Ray,

Don't have a PP-4514, and am not going to ham fests but, I do have, if interested, a RACAL MA-949 unit.  Looking at manual

appears can be modified to supply 12V at 5+ A, has a built-in audio amp with speaker for pack sets.  Manual available at

<electrotanya.com>.  Measures 88mm X 395mm X 215mm, weighs 5.5 Kg. 

Rod K0EQH