At 12:07 PM 03/25/08, you wrote: >At 09:56 3/25/2008, Steve S. Bosshard (NU5D) wrote: > >Anyhow, without a fuse, the reverse protection diode or transorb in the > >radio tries to short and shunt the reverse current from the radio. > >So you are saying it is in parallel (and reverse direction), not >series (in forward direction)?????
Parallel wired reverse protection diodes are standard design procedure. Have been for years. They gut away from series diodes in the 1980s... and for a good reason. I saw this years ago on a Midland 220 mobile that was rated at 10w. At 13.8-14v (the average automobile the output was 12-13w or so. with a voltage drop of only 7 tenths of a volt (the average drop across a series diode) the output power was 8 to 9 w. Modern radios with power bricks don't show that as much, but you get the idea. But a series diode still isn't going to save you in the dual battery situation with the starter motor sucking 300 (or so) amps and putting inductive spikes back on the line. Mike
