd VRM. Of course, you could always make your own circuit with parts you might already have.