"NATO standard is 24v DC... how do I get my stuff to work?"

 

 So how do you get your 12v DC stuff to work with a NATO standard 24v DC system? There are several different ways to go. The choice depends on your power budget, $$$ budget, and personal preference.

The radiobox has it's own 24v DC system. This makes for a total of four 12v batteries for a radiobox mog. All four batteries are charged by the one generator. I wanted to take advantage of this radiobox feature and thus wound up with two 12v busses, one solar and one powered by the Mog 24v suystem.
Hams are great people for using what they have "On Hand". For me that meant making use of the solar power supply I use for Field Day. This system consists of a 50w solar panel, a 12v deep cycle battery, and a charging circuit. The panel is mounted on a PVC frame and is turned manually for best solar alignment (highest power output). The panel output goes to the charging circuit which disconnects the panel from the deep cycle battery when the battery reaches full charge. This solar buss typically powers an HF rig or VHF/UHF multimode radio and TNC (Terminal Node Controller, i.e. radio modem).

My second 12v buss is run by a 24v to 12v converter. This unit is rated at 20 watts continuous duty and 24 watts surge and was less than $100 (1999). The converter buss powers the cab radios, 12v power sockets and the 222 MHz unit in the radiobox. There are terminal strips from this buss at the front and rear operating tables, as well as sockets added to the original power distribution box. With this setup the HF and VHF/UHF rigs can be run at times the solar panel is not convenient.

"Can I just tap 12v from one of the batteries" Well, yes and no... kinda depends on who you talk to. "Yes", if your current drain is small; "No", if it is large or you are a "purist". Let's`look at the two.

"Yes", it is possible to do this, but the caveat is the "tapped" battery will discharge faster than the "untapped" one. Your batteries won't charge evenly and eventually battery replacement becomes necessary. If you have a heavy current draw this will become apparent right away, and your answer would be "No". If your draw is small, it may take awhile to become apparent, or you may never really notice this. My experiance with a two-battery setup is that the batteries will not discharge or charge at the same rate resulting in one with a shortened life.

"What about 120v?" For now all I have done in this area is mount some receptacles under the front table and use a generator to supply 120vac. There are reasonably priced 24vdc to 120vac inverters available, but that is for the future.

Send comments and mail to
Ed Wright, kb6tho@mraradio.org
Copyright 2001 The Mountain Repeater Association
Last updated by Ed, KB6THO on 1/15/01