Another way is to look on map 3 for a Hydrite Soldier with a trikorder.
Exactly. Why bother with level 5 at all, until your level is high enough that you don't get full XP anywhere else? Go to the prison to get the TriKorder, thus:
* in the course of wandering the wastelands, you will find hydrites on every level. Kill them. If their radiation is less than 50%, they will drop keys. Get 1 each of red, blue and green keys. If you are lucky and find Aurora, you can find out which key you need for each cell in the Hydrite prison, but otherwise, just take all 3.
* go to level 4 with a tevix-bahn, z-tempest, shezvarin as described.
* beat up a few monsters until you have a telegrasp (they're pretty common). If you get a xendrix, reflecto/polycarb armor, or a hydra-jack in the process, bravo! But you want the telegrasp.
* return to level 3 and the hydrite prison. By now there's probably piles of duroplast lying around everywhere, so pick one up on your way to the prison.
* Fight and kill the three rad-hounds guarding the prison doors. You must kill them, not just defeat them.
* Use the duroplast on the prison doors, and go in. If the duroplast is a dud, you will need to leave, come back with more duroplast, and try again until it works.
* Enter the prison and wander around, killing Hydrites. Perhaps a third of the hydrites on level 3 have a TriKorder, and so your chances of getting one are pretty good, given the number of times you will be jumped by guards as you wander the prison.
Two other things to do in the prison:
1) Free any captured recruits for a big XP bonus (give them a telegrasp if you have one to spare)
2) Find Cell I, open it, and get a code key. This is needed to enter the Air Force Bases, and finding it in the prison is a better use of your resources than bribing Barl for one.