600 ohms will be a challenge for you, you wont likely have it, however several simple solutions exist and one if it works is free sans your labor effort. With out making the time to look this up, id bet pretty good money the actual speaker coil is 3.2-16 ohms range and I'd not be too afraid to bet more in the 3.2-4 ohm range. but you have to first get to the actual coil. 600 ohm is typical and esp for Mil equipment, open it up, the various pins and such were/will be for powering the preamp inside your unit all the while knocking down the 600 to the much lower ohm range I previously mentioned, find the actual speaker, 2 wires will be affixed likely those will be spade lugs or at the worst soldered onto the actual coil tabs, if soldered, then trace these 2 wires back to the electronic modual and see if in that scheme they don't terminate onto a terminal strip of some sorts, take your time this i am presuming is pretty new turf for you to be exploring. but worst case you might have to lift the wires away from the coil tabs or absolute worst cut them, if you cut them cut emm very close so you should at the end of this drill have enuff wire to re-terminate them if it ultimately suits your needs, once the coil tabs are free measure across with your vom meter of some sorts you have, reading ohms, this is where you will see the 3.2-16 number pop up on ur meter scale. don't do anything dumb and play with any type of battery across these terminals. if and I presume you will find an ohm reading as I made mention then how or what you feed into the speaker is your decision. I will be very surprised if this speaker is not a 2-5 watt speaker, maybe more until I see it and confirm, sometimes the actual speaker is identified with the impedance and wattage being marked onto the speaker somewhere. at this point remember you will not be using any part of the preamp or the mil spec plug.. till you either make some determinations or I search out your speaker this is about as far as we can go till I now more and also your technical comfort level..
I omitted, if you just have to have or want 600 ohm input, then you will need to buy a transformer, most typically 3.2-600 or reverse it and use 600-3.2 , this all becomes a circus and I would skip this aspect of it..
good luck mac/mc
