How many amps ?

[W5LZ]

Think of it like this. Figure 300 watts divided by 12 volts which will give 25 amps. But you also have to remember that any electronic device is never 100% efficient. On an average it may be 50% efficient. That means instead of 25 amps it will mean 50 amps. Now keep in mind that the advertised current rating for most power supplies isn't the constant current it can supply, but the intermittent current. The intermittent current supply (ICS) is usually something like 120% of the constant current supply (CCS) rating at best, or that you would need about 20% more than that 50 amps to run that amplifier. You end up around 60 amps of constant current supply required.
You may not like it, but that's how it is. Trying to estimate the input current from the output power of an amplifier is never just a straight division problem, you have to figure efficiency into it like I did above. That isn't going to be a 'dead-nutz' 'sure thing', it's only an estimate, and a low one at that.
Have fun.
- 'Doc

 

[jvergot]

How many AMPS for 2970

This is jvergot, AKA headjammer, i think a 30 amp ps will do fine but you can go online to the ranger radio website and they will break down ps requirements for their mobile radios.

 

[Lowflyer]

Never run an amp at full power if you want it to last. Stay at 80% or less.